Sex-biased dispersal in Tetranychus urticae mediated by population density but independent of sex ratio

Sex-biased dispersal in Tetranychus urticae mediated by population density but independent of sex ratio | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Sex-biased dispersal in Tetranychus urticae mediated by population density but independent of sex ratio Peng Zhou, Yujie Zhang, Xiong Zhao He, Zhihan Wang, Yalin Fan, and 3 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-7472280/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract Dispersal is a multiple-stage process which can be affected by intrinsic phenotypes and extrinsic environmental conditions. Understanding how animals adjust dispersal strategies in response to these factors is essential for predicting population dynamics and providing knowledge for population management. Tetranychus urticae Koch (Acari: Tetranychidae) is a notorious invasive pest of global concern, damaging numerous economically important crops. Here, we examined the effect of sex, population density, and sex ratio on dispersal probability and distance in T. urticae . We set up a factorial design with three densities and three sex ratios generating nine treatments. Our results show that dispersal was generally female-biased, and dispersal probability and distance increased with population density in both sexes, but the increase was significantly stronger in females. In contrast, sex ratio and interaction between sex and sex ratio had no significant effects on dispersal probability and distance. Females that dispersed farther laid eggs over longer distances. Females at female-biased sex ratios and dense populations produced more eggs but resulted in lower offspring survival rates, indicating severe intrasexual competition. We suggest that sexual dimorphism in body size, along with the relatively high benefits and low costs of female dispersal compared to males, may lead to female-biased dispersal in spider mites. Multiple mechanisms including female intrasexual competition and male harassment to females may account for the observed dispersal patterns in relation to population density and sex ratio. Female intrasexual competition and male harassment may drive female dispersal, resulting in wider egg distribution across habitats and potentially facilitating pest population outbreaks and range expansion. dispersal distance dispersal probability intrasexual competition sex-specific dispersal sexual conflict Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Introduction Dispersal is often described as a three-stage process involving emigration, inter-patch movement, and immigration, each of which is influenced by both intrinsic phenotypes and extrinsic environmental conditions (Clobert et al. 2009 ; Bonte et al. 2012 ; Matthysen 2012 ; Baines et al. 2019 ). Therefore, an individual’s dispersal decision and ability are influenced by intrinsic factors such as sex and body condition, and extrinsic environmental conditions including population density, sex ratio, and resource availability (Matthysen 2012 ; Laska et al. 2023 ). Among the factors influencing dispersal, their effects on emigration may differ in magnitude or direction compared to those affecting subsequent movement and immigration (Chaput-Bardy et al. 2010 ; Matthysen 2012 ; Dahirel et al. 2016 ; Hewison et al. 2021 ). To date, previous studies on factors affecting dispersal process mostly focused on emigration (e.g., De Meester and Bonte 2010 ; Baines et al. 2017 ; Mishra et al. 2020 ), how different environmental factors may affect dispersal, such as distance, oviposition, and egg/offspring distribution is largely unexplored. A better understanding of how phenotypic and ecological factors affect the dispersal processes is critical for predicting pest population dynamics (Matthysen 2012 ; Renault 2020 ; Santini et al. 2025 ) and developing pest management strategies. Sex is among the most important phenotypic drivers influencing dispersal, with sex-specific patterns reported across diverse taxonomic groups (Johnstone et al. 2012 ; Trochet et al. 2016 ; Li and Kokko 2019 ; Franckowiak et al. 2025 ; Zsinka et al. 2025 ). Several evolutionary mechanisms have been involved in explaining sex-biased dispersal, such as inbreeding avoidance, kin competition, parental care, sexual dimorphism, asymmetries in dispersal costs or benefits, and intra- and intersexual competition (Perrin and Mazalov 2000 ; Gros et al. 2008 , 2009 ; Bonte et al. 2012 ; Li and Kokko 2019 ). For example, sexual dimorphism such as body size difference may generate asymmetric physical costs between sexes, resulting in sex-biased dispersal (Gros et al. 2008 ; Trochet et al. 2016 ; Li and Kokko 2019 ). Furthermore, the intra- and inter-sexual competitions play significant roles in the evolution of sex-biased dispersal, where males often compete for access to mates, females for feeding and oviposition sites, and male-female competition will generate sexual conflict in which the dispersal of one sex will benefit the other (Trochet et al. 2013 ). The sex subject to more intense competition is expected to disperse at a higher rate (Perrin and Mazalov 2000 ; Gros et al. 2008 ). These drivers are not mutually exclusive to explain sex-specific dispersal patterns, and multiple mechanisms almost always interact to shape sex-specific dispersal strategies (Gros et al. 2009 ; Li and Kokko 2019 ). Sex-biased dispersal is not necessarily fixed, and both theoretical and empirical evidence indicates that it may vary with changing environmental and social conditions (e.g., Baguette et al. 1998 ; Hovestadt et al. 2014 ; Baines et al. 2017 ; Plazio et al. 2020 ). A theorical model predicts that local male and female densities as well as the relative strength of intra- and inter-sexual competition may alter the sex-specific dispersal probability (Hovestadt et al. 2014 ). Many studies have examined the effect of sex ratio on sex-biased dispersal (e.g., Baguette et al. 1998 ; Baines et al. 2017 ). In a study on dwarf spider, Erigone atra Blackwall, De Meester and Bonte ( 2010 ) showed that female dispersal rate increases with female density, and males tend to disperse under conditions of high male densities coupled with a low female density. Trochet et al. ( 2013 ) found that in Pieris brassicae (L.), female and male emigration rates are higher when population sex ratio is male-biased, which male harassment induces female emigration, while male-male competition promote male emigration. Mishra et al. ( 2020 ) showed that in Drosophila melanogaster Meigen, the dispersal of either sex induces a mate limitation in a local population which increases the dispersal of both sexes, and the increase is considerably greater in males compared to the females. Sex-biased dispersal may also be modulated by total population density. For example, Mishra et al. ( 2018 ) revealed that, at a strict sex ratio of 1♀:1♂, the predominant dispersing sex of D. melanogaster switches from female at low population densities to male at high densities. These suggest that sex-biased dispersal can be plasticity and affected by conditions of social environment, which may profoundly complicate the consequences of dispersal on ecological and evolutionary dynamics. The two-spotted spider mite, Tetranychus urticae Koch (Acari: Tetranychidae), is a notorious invasive pest of global concern, damaging over 1,000 host plant species, including numerous economically important crops (Migeon and Dorkeld 2025 ). It is a haplodiploid species in which unfertilized eggs develop into smaller haploid males and fertilized eggs develop into larger diploid females. Spider mites are r -selected species with short life cycle and high reproductive rate, and their populations exhibit fluctuations in density and sex ratio as the population develops (Mitchell 1973 ). New populations are usually established by a small number of founding females, and they grow rapidly, leading to resource depletion and overcrowding. Females usually disperse to establish new colonies with a female-biased sex ratio (Mitchell 1973 ), e.g., offspring sex ratio is typically 3♀:1♂ (Potter 1978 ). With the increase of population, females would disperse while males tend to stay on the leaf or disperse a short distance (Potter et al. 1976 ; Clotuche et al. 2013 ). The female-biased dispersal may result in a local population sex ratio becoming male-biased, even reaching over 3.3 males per female (Potter 1978 ; Krainacker and Carey 1991 ). In addition, males live longer than females (Li and Zhang 2018 ), which may facilitate population sex ratio fluctuation. Spider mites exhibit frequent dispersal behavior through ballooning and walking, and female is the primary dispersing sex (Yano and Takafuji 2002 ; Ohzora and Yano 2011 ; Bitume et al. 2013 ; Dahirel et al. 2019 ; Santos et al. 2020 ; Zhou et al. 2021 , 2024 ). For example, previous studies revealed that high density increases intrasexual competition resulting in higher emigration and longer dispersal distance of females (Li and Margolies 1993 ; Bitume et al. 2013 ; Azandémè-Hounmalon et al. 2014 ; Zhou et al. 2024 ), and males can also disperse over considerable distances (Krainacker and Carey 1990a ; Clotuche et al. 2013 ). It has been widely demonstrated that multiple mating and male-female interaction are harmful to females, for example, resulting in lower fecundity (Oku 2010 ; Macke et al. 2012 ; Rodrigues et al. 2020 ; Li and Zhang 2021 ), less female-biased offspring (Macke et al. 2012 ; Rodrigues et al. 2020 ), and shortened longevity (Li and Zhang 2021 ). It is thus expected that females will exhibit a stronger dispersal tendency when the population sex ratio is male-biased. However, so far, it is not clear how population densities with various sex ratios affect the dispersal of both sexes in spider mites. Investigations into sex-biased dispersal patterns in relation to population density and sex ratio will enhance our understandings of spider mite population dynamics and provide critical knowledge for developing population management strategies. In this study, we tested ambulatory emigration and dispersal distance of males and females at varying population densities and sex ratios in T. urticae . We set up a factorial design with three population densities and three sex ratios, resulting in nine treatments. We predicted that: (1) increased population density would increase the dispersal of both males and females at a given sex ratio, and (2) female would have higher emigration rate and longer dispersal distance than males across three population sex ratios. We also examined the interactions between sex, population density and sex ratio affecting spider mite dispersal. Materials and methods Mite colony and experimental conditions Tetranychus urticae adults were collected from strawberry Fragaria × ananassa in Anqing, Anhui Province, China, and the colony was maintained on 3- to 5-week-old common bean Phaseolus vulgaris L. (Fabales: Fabaceae) plants grown in pots. Leaf squares cut from the first expanded leaves of 1- to 2-week-old bean plants were used for experiment. We maintained the colony and performed the experiment under the conditions of 25 ± 1 ºC, 40 ± 10% RH, and 14:10 h (L:D) photoperiod. Mite preparation To obtain virgin males, 50 female deutonymphs were randomly selected from the colony and transferred onto a clean fresh leaf square (4 × 4 cm) on wet cotton wool in a Petri dish (9 cm in diameter × 1 cm in height). We prepared 200 such dishes in total. We allowed these deutonymphs in each Petri dish to develop into 3-day-old virgin adult females. Those females were transferred onto a clean leaf square and allowed to lay eggs for 24 hours, after which time they were removed. Eggs laid on leaf squares were allowed to develop to 1-day-old virgin male adults and then used for experiment. To obtain virgin females, 50 adult females were randomly selected from the colony and transferred onto a clean fresh leaf square (4 × 4 cm) on wet cotton wool in a Petri dish to lay eggs for 24 hours, after which time the female adults were removed. We prepared 300 Petri dishes in total. When the mites developed to the deutonymphal stage, female deutonymphs were transferred onto new leaf squares with 50 individuals per leaf square to ensure their virginity. Female deutonymphs were allowed to develop into 1-day-old adults and used for experiment. Dispersal at different densities and sex ratios We designed a dispersal arena containing one starting leaf square (2 cm × 2 cm) and 27 dispersal leaf squares (2 cm × 1 cm) placed on wet cotton in a tray (45 cm length × 36 cm width × 1.5 cm height) (Fig. 1 ). We employed a factorial design with three population densities/sizes (5, 20, 40 mites/cm 2 , corresponding to 20, 80, and 160 mites on the starting leaf square, respectively) and three sex ratios (3♀:1♂, 1♀:1♂, and 1♀:3♂), resulting in nine treatments, with 16/17 replicates for each treatment (Table 1 ). We employed 25,920 mites in total for the experimental trials. The density set up fell into spider mite density in nature which ranges from 0.1 to 50 individuals/cm 2 (Helle and Sabelis 1985 ; Geroh et al. 2010 ). For each replicate, we transferred 1-day-old virgin males and females of a desired number according to treatments onto the starting leaf square and allowed them to settle for 30 minutes. We then connected all leaf squares using Parafilm bridges (4.5 cm length × 1.5 cm width; Parafilm®, USA). We allowed mites to disperse freely for 72 hours, after which time, removed all bridges and counted the number of adults on each leaf square. We then removed all adults and counted the number of eggs on each leaf square. All leaf squares with eggs were individually transferred onto wet cotton in a Petri dish, and the eggs were reared on their original leaf squares until adults to record offspring egg-to-adult survival. Dispersal probability was defined as the percentage of mites that dispersed out of the starting leaf square. We numbered the leaf squares progressively from the starting leaf square to estimate the dispersal distance and regarded the starting leaf square as zero distance. The mean dispersal distance of a replicate was calculated by averaging the dispersal distance of all individuals in the replicate, and the total egg production per replicate was determined by counting eggs on all leaf squares. Mean egg distance was calculated for each replicate through averaging distances of all individual eggs. Offspring survival was estimated as the proportion of eggs developing to adulthood. Table 1 A factorial design showing nine treatments of three sex ratios and population densities Sex ratio Population density (no. of individuals) Treatment Replicate (n) 1♀:3♂ 20 5♀:15♂ 16 80 20♀:60♂ 17 160 40♀:120♂ 17 1♀:1♂ 20 10♀:10♂ 16 80 40♀:40♂ 17 160 80♀:80♂ 16 3♀:1♂ 20 15♀:5♂ 16 80 60♀:20♂ 16 160 120♀:40♂ 17 Statistical analysis We analyzed data using SAS v.9.4 with a reject level set at α = 0.05. We applied a generalized linear model to analyse the effects of fixed factors of sex, sex ratio and population density, and their interactions on five response variables (i.e., dispersal probability, dispersal distance, number of eggs, distance of eggs and offspring survival rate) (GLMMIX procedure). Dispersal probability and offspring survival rate were modeled with a binomial distribution and a logit-link function, while the dispersal distance, number of eggs, and distance of eggs were modeled with a gamma distribution and a log-link function. For offspring survival rate, the number of eggs, and distance of eggs, sex was not included as a fixed factor. Post-hoc pairwise comparisons of least-squares means were conducted using the Tukey-Kramer method. Results Dispersal probability and dispersal distance Dispersal probability was significantly affected by sex and population density, but not by sex ratio alone (Table 2 ; Fig. 2 ). Female T. urticae had a significantly higher dispersal probability than males; however, sex-biased dispersal depended on population density (Fig. 2 a and 2 e), i.e., male and female had similar dispersal probabilities at a lower population density (i.e., 20), but significantly more females dispersed than males at higher population densities (i.e., 80 and 160). Dispersal probability increased significantly with population density, and the significant interaction between sex ratio and population density resulted in a significantly greater dispersal at a higher density of 180 with a sex ratio of 3♀:1♂ (Fig. 2 c and 2 f). No significant interaction was found between sex and sex ratio, or between sex, sex ratio, and population density (Fig. 2 d and 2 g). Table 2 Effect of sex, sex ratio (SR), population density (PD) and their interactions on dispersal probability and distance in T. urticae Effect DF F P Dispersal probability Sex 1, 278 71.07 < 0.0001 SR 2, 278 1.18 0.3097 PD 2, 278 48.75 < 0.0001 Sex*SR 2, 278 2.55 0.0802 Sex*PD 2, 278 9.34 0.0001 SR*PD 4, 278 10.38 < 0.0001 Sex*SR*PD 4, 278 2.24 0.0647 Dispersal distance Sex 1, 272 19.04 < .0001 SR 2, 272 0.77 0.4625 PD 2, 272 20.29 < 0.0001 Sex*SR 2, 272 0.51 0.6025 Sex*PD 2, 272 6.04 0.0027 SR*PD 4, 272 1.29 0.2748 Sex*SR*PD 4, 272 0.39 0.8142 Dispersal distance was significantly affected by sex and population density, but not by sex ratio alone (Table 2 ; Fig. 3 ). Females dispersed a significantly longer distance than males, and dispersal distance increased significantly with population density (Fig. 3 a and 3 c). However, sex-biased dispersal depended on population density (Fig. 3 e), i.e., male and female had similar dispersal distance at low and medium population densities (i.e., 20 and 80), but females dispersed significantly longer than males at high population density (i.e., 160). No significant interaction was found between sex and sex ratio, between sex ratio and population density, or between sex, sex ratio, and population density (Fig. 3 d, 3 f and 3 g). Effect of sex ratio, population density and their interactions on total number of eggs, egg distance, and offspring survival rate The number of eggs laid was significantly higher at a female-biased sex ratio and increased significantly with increasing population density (Table 3 ; Fig. 4 ). Eggs were deposited significantly farther at higher population densities of 80 and 160 than at the lower one, but neither sex ratio nor the interaction between population density and sex ratio had significant impact on egg deposition distance (Table 3 ; Fig. 5 ). A female-biased sex ratio and increasing population density significantly decreased offspring survival rate (Table 3 ; Fig. 6 ). Table 3 Effect of sex ratio (SR), population density (PD) and their interactions on total number of eggs laid, egg deposition distance, and offspring survival rate in T. urticae Effect DF F P No. eggs SR 2, 139 50.80 < 0.0001 PD 2, 139 152.67 < 0.0001 SR*PD 4, 139 0.33 0.8576 Egg distance SR 2, 134 0.74 0.4814 PD 2, 134 9.55 0.0001 SR*PD 4, 134 0.8 0.5249 Offspring survival (%) SR 2, 139 19.17 < 0.0001 PD 2, 139 142.67 < 0.0001 SR*PD 4, 139 11.47 < 0.0001 Discussion Sex-biased dispersal We show that dispersal probability and distance in T. urticae were significantly influenced by sex and population density, but not by sex ratio. Females dispersed more frequently and farther than males, although the strength of this bias varied with density (Table 2 , Figs. 2 and 3 ). This overall tendency toward female-biased dispersal was consistent with previous studies on spider mites (Krainacker and Carey 1990a ; Clotuche et al. 2013 ). Such female-biased dispersal in T. urticae is likely facilitated by differences in physiology and life-history traits that mediate sex-specific costs and benefits of dispersal (Gros et al. 2008 ; Li and Kokko 2019 ). Tetranychus females are much larger than males, with longer legs promoting movement and more energy reserves to withstand starvation and dehydration during dispersal (Li and Zhang 2018 ; Ristyadi et al. 2022 ); therefore, dispersal is likely to be less costly to females. Furthermore, spider mites are r -selected species with high reproductive output and rapid population growth rate, and females frequently experience severe intrasexual competition. Indeed, our results show that the number of females in a population directly determined the number of eggs produced, creating variations in offspring survival rates (Figs. 4 and 6 ). Consequently, the benefits of dispersal may be greater for females, as leaving crowded patches can reduce competition and increase offspring fitness by finding new oviposition sites. Male-male competition and mate finding typically drive male-biased dispersal in many species (Hovestadt et al. 2014 ; Li and Kokko 2019 ); however, spider mite males may experience weaker selection pressure to disperse for mates outside their natal habitats. In Tetranychus mites, males typically guard quiescent deutonymphs and mate immediately upon female emergence (Jiao and Zhang 2025 ). They have high reproductive capacity that is sufficient to inseminate all females within a natal population (Krainacker and Carey 1990b ). For example, a 1-d-old male could inseminate up to 15 females (Krainacker and Carey 1989 ), and mate with five females per day without compromising insemination quality (Krainacker and Carey 1990b ). Most importantly, only the female's first mating is biologically effective (Helle 1967 ; Potter and Wrensch 1978 ; Oku 2008 ; Rodrigues et al. 2020 ; Morita et al. 2021 ). These life-history traits reduce the likelihood of males encountering receptive mates in novel habitats and thus gaining less benefits from dispersal. Nevertheless, a substantial proportion of males also dispersed and spread out over a considerable distance (Figs. 2 and 3 ), indicating that both sexes contribute to population spread. Male mites may still possess excess reproductive capability even under a female-biased sex ratio of 3♀:1♂ as set up in this study, which may motivate them to disperse and search for mates even though the probability of success is low. Effects of population density The dispersal probability and distance of either sex increased significantly with population density (Figs. 2 c, 2 e, 3 c and 3 e) indicating that population density was a strong driver of dispersal in both sexes. These may be due to the increase of intra-sexual competition or inter-sexual conflict with increasing population density (Weerawansha et al. 2020 , 2022 , 2023 ). At a low population density, females and males dispersed at similar rates and distances, while at high densities females dispersed more frequently and farther than males (Figs. 2 e and 3 e), suggesting that increasing density amplifies sex-specific responses to competition, i.e., although both sexes might attempt to disperse from the crowded habitats, females faced significantly greater competitive pressure than males in dense populations. We show that at a low population density of 20 individuals, offspring survival rate was the highest but similar across three sex ratios (Fig. 6 c), suggesting limited offspring competition at this environmental condition. In contrast, the survival rate significantly decreased with increasing population density, and the magnitude of reduction was greater at the female-biased sex ratio (Fig. 6 c), indicating severe offspring competition at high density with a female-biased sex ratio. Therefore, we suggest that increasing density promotes dispersal in both sexes, whereas females respond more strongly because of their greater sensitivity to intense intrasexual competition. Effects of sex ratio In contrast to the effect of population density, sex ratio did not significantly affect dispersal probability or distance, and the interaction between sex and sex ratio was not significant (Table 2 ; Figs. 2 a, 2 b, 2 d, 3 a, 3 b and 3 d), indicating that dispersal in T. urticae was independent of population sex ratio. Theoretical models and empirical studies suggest that individuals should adjust their dispersal behavior in response to the strength of intra- and inter-sexual competition (De Meester and Bonte 2010 ; Nelson and Greeff 2011 ; Hovestadt et al. 2014 ; Lee et al. 2021 ; Cimiotti et al. 2024 ). As shown in Figs. 4 a and 6 a, when population sex ratio shifted towards female bias, females produced significantly more eggs, which led to a significant decrease in offspring survival rate. Females are thus subject to more intense intrasexual competition and expected to have higher dispersal probability and longer dispersal distance in female-biased populations. However, our results show that dispersal probability and distance were similar across female-biased (3♀:1♂), equal (1♀:1♂), and male-biased (1♀:3♂) sex ratios, suggesting that sex ratio may affect dispersal pattern through multiple mechanisms. In our experimental setup, we kept population density constant with varying sex ratios, which means that populations with lower female numbers had proportionally more males. In many species, male harassment is a strong driver of female dispersal (Odendaal et al. 1989 ; Trochet et al. 2013 ; Lee et al. 2021 ; Cimiotti et al. 2024 ). For example, male harassment leads to female emigration at a high male density in a butterfly Proclossiana eunomiu (Baguette et al. 1998 ). In spider mites, male harassment may result in fewer fecundity, less female-biased offspring, and shortened longevity (Oku 2010 ; Macke et al. 2012 ; Rodrigues et al. 2020 ; Li and Zhang 2021 ). Females in populations with equal or male-biased sex ratios may disperse to avoid male harassment. Our results thus suggest that both female intrasexual competition in female-biased populations and male harassment in male-biased populations occurred simultaneously, resulting in consistently higher female dispersal at all sex ratio levels but masking clear sex ratio effects. Fitness consequences of dispersal Dispersal could influence reproductive fitness and population dynamics in several ways, and its consequences in T. urticae are closely tied to the effects of density and sex ratio observed in our study. First, greater dispersal probability and longer dispersal distance allowed individuals to move farther from their natal habitat, and thereby reducing local competition for resources among conspecifics and their offspring. For example, in T. ludeni , females producing more eggs have higher dispersal probability and longer dispersal distance, which reduces offspring competition and increases their fitness (Zhou et al. 2024 ). Similarly, in this study, the higher dispersal probability and longer dispersal distance of females spread eggs over longer distances, which may promote pest outbreak and range expansion. However, despite wider egg distribution, increased egg production from more females still resulted in lower offspring survival (Fig. 6 ), indicating that dispersal cannot fully offset the intense female intrasexual competition. Second, male dispersal, although less extensive, may further affect population dynamics by accompanying females into new patches and affecting the distribution of previously dispersed females, shaping the dispersal outcomes and their fitness consequences. Male-female interactions may also reduce female fecundity and longevity in new habitats (Oku 2010 ; Macke et al. 2012 ; Rodrigues et al. 2020 ; Li and Zhang 2021 ), which warrants further investigation. Conclusion This study demonstrates that dispersal in T. urticae is strongly density-dependent and generally female-biased, but independent of sex ratio. Both sexes dispersed more frequently and farther at higher densities, but females exhibited a stronger response, reflecting the higher costs of competition and greater benefits of dispersal. Female intrasexual competition in female-biased populations and male harassment in male-biased populations likely acted simultaneously, resulting in consistently higher female-biased dispersal at all sex ratio levels. By spreading eggs over wider areas, female dispersal in particular may facilitate colonization, outbreaks, and range expansion. Male dispersal, although less extensive, may reduce fecundity and influence the distribution of females in new habitats. This study highlights the ecological importance of sex-specific dispersal in regulating spider mite population dynamics. Declarations Competing Interests The authors declare no conflicts of interest. Funding The work was supported by the Key Scientific Research Programs of Universities in Anhui Province (2024AH051125; 2024AH051080), the Provincial Graduate Education Quality Engineering Project of Anhui Province (2024yjshhsfkc040), and the Key Laboratory of Biodiversity Conservation and Characteristic Resource Utilization in Southwest Anhui (Wxn202405), and the Engineering Technology Research Center for Aquatic Organism Conservation and Water Ecosystem Restoration in University of Anhui Province (Ss202404). Author Contribution P.Z., X.Z.H. and C.C. conceived and designed the study. P.Z., Y.J.Z., Z.H.W., Y.L.F., J.L. and Z.Y.Z. performed the experiment. P.Z., X.Z.H. and C.C. analysed the data. All authors contributed to manuscript preparation. Acknowledgement We thank Xue Zhao for her assistance with the experiment. Data Availability The datasets generated and analysed during the current study are available from the corresponding author on reasonable request. References Azandémè-Hounmalon GY, Fellous S, Kreiter S, Fiaboe KK, Subramanian S, Kungu M, Martin T (2014) Dispersal behavior of Tetranychus evansi and T. urticae on tomato at several spatial scales and densities: implications for integrated pest management. PLoS ONE 9:e95071. https://doi.org/10.1371/journal.pone.0095071 Baguette M, Vansteenwegen C, Convi I, Nève G (1998) Sex-biased density-dependent migration in a metapopulation of the butterfly Proclossiana eunomia . Acta Oecol 19:17–24. https://doi.org/10.1016/S1146-609X(98)80004-0 Baines CB, Ferzoco IM, McCauley SJ (2017) Sex-biased dispersal is independent of sex ratio in a semiaquatic insect. Behav Ecol Sociobiol 71:119. https://doi.org/10.1007/s00265-017-2348-7 Baines CB, Ferzoco IMC, McCauley SJ (2019) Phenotype-by-environment interactions influence dispersal. J Anim Ecol 88:1263–1274. https://doi.org/10.1111/1365-2656.13008 Bitume EV, Bonte D, Ronce O, Bach F, Flaven E, Olivieri I, Nieberding CM (2013) Density and genetic relatedness increase dispersal distance in a subsocial organism. Ecol Lett 16:430–437. https://doi.org/10.1111/ele.12057 Bonte D, Van Dyck H, Bullock JM, Coulon A, Delgado M, Gibbs M, Lehouck V, Matthysen E, Mustin K, Saastamoinen M, Schtickzelle N, Stevens VM, Vandewoestijne S, Baguette M, Barton K, Benton TG, Chaput-Bardy A, Clobert J, Dytham C, Hovestadt T, Meier CM, Palmer SC, Turlure C, Travis JM (2012) Costs of dispersal. Biol Rev Camb Philos Soc 87:290–312. https://doi.org/10.1111/j.1469-185X.2011.00201.x Chaput-Bardy A, Gregoire A, Baguette M, Pagano A, Secondi J (2010) Condition and phenotype-dependent dispersal in a damselfly, Calopteryx splendens . PLoS ONE 5(5):e10694. https://doi.org/10.1371/journal.pone.0010694 Cimiotti DV, Eberhart-Hertel L, Audevard A, Salas PJG, Gelinaud G, Günther K, Rocha A, Schulz R, van der Winden J, Schmaljohann H, Küpper C (2024) Dispersal in kentish plovers Charadrius alexandrinus : Adult females perform furthest movements. J Ornithol 165:301–314. https://doi.org/10.1007/s10336-023-02120-5 Clobert J, Le Galliard JF, Cote J, Meylan S, Massot M (2009) Informed dispersal, heterogeneity in animal dispersal syndromes and the dynamics of spatially structured populations. Ecol Lett 12:197–209. https://doi.org/10.1111/j.1461-0248.2008.01267.x Clotuche G, Navajas M, Mailleux AC, Hance T (2013) Reaching the ball or missing the flight? collective dispersal in the two-spotted spider mite Tetranychus urticae . PLoS ONE 8(10):e77573. https://doi.org/10.1371/journal.pone.0077573 Dahirel M, Masier S, Renault D, Bonte D (2019) The distinct phenotypic signatures of dispersal and stress in an arthropod model: from physiology to life history. J Exp Biol 222(16):jeb203596. https://doi.org/10.1242/jeb.203596 Dahirel M, Vardakis M, Ansart A, Madec L (2016) Density-dependence across dispersal stages in a hermaphrodite land snail: insights from discrete choice models. Oecologia 181:1117–1128. https://doi.org/10.1007/s00442-016-3636-z De Meester N, Bonte D (2010) Information use and density-dependent emigration in an agrobiont spider. Behav Ecol 21:992–998. https://doi.org/10.1093/beheco/arq088 Franckowiak RP, Ridgway MS, Wilson CC (2025) Natal philopatry and sex-biased dispersal in a nest defence mating system. Anim Behav 225:123211. https://doi.org/10.1016/j.anbehav.2025.123211 Geroh M, Gulati R, Sharma S, Kaushik H, Aneja D (2010) Effect of abiotic stresses on population build up of Tetranychus urticae Koch and its predator, Stethorus punctillum weise on okra. Ann Plant Prot Sci 18:108–113. https://www.cabidigitallibrary.org/doi/full/ 10.5555/20103164554 Gros A, Hovestadt T, Poethke HJ (2008) Evolution of sex-biased dispersal: the role of sex-specific dispersal costs, demographic stochasticity, and inbreeding. Ecol Model 219:226–233. https://doi.org/10.1016/j.ecolmodel.2008.08.014 Gros A, Poethke HJ, Hovestadt T (2009) Sex-specific spatio-temporal variability in reproductive success promotes the evolution of sex-biased dispersal. Theor Popul Biol 76:13–18. https://doi.org/10.1016/j.tpb.2009.03.002 Helle W (1967) Fertilization in the two-spotted spider mite ( Tetranychus urticae : Acari). Entomol Exp Appl 10:103–110. https://doi.org/10.1111/j.1570-7458.1967.tb00049.x Helle W, Sabelis MW (1985) Spider mites: Their biology, natural enemies and control. Amsterdam, Netherlands, Elsevier Hewison AJM, Gaillard JM, Morellet N, Cagnacci F, Debeffe L, Cargnelutti B, Gehr B, Kroschel M, Heurich M, Coulon A, Kjellander P, Borger L, Focardi S (2021) Sex differences in condition dependence of natal dispersal in a large herbivore: dispersal propensity and distance are decoupled. Proc R Soc B 288:20202947. https://doi.org/10.1098/rspb.2020.2947 Hovestadt T, Mitesser O, Poethke H-J (2014) Gender-specific emigration decisions sensitive to local male and female density. Am Nat 184:38–51. https://doi.org/10.1086/676524 Jiao A, Zhang Z-Q (2025) Precopulatory guarding of old and young quiescent deutonymph females by adult male Tetranychus evansi (Acari: Tetranychidae). Syst Appl Acarol 30:835–838. https://doi.org/10.11158/saa.30.5.1 Johnstone RA, Cant MA, Field J (2012) Sex-biased dispersal, haplodiploidy and the evolution of helping in social insects. Proc R Soc B 279:787–793. https://doi.org/10.1098/rspb.2011.1257 Krainacker D, Carey J (1989) Reproductive limits and heterogeneity of male twospotted spider mites. Entomol Exp Appl 50:209–214. https://doi.org/10.1111/j.1570-7458.1989.tb01194.x Krainacker DA, Carey JR (1990a) Ambulatory dispersal and life history response to food deprivation in twospotted spider mites. Entomol Exp Appl 56:139–144. https://doi.org/10.1111/j.1570-7458.1990.tb01391.x Krainacker DA, Carey JR (1990b) Male demographic constraints to extreme sex ratio in the twospotted spider mite. Oecologia 82:417–423. https://doi.org/10.1007/BF00317492 Krainacker DA, Carey JR (1991) Sex ratio in a wild population of twospotted spider mites. Ecography 14:97–103. https://doi.org/10.1111/j.1600-0587.1991.tb00639.x Laska A, Rector BG, Przychodzka A, Majer A, Zalewska K, Kuczynski L, Skoracka A (2023) Do mites eat and run? A systematic review of feeding and dispersal strategies. Zool J Linn Soc 198:462–475. https://doi.org/10.1093/zoolinnean/zlac094 Lee MR, Udina CS, Hansson LA (2021) Fear of sex: sexual conflict exposed as avoidance in a parthenogenetic invertebrate. Behav Ecol Sociobiol 75:115. https://doi.org/10.1007/s00265-021-03054-9 Li G-Y, Zhang Z-Q (2018) Does size matter? Fecundity and longevity of spider mites ( Tetranychus urticae ) in relation to mating and food availability. Syst Appl Acarol 23:1796–1808. https://doi.org/10.11158/saa.23.9.6 Li G-Y, Zhang Z-Q (2021) The costs of social interaction on survival and reproduction of arrhenotokous spider mite Tetranychus urticae . Entomol Gen 41:49–57. https://doi.org/10.1127/entomologia/2020/0911 Li J, Margolies DC (1993) Effects of mite age, mite density, and host quality on aerial dispersal behavior in the twospotted spider mite. Entomol Exp Appl 68:79–86. https://doi.org/10.1111/j.1570-7458.1993.tb01691.x Li XY, Kokko H (2019) Sex-biased dispersal: a review of the theory. Biol Rev 94:721–736. https://doi.org/10.1111/brv.12475 Macke E, Magalhaes S, Do-Thi Khanh H, Frantz A, Facon B, Olivieri I (2012) Mating modifies female life history in a haplodiploid spider mite. Am Nat 179:147–162. https://doi.org/10.1086/665002 Matthysen E (2012) Multicausality of dispersal: a review. In: Clobert J, Baguette M, Benton TG, Bullock JM (eds) Dispersal ecology and evolution. Oxford University Press, London, pp 3–18 Migeon A, Dorkeld F (2025) Spider mites web: a comprehensive database for the tetranychidae. http://www1.Montpellier.Inra.Fr/cbgp/spmweb . Accessed 3 August 2025 Mishra A, Tung S, Sruti VRS, Srivathsa S, Dey S (2020) Mate-finding dispersal reduces local mate limitation and sex bias in dispersal. J Anim Ecol 89:2089–2098. https://doi.org/10.1111/1365-2656.13278 Mishra A, Tung S, Sruti VS, Sadiq MA, Srivathsa S, Dey S (2018) Pre-dispersal context and presence of opposite sex modulate density dependence and sex bias of dispersal. Oikos 127:1596–1604. https://doi.org/10.1111/oik.04902 Mitchell R (1973) Growth and population dynamics of a spider mite ( Tetranychus urticae K., Acarina: Tetranychidae). Ecology 54:1349–1355. https://doi.org/10.2307/1934198 Morita A, Ullah MS, Sugawara R, Gotoh T (2021) Effects of male and female age on mating success in Tetranychus urticae Koch (Acari: Tetranychidae). Syst Appl Acarol 26:1280–1292. https://doi.org/10.11158/saa.26.7.8 Nelson RM, Greeff JM (2011) Sex ratio dependent dispersal when sex ratios vary between patches. J Theor Biol 290:81–87. https://doi.org/10.1016/j.jtbi.2011.08.030 Odendaal FJ, Turchin P, Stermitz FR (1989) Influence of host-plant density and male harassment on the distribution of female Euphydryas anicia (nymphalidae). Oecologia 78:283–288. https://doi.org/10.1007/BF00377167 Ohzora Y, Yano S (2011) Voluntary falling in spider mites in response to different ecological conditions at landing points. J Insect Behav 24:274–281. https://doi.org/10.1007/s10905-010-9253-5 Oku K (2008) Is only the first mating effective for females in the kanzawa spider mite, Tetranychus kanzawai (Acari: Tetranychidae)? Exp Appl Acarol 45:53–57. https://doi.org/10.1007/s10493-008-9157-7 Oku K (2010) Males of the two-spotted spider mite attempt to copulate with mated females: Effects of double mating on fitness of either sex. Exp Appl Acarol 50:107–113. https://doi.org/10.1007/s10493-009-9306-7 Perrin N, Mazalov V (2000) Local competition, inbreeding, and the evolution of sex-biased dispersal. Am Nat 155:116–127. https://doi.org/10.1086/303296 Plazio E, Margol T, Nowicki P (2020) Intersexual differences in density-dependent dispersal and their evolutionary drivers. J Evol Biol 33:1495–1506. https://doi.org/10.1111/jeb.13688 Potter DA (1978) Functional sex ratio in the carmine spider mite. Ann Entomol Soc Am 71:218–222. https://doi.org/10.1093/aesa/71.2.218 Potter DA, Wrensch DL (1978) Interrupted matings and the effectiveness of second inseminations in the twospotted spider mite. Ann Entomol Soc Am 71:882–885. https://doi.org/10.1093/aesa/71.6.882 Potter DA, Wrensch DL, Johnston DE (1976) Guarding, aggressive behavior, and mating success in male twospotted spider mites. Ann Entomol Soc Am 69:707–711. https://doi.org/10.1093/aesa/69.4.707 Renault D (2020) A review of the phenotypic traits associated with insect dispersal polymorphism, and experimental designs for sorting out resident and disperser phenotypes. Insects 11:214. https://doi.org/10.3390/insects11040214 Ristyadi D, He XZ, Wang Q (2022) Resource allocation strategies for survival and reproduction by an invasive pest in response to intermittent fasting. Curr Zool 69:600–606. https://doi.org/10.1093/cz/zoac068 Rodrigues LR, Figueiredo ART, Van Leeuwen T, Olivieri I, Magalhaes S (2020) Costs and benefits of multiple mating in a species with first-male sperm precedence. J Anim Ecol 89:1045–1054. https://doi.org/10.1111/1365-2656.13171 Santini L, Fernando M, Mancini G, Di Marco M (2025) The neglected role of sex-biased dispersal in range-shift prediction under climate change. Divers Distrib 31:e13942. https://doi.org/10.1111/ddi.13942 Santos FA, Rolim GS, Nachman GS, Andrade DJ (2020) Using mathematical models to describe aerial dispersal and silk ball formation of peanut red spider mite, Tetranychus ogmophallos (Acari: Tetranychidae). Exp Appl Acarol 81:85–102. https://doi.org/10.1007/s10493-020-00495-1 Trochet A, Courtois EA, Stevens VM, Baguette M, Chaine A, Schmeller DS, Clobert J, Wiens JJ (2016) Evolution of sex-biased dispersal. Q Rev Biol 91:297–320. https://doi.org/10.1086/688097 Trochet A, Legrand D, Larranaga N, Ducatez S, Calvez O, Cote J, Clobert J, Baguette M (2013) Population sex ratio and dispersal in experimental, two-patch metapopulations of butterflies. J Anim Ecol 82:946–955. https://doi.org/10.1111/1365-2656.12082 Weerawansha N, Wang Q, He XZ (2020) Effect of foundress population density and size on reproduction and population growth of a haplodiploid mite. Syst Appl Acarol 25:2063–2076. https://doi.org/10.11158/saa.25.11.11 Weerawansha N, Wang Q, He XZ (2022) A haplodiploid mite adjusts fecundity and sex ratio in response to density changes during the reproductive period. Exp Appl Acarol 88:277–288. https://doi.org/10.1007/s10493-022-00749-0 Weerawansha N, Wang Q, He XZ (2023) Reproductive plasticity in response to the changing cluster size during the breeding period: a case study in a spider mite. Exp Appl Acarol 91:237–250. https://doi.org/10.1007/s10493-023-00834-y Yano S, Takafuji A (2002) Variation in the life history pattern of Tetranychus urticae (Acari: Tetranychidae) after selection for dispersal. Exp Appl Acarol 27:1–10. https://doi.org/10.1023/A:1021518221031 Zhou P, He XZ, Chen C, Wang Q (2021) Resource relocations in relation to dispersal in Tetranychus ludeni Zacher. Syst Appl Acarol 26:2018–2026. https://doi.org/10.11158/saa.26.11.3 Zhou P, He XZ, Chen C, Wang Q (2024) Age and density of mated females affect dispersal strategies in spider mite Tetranychus ludeni Zacher. Insects 15:387. https://doi.org/10.3390/insects15060387 Zsinka B, Kövér S, Horváth M, Vili N, Szabó-Csonka V, Szabó K, Pásztory-Kovács S (2025) Sex-biased and density-dependent natal dispersal in a highly mobile but philopatric raptor. Ecol Evol 15:e71487. https://doi.org/10.1002/ece3.71487 Additional Declarations No competing interests reported. Cite Share Download PDF Status: Posted Version 1 posted You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-7472280","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":513594523,"identity":"d1b13373-ec26-4900-8a2e-cc447c1de06b","order_by":0,"name":"Peng Zhou","email":"","orcid":"","institution":"Anqing Normal University","correspondingAuthor":false,"prefix":"","firstName":"Peng","middleName":"","lastName":"Zhou","suffix":""},{"id":513594524,"identity":"2e7b53b1-9462-425c-9172-1c4c78d108f0","order_by":1,"name":"Yujie Zhang","email":"","orcid":"","institution":"Anqing Normal University","correspondingAuthor":false,"prefix":"","firstName":"Yujie","middleName":"","lastName":"Zhang","suffix":""},{"id":513594525,"identity":"ba04dda7-4ae7-4511-a480-814a527b7928","order_by":2,"name":"Xiong Zhao He","email":"","orcid":"","institution":"Massey University","correspondingAuthor":false,"prefix":"","firstName":"Xiong","middleName":"Zhao","lastName":"He","suffix":""},{"id":513594526,"identity":"a24ba2e2-6738-4e76-ab54-10f90756368b","order_by":3,"name":"Zhihan Wang","email":"","orcid":"","institution":"Anqing Normal University","correspondingAuthor":false,"prefix":"","firstName":"Zhihan","middleName":"","lastName":"Wang","suffix":""},{"id":513594527,"identity":"3e45d399-484a-4ab8-9ace-217ccff7b032","order_by":4,"name":"Yalin Fan","email":"","orcid":"","institution":"Anqing Normal University","correspondingAuthor":false,"prefix":"","firstName":"Yalin","middleName":"","lastName":"Fan","suffix":""},{"id":513594528,"identity":"058d461a-676c-4b7d-8728-c0c5275c32f0","order_by":5,"name":"Jing Ling","email":"","orcid":"","institution":"Anqing Normal University","correspondingAuthor":false,"prefix":"","firstName":"Jing","middleName":"","lastName":"Ling","suffix":""},{"id":513594529,"identity":"b5c1cd51-902c-465f-9a6d-f465c6b2c4ce","order_by":6,"name":"Ziyue Zhang","email":"","orcid":"","institution":"Anqing Normal University","correspondingAuthor":false,"prefix":"","firstName":"Ziyue","middleName":"","lastName":"Zhang","suffix":""},{"id":513594530,"identity":"8b2bc194-09a1-466d-8244-2757485301b0","order_by":7,"name":"Chen Chen","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA+ElEQVRIie3RMUsDMRTA8XccdErJ0CWhfoh0SSkc9as0HMTl0MHlxhyBTO2e4vcQN3McdArtKtThQHC+LkJB0HPXtODSIT9445/HSwCi6BKRfhIFgHFVtV2ZIYzVmQm1TTOxXl5R685MmJNyNDRNxtQiXOAHvWmPT9ktOM8B+R1i4JLuUASWvG5uJisv7xO95C0p92iaqpSuH/9OGCn4ODGN0OCnjPk9mik3SIfB5O6jT76EgYITYbaIucWppBj0iRNLkJLUxp1OyIvkdGVyYUn/yMrniNpaB2/BNn8nRzMXz7uqevss59cY67o7BJLf/HxTFEVR9C/fx7ZY5h6ezsIAAAAASUVORK5CYII=","orcid":"","institution":"Anqing Normal University","correspondingAuthor":true,"prefix":"","firstName":"Chen","middleName":"","lastName":"Chen","suffix":""}],"badges":[],"createdAt":"2025-08-27 13:53:12","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-7472280/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-7472280/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":91371652,"identity":"47ad2b65-c311-417c-b457-c4b56fa1c6cb","added_by":"auto","created_at":"2025-09-15 18:52:18","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":77912,"visible":true,"origin":"","legend":"\u003cp\u003eDispersal arena for experiment, which contains a starting leaf square (2 cm × 2 cm) for introducing experimental mites and 27 dispersal leaf squares (2 cm × 1 cm). Parafilm bridges were used to connect adjacent leaf squares, with approximately 1 mm overlapping to minimize the impact of water on mite dispersal\u003c/p\u003e","description":"","filename":"1.png","url":"https://assets-eu.researchsquare.com/files/rs-7472280/v1/449a6ca95b3e7a78b7478788.png"},{"id":91371653,"identity":"8a886d52-8aa8-4257-b800-2d8216a83638","added_by":"auto","created_at":"2025-09-15 18:52:18","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":334420,"visible":true,"origin":"","legend":"\u003cp\u003eDispersal probability (mean ± SE) of \u003cem\u003eT. urticae\u003c/em\u003e affected by sex (a), sex ratios (SR) (b), population densities (PD) (c), and their interactions of sex and sex ratio (Sex*SR) (d), sex and population density (Sex*PD) (e), sex ratio and population density (SR*PD) (f), and sex, sex ratio and population density (Sex*SR*PD) (g). For a given category, columns with the same letters are not significantly different (\u003cem\u003eP\u003c/em\u003e \u0026gt; 0.05)\u003c/p\u003e","description":"","filename":"2.png","url":"https://assets-eu.researchsquare.com/files/rs-7472280/v1/ba1df944485ec6e98bbe7a3e.png"},{"id":91371656,"identity":"bc4c687a-c89b-4ea0-94ca-896f57392db6","added_by":"auto","created_at":"2025-09-15 18:52:18","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":729112,"visible":true,"origin":"","legend":"\u003cp\u003eDispersal distance (mean ± SE) of \u003cem\u003eT. urticae\u003c/em\u003eaffected by sex (a), sex ratios (SR) (b), population densities (PD) (c), and their interactions of sex and sex ratio (Sex*SR) (d), sex and population density (Sex*PD) (e), sex ratio and population density (SR*PD) (f), and sex, sex ratio and population density (Sex*SR*PD) (g). For a given category, columns with the same letters are not significantly different (\u003cem\u003eP\u003c/em\u003e \u0026gt; 0.05)\u003c/p\u003e","description":"","filename":"3.png","url":"https://assets-eu.researchsquare.com/files/rs-7472280/v1/b7f2fdf9ad634548252eae33.png"},{"id":91372889,"identity":"b45c7420-c782-4138-8d71-50e51534ad66","added_by":"auto","created_at":"2025-09-15 19:08:19","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":182928,"visible":true,"origin":"","legend":"\u003cp\u003eTotal number of eggs (mean ± SE) of \u003cem\u003eT. urticae\u003c/em\u003e affected by sex ratios (SR) (a), population densities (PD) (b), and their interactions (SR*PD) (c). For a given category, columns with the same letters are not significantly different (\u003cem\u003eP\u003c/em\u003e \u0026gt; 0.05)\u003c/p\u003e","description":"","filename":"4.png","url":"https://assets-eu.researchsquare.com/files/rs-7472280/v1/c25b1cf0b840cf33ac15d668.png"},{"id":91372883,"identity":"a76d4883-b786-49d9-ab89-308b1b606833","added_by":"auto","created_at":"2025-09-15 19:08:19","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":174272,"visible":true,"origin":"","legend":"\u003cp\u003eEgg distance (mean ± SE) of \u003cem\u003eT. urticae\u003c/em\u003e affected by sex ratios (SR) (a), population densities (PD) (b), and their interactions (SR*PD) (c). For a given category, columns with the same letters are not significantly different (\u003cem\u003eP\u003c/em\u003e \u0026gt; 0.05)\u003c/p\u003e","description":"","filename":"5.png","url":"https://assets-eu.researchsquare.com/files/rs-7472280/v1/0372a9922f7919eefe49cd01.png"},{"id":91372459,"identity":"742be2a3-5bf1-488f-bec0-6b6e2d427dab","added_by":"auto","created_at":"2025-09-15 19:00:19","extension":"png","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":178256,"visible":true,"origin":"","legend":"\u003cp\u003eOffspring survival rate (mean ± SE) of \u003cem\u003eT. urticae\u003c/em\u003e affected by sex ratios (SR) (a), population densities (PD) (b), and their interactions (SR*PD) (c). For a given category, columns with the same letters are not significantly different (\u003cem\u003eP\u003c/em\u003e \u0026gt; 0.05)\u003c/p\u003e","description":"","filename":"6.png","url":"https://assets-eu.researchsquare.com/files/rs-7472280/v1/89cdcf218c81e71ac6c3ba89.png"},{"id":99788174,"identity":"56d22f1d-f407-4ff4-bbae-bd6481fc52b1","added_by":"auto","created_at":"2026-01-08 12:45:31","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":2590619,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-7472280/v1/533afd5f-8eb7-40ec-bab7-c792b0818e29.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"\u003cp\u003eSex-biased dispersal in \u003cem\u003eTetranychus urticae\u003c/em\u003e mediated by population density but independent of sex ratio\u003c/p\u003e","fulltext":[{"header":"Introduction","content":"\u003cp\u003eDispersal is often described as a three-stage process involving emigration, inter-patch movement, and immigration, each of which is influenced by both intrinsic phenotypes and extrinsic environmental conditions (Clobert et al. \u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e2009\u003c/span\u003e; Bonte et al. \u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e2012\u003c/span\u003e; Matthysen \u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e2012\u003c/span\u003e; Baines et al. \u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e2019\u003c/span\u003e). Therefore, an individual\u0026rsquo;s dispersal decision and ability are influenced by intrinsic factors such as sex and body condition, and extrinsic environmental conditions including population density, sex ratio, and resource availability (Matthysen \u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e2012\u003c/span\u003e; Laska et al. \u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e2023\u003c/span\u003e). Among the factors influencing dispersal, their effects on emigration may differ in magnitude or direction compared to those affecting subsequent movement and immigration (Chaput-Bardy et al. \u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e2010\u003c/span\u003e; Matthysen \u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e2012\u003c/span\u003e; Dahirel et al. \u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e2016\u003c/span\u003e; Hewison et al. \u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e2021\u003c/span\u003e). To date, previous studies on factors affecting dispersal process mostly focused on emigration (e.g., De Meester and Bonte \u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e2010\u003c/span\u003e; Baines et al. \u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e2017\u003c/span\u003e; Mishra et al. \u003cspan citationid=\"CR37\" class=\"CitationRef\"\u003e2020\u003c/span\u003e), how different environmental factors may affect dispersal, such as distance, oviposition, and egg/offspring distribution is largely unexplored. A better understanding of how phenotypic and ecological factors affect the dispersal processes is critical for predicting pest population dynamics (Matthysen \u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e2012\u003c/span\u003e; Renault \u003cspan citationid=\"CR51\" class=\"CitationRef\"\u003e2020\u003c/span\u003e; Santini et al. \u003cspan citationid=\"CR54\" class=\"CitationRef\"\u003e2025\u003c/span\u003e) and developing pest management strategies.\u003c/p\u003e\u003cp\u003eSex is among the most important phenotypic drivers influencing dispersal, with sex-specific patterns reported across diverse taxonomic groups (Johnstone et al. \u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e2012\u003c/span\u003e; Trochet et al. \u003cspan citationid=\"CR56\" class=\"CitationRef\"\u003e2016\u003c/span\u003e; Li and Kokko \u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e2019\u003c/span\u003e; Franckowiak et al. \u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e2025\u003c/span\u003e; Zsinka et al. \u003cspan citationid=\"CR64\" class=\"CitationRef\"\u003e2025\u003c/span\u003e). Several evolutionary mechanisms have been involved in explaining sex-biased dispersal, such as inbreeding avoidance, kin competition, parental care, sexual dimorphism, asymmetries in dispersal costs or benefits, and intra- and intersexual competition (Perrin and Mazalov \u003cspan citationid=\"CR46\" class=\"CitationRef\"\u003e2000\u003c/span\u003e; Gros et al. \u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e2008\u003c/span\u003e, \u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e2009\u003c/span\u003e; Bonte et al. \u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e2012\u003c/span\u003e; Li and Kokko \u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e2019\u003c/span\u003e). For example, sexual dimorphism such as body size difference may generate asymmetric physical costs between sexes, resulting in sex-biased dispersal (Gros et al. \u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e2008\u003c/span\u003e; Trochet et al. \u003cspan citationid=\"CR56\" class=\"CitationRef\"\u003e2016\u003c/span\u003e; Li and Kokko \u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e2019\u003c/span\u003e). Furthermore, the intra- and inter-sexual competitions play significant roles in the evolution of sex-biased dispersal, where males often compete for access to mates, females for feeding and oviposition sites, and male-female competition will generate sexual conflict in which the dispersal of one sex will benefit the other (Trochet et al. \u003cspan citationid=\"CR57\" class=\"CitationRef\"\u003e2013\u003c/span\u003e). The sex subject to more intense competition is expected to disperse at a higher rate (Perrin and Mazalov \u003cspan citationid=\"CR46\" class=\"CitationRef\"\u003e2000\u003c/span\u003e; Gros et al. \u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e2008\u003c/span\u003e). These drivers are not mutually exclusive to explain sex-specific dispersal patterns, and multiple mechanisms almost always interact to shape sex-specific dispersal strategies (Gros et al. \u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e2009\u003c/span\u003e; Li and Kokko \u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e2019\u003c/span\u003e).\u003c/p\u003e\u003cp\u003eSex-biased dispersal is not necessarily fixed, and both theoretical and empirical evidence indicates that it may vary with changing environmental and social conditions (e.g., Baguette et al. \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e1998\u003c/span\u003e; Hovestadt et al. \u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e2014\u003c/span\u003e; Baines et al. \u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e2017\u003c/span\u003e; Plazio et al. \u003cspan citationid=\"CR47\" class=\"CitationRef\"\u003e2020\u003c/span\u003e). A theorical model predicts that local male and female densities as well as the relative strength of intra- and inter-sexual competition may alter the sex-specific dispersal probability (Hovestadt et al. \u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e2014\u003c/span\u003e). Many studies have examined the effect of sex ratio on sex-biased dispersal (e.g., Baguette et al. \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e1998\u003c/span\u003e; Baines et al. \u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e2017\u003c/span\u003e). In a study on dwarf spider, \u003cem\u003eErigone atra\u003c/em\u003e Blackwall, De Meester and Bonte (\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e2010\u003c/span\u003e) showed that female dispersal rate increases with female density, and males tend to disperse under conditions of high male densities coupled with a low female density. Trochet et al. (\u003cspan citationid=\"CR57\" class=\"CitationRef\"\u003e2013\u003c/span\u003e) found that in \u003cem\u003ePieris brassicae\u003c/em\u003e (L.), female and male emigration rates are higher when population sex ratio is male-biased, which male harassment induces female emigration, while male-male competition promote male emigration. Mishra et al. (\u003cspan citationid=\"CR37\" class=\"CitationRef\"\u003e2020\u003c/span\u003e) showed that in \u003cem\u003eDrosophila melanogaster\u003c/em\u003e Meigen, the dispersal of either sex induces a mate limitation in a local population which increases the dispersal of both sexes, and the increase is considerably greater in males compared to the females. Sex-biased dispersal may also be modulated by total population density. For example, Mishra et al. (\u003cspan citationid=\"CR38\" class=\"CitationRef\"\u003e2018\u003c/span\u003e) revealed that, at a strict sex ratio of 1♀:1♂, the predominant dispersing sex of \u003cem\u003eD. melanogaster\u003c/em\u003e switches from female at low population densities to male at high densities. These suggest that sex-biased dispersal can be plasticity and affected by conditions of social environment, which may profoundly complicate the consequences of dispersal on ecological and evolutionary dynamics.\u003c/p\u003e\u003cp\u003eThe two-spotted spider mite, \u003cem\u003eTetranychus urticae\u003c/em\u003e Koch (Acari: Tetranychidae), is a notorious invasive pest of global concern, damaging over 1,000 host plant species, including numerous economically important crops (Migeon and Dorkeld \u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e2025\u003c/span\u003e). It is a haplodiploid species in which unfertilized eggs develop into smaller haploid males and fertilized eggs develop into larger diploid females. Spider mites are \u003cem\u003er\u003c/em\u003e-selected species with short life cycle and high reproductive rate, and their populations exhibit fluctuations in density and sex ratio as the population develops (Mitchell \u003cspan citationid=\"CR39\" class=\"CitationRef\"\u003e1973\u003c/span\u003e). New populations are usually established by a small number of founding females, and they grow rapidly, leading to resource depletion and overcrowding. Females usually disperse to establish new colonies with a female-biased sex ratio (Mitchell \u003cspan citationid=\"CR39\" class=\"CitationRef\"\u003e1973\u003c/span\u003e), e.g., offspring sex ratio is typically 3♀:1♂ (Potter \u003cspan citationid=\"CR49\" class=\"CitationRef\"\u003e1978\u003c/span\u003e). With the increase of population, females would disperse while males tend to stay on the leaf or disperse a short distance (Potter et al. \u003cspan citationid=\"CR50\" class=\"CitationRef\"\u003e1976\u003c/span\u003e; Clotuche et al. \u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e2013\u003c/span\u003e). The female-biased dispersal may result in a local population sex ratio becoming male-biased, even reaching over 3.3 males per female (Potter \u003cspan citationid=\"CR49\" class=\"CitationRef\"\u003e1978\u003c/span\u003e; Krainacker and Carey \u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e1991\u003c/span\u003e). In addition, males live longer than females (Li and Zhang \u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e2018\u003c/span\u003e), which may facilitate population sex ratio fluctuation.\u003c/p\u003e\u003cp\u003eSpider mites exhibit frequent dispersal behavior through ballooning and walking, and female is the primary dispersing sex (Yano and Takafuji \u003cspan citationid=\"CR61\" class=\"CitationRef\"\u003e2002\u003c/span\u003e; Ohzora and Yano \u003cspan citationid=\"CR43\" class=\"CitationRef\"\u003e2011\u003c/span\u003e; Bitume et al. \u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e2013\u003c/span\u003e; Dahirel et al. \u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e2019\u003c/span\u003e; Santos et al. \u003cspan citationid=\"CR55\" class=\"CitationRef\"\u003e2020\u003c/span\u003e; Zhou et al. \u003cspan citationid=\"CR62\" class=\"CitationRef\"\u003e2021\u003c/span\u003e, \u003cspan citationid=\"CR63\" class=\"CitationRef\"\u003e2024\u003c/span\u003e). For example, previous studies revealed that high density increases intrasexual competition resulting in higher emigration and longer dispersal distance of females (Li and Margolies \u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e1993\u003c/span\u003e; Bitume et al. \u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e2013\u003c/span\u003e; Azand\u0026eacute;m\u0026egrave;-Hounmalon et al. \u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e2014\u003c/span\u003e; Zhou et al. \u003cspan citationid=\"CR63\" class=\"CitationRef\"\u003e2024\u003c/span\u003e), and males can also disperse over considerable distances (Krainacker and Carey \u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e1990a\u003c/span\u003e; Clotuche et al. \u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e2013\u003c/span\u003e). It has been widely demonstrated that multiple mating and male-female interaction are harmful to females, for example, resulting in lower fecundity (Oku \u003cspan citationid=\"CR45\" class=\"CitationRef\"\u003e2010\u003c/span\u003e; Macke et al. \u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e2012\u003c/span\u003e; Rodrigues et al. \u003cspan citationid=\"CR53\" class=\"CitationRef\"\u003e2020\u003c/span\u003e; Li and Zhang \u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e2021\u003c/span\u003e), less female-biased offspring (Macke et al. \u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e2012\u003c/span\u003e; Rodrigues et al. \u003cspan citationid=\"CR53\" class=\"CitationRef\"\u003e2020\u003c/span\u003e), and shortened longevity (Li and Zhang \u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e2021\u003c/span\u003e). It is thus expected that females will exhibit a stronger dispersal tendency when the population sex ratio is male-biased. However, so far, it is not clear how population densities with various sex ratios affect the dispersal of both sexes in spider mites. Investigations into sex-biased dispersal patterns in relation to population density and sex ratio will enhance our understandings of spider mite population dynamics and provide critical knowledge for developing population management strategies.\u003c/p\u003e\u003cp\u003eIn this study, we tested ambulatory emigration and dispersal distance of males and females at varying population densities and sex ratios in \u003cem\u003eT. urticae\u003c/em\u003e. We set up a factorial design with three population densities and three sex ratios, resulting in nine treatments. We predicted that: (1) increased population density would increase the dispersal of both males and females at a given sex ratio, and (2) female would have higher emigration rate and longer dispersal distance than males across three population sex ratios. We also examined the interactions between sex, population density and sex ratio affecting spider mite dispersal.\u003c/p\u003e"},{"header":"Materials and methods","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e\u003ch2\u003eMite colony and experimental conditions\u003c/h2\u003e\u003cp\u003e\u003cem\u003eTetranychus urticae\u003c/em\u003e adults were collected from strawberry \u003cem\u003eFragaria \u0026times; ananassa\u003c/em\u003e in Anqing, Anhui Province, China, and the colony was maintained on 3- to 5-week-old common bean \u003cem\u003ePhaseolus vulgaris\u003c/em\u003e L. (Fabales: Fabaceae) plants grown in pots. Leaf squares cut from the first expanded leaves of 1- to 2-week-old bean plants were used for experiment. We maintained the colony and performed the experiment under the conditions of 25\u0026thinsp;\u0026plusmn;\u0026thinsp;1 \u0026ordm;C, 40\u0026thinsp;\u0026plusmn;\u0026thinsp;10% RH, and 14:10 h (L:D) photoperiod.\u003c/p\u003e\u003c/div\u003e\n\u003ch3\u003eMite preparation\u003c/h3\u003e\n\u003cp\u003eTo obtain virgin males, 50 female deutonymphs were randomly selected from the colony and transferred onto a clean fresh leaf square (4 \u0026times; 4 cm) on wet cotton wool in a Petri dish (9 cm in diameter \u0026times; 1 cm in height). We prepared 200 such dishes in total. We allowed these deutonymphs in each Petri dish to develop into 3-day-old virgin adult females. Those females were transferred onto a clean leaf square and allowed to lay eggs for 24 hours, after which time they were removed. Eggs laid on leaf squares were allowed to develop to 1-day-old virgin male adults and then used for experiment. To obtain virgin females, 50 adult females were randomly selected from the colony and transferred onto a clean fresh leaf square (4 \u0026times; 4 cm) on wet cotton wool in a Petri dish to lay eggs for 24 hours, after which time the female adults were removed. We prepared 300 Petri dishes in total. When the mites developed to the deutonymphal stage, female deutonymphs were transferred onto new leaf squares with 50 individuals per leaf square to ensure their virginity. Female deutonymphs were allowed to develop into 1-day-old adults and used for experiment.\u003c/p\u003e\n\u003ch3\u003eDispersal at different densities and sex ratios\u003c/h3\u003e\n\u003cp\u003eWe designed a dispersal arena containing one starting leaf square (2 cm \u0026times; 2 cm) and 27 dispersal leaf squares (2 cm \u0026times; 1 cm) placed on wet cotton in a tray (45 cm length \u0026times; 36 cm width \u0026times; 1.5 cm height) (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e). We employed a factorial design with three population densities/sizes (5, 20, 40 mites/cm\u003csup\u003e2\u003c/sup\u003e, corresponding to 20, 80, and 160 mites on the starting leaf square, respectively) and three sex ratios (3♀:1♂, 1♀:1♂, and 1♀:3♂), resulting in nine treatments, with 16/17 replicates for each treatment (Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e). We employed 25,920 mites in total for the experimental trials. The density set up fell into spider mite density in nature which ranges from 0.1 to 50 individuals/cm\u003csup\u003e2\u003c/sup\u003e (Helle and Sabelis \u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e1985\u003c/span\u003e; Geroh et al. \u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e2010\u003c/span\u003e). For each replicate, we transferred 1-day-old virgin males and females of a desired number according to treatments onto the starting leaf square and allowed them to settle for 30 minutes. We then connected all leaf squares using Parafilm bridges (4.5 cm length \u0026times; 1.5 cm width; Parafilm\u0026reg;, USA). We allowed mites to disperse freely for 72 hours, after which time, removed all bridges and counted the number of adults on each leaf square. We then removed all adults and counted the number of eggs on each leaf square. All leaf squares with eggs were individually transferred onto wet cotton in a Petri dish, and the eggs were reared on their original leaf squares until adults to record offspring egg-to-adult survival.\u003c/p\u003e\u003cp\u003eDispersal probability was defined as the percentage of mites that dispersed out of the starting leaf square. We numbered the leaf squares progressively from the starting leaf square to estimate the dispersal distance and regarded the starting leaf square as zero distance. The mean dispersal distance of a replicate was calculated by averaging the dispersal distance of all individuals in the replicate, and the total egg production per replicate was determined by counting eggs on all leaf squares. Mean egg distance was calculated for each replicate through averaging distances of all individual eggs. Offspring survival was estimated as the proportion of eggs developing to adulthood.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eA factorial design showing nine treatments of three sex ratios and population densities\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"4\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u003cp\u003eSex ratio\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003ePopulation density (no. of individuals)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003eTreatment\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u003cp\u003eReplicate (n)\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e1♀:3♂\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e20\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e5♀:15♂\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e16\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e80\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e20♀:60♂\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e17\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e160\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e40♀:120♂\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e17\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e1♀:1♂\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e20\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e10♀:10♂\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e16\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e80\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e40♀:40♂\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e17\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e160\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e80♀:80♂\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e16\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e3♀:1♂\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e20\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e15♀:5♂\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e16\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e80\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e60♀:20♂\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e16\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e160\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e120♀:40♂\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e17\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003cdiv id=\"Sec6\" class=\"Section2\"\u003e\u003ch2\u003eStatistical analysis\u003c/h2\u003e\u003cp\u003eWe analyzed data using SAS v.9.4 with a reject level set at α\u0026thinsp;=\u0026thinsp;0.05. We applied a generalized linear model to analyse the effects of fixed factors of sex, sex ratio and population density, and their interactions on five response variables (i.e., dispersal probability, dispersal distance, number of eggs, distance of eggs and offspring survival rate) (GLMMIX procedure). Dispersal probability and offspring survival rate were modeled with a binomial distribution and a logit-link function, while the dispersal distance, number of eggs, and distance of eggs were modeled with a gamma distribution and a log-link function. For offspring survival rate, the number of eggs, and distance of eggs, sex was not included as a fixed factor. Post-hoc pairwise comparisons of least-squares means were conducted using the Tukey-Kramer method.\u003c/p\u003e\u003c/div\u003e"},{"header":"Results","content":"\u003cdiv id=\"Sec8\" class=\"Section2\"\u003e\u003ch2\u003eDispersal probability and dispersal distance\u003c/h2\u003e\u003cp\u003eDispersal probability was significantly affected by sex and population density, but not by sex ratio alone (Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e; Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e). Female \u003cem\u003eT. urticae\u003c/em\u003e had a significantly higher dispersal probability than males; however, sex-biased dispersal depended on population density (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003ea and \u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003ee), i.e., male and female had similar dispersal probabilities at a lower population density (i.e., 20), but significantly more females dispersed than males at higher population densities (i.e., 80 and 160). Dispersal probability increased significantly with population density, and the significant interaction between sex ratio and population density resulted in a significantly greater dispersal at a higher density of 180 with a sex ratio of 3♀:1♂ (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003ec and \u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003ef). No significant interaction was found between sex and sex ratio, or between sex, sex ratio, and population density (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003ed and \u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003eg).\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab2\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eEffect of sex, sex ratio (SR), population density (PD) and their interactions on dispersal probability and distance in \u003cem\u003eT. urticae\u003c/em\u003e\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"4\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u003cp\u003eEffect\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003eDF\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003eF\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u003cp\u003eP\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003ctr\u003e\u003cth align=\"left\" colspan=\"4\" nameend=\"c4\" namest=\"c1\"\u003e\u003cp\u003e\u003cem\u003eDispersal probability\u003c/em\u003e\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eSex\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e1, 278\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e71.07\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e\u0026lt;\u0026thinsp;0.0001\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eSR\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e2, 278\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e1.18\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e0.3097\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003ePD\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e2, 278\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e48.75\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e\u0026lt;\u0026thinsp;0.0001\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eSex*SR\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e2, 278\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e2.55\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e0.0802\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eSex*PD\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e2, 278\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e9.34\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e0.0001\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eSR*PD\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e4, 278\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e10.38\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e\u0026lt;\u0026thinsp;0.0001\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eSex*SR*PD\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e4, 278\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e2.24\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e0.0647\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colspan=\"4\" nameend=\"c4\" namest=\"c1\"\u003e\u003cp\u003e\u003cb\u003eDispersal distance\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eSex\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e1, 272\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e19.04\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e\u0026lt;\u0026thinsp;.0001\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eSR\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e2, 272\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e0.77\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e0.4625\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003ePD\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e2, 272\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e20.29\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e\u0026lt;\u0026thinsp;0.0001\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eSex*SR\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e2, 272\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e0.51\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e0.6025\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eSex*PD\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e2, 272\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e6.04\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e0.0027\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eSR*PD\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e4, 272\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e1.29\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e0.2748\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eSex*SR*PD\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e4, 272\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e0.39\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e0.8142\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003cp\u003eDispersal distance was significantly affected by sex and population density, but not by sex ratio alone (Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e; Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e). Females dispersed a significantly longer distance than males, and dispersal distance increased significantly with population density (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ea and \u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ec). However, sex-biased dispersal depended on population density (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ee), i.e., male and female had similar dispersal distance at low and medium population densities (i.e., 20 and 80), but females dispersed significantly longer than males at high population density (i.e., 160). No significant interaction was found between sex and sex ratio, between sex ratio and population density, or between sex, sex ratio, and population density (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ed, \u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ef and \u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003eg).\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003e\u003cem\u003eEffect of sex ratio, population density and their interactions on total number of eggs, egg distance, and offspring survival rate\u003c/em\u003e\u003c/p\u003e\u003cp\u003eThe number of eggs laid was significantly higher at a female-biased sex ratio and increased significantly with increasing population density (Table\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e; Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003e). Eggs were deposited significantly farther at higher population densities of 80 and 160 than at the lower one, but neither sex ratio nor the interaction between population density and sex ratio had significant impact on egg deposition distance (Table\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e; Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003e). A female-biased sex ratio and increasing population density significantly decreased offspring survival rate (Table\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e; Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003e).\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab3\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 3\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eEffect of sex ratio (SR), population density (PD) and their interactions on total number of eggs laid, egg deposition distance, and offspring survival rate in \u003cem\u003eT. urticae\u003c/em\u003e\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"4\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u003cp\u003eEffect\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003eDF\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003eF\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u003cp\u003eP\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003ctr\u003e\u003cth align=\"left\" colspan=\"4\" nameend=\"c4\" namest=\"c1\"\u003e\u003cp\u003e\u003cem\u003eNo. eggs\u003c/em\u003e\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eSR\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e2, 139\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e50.80\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e\u0026lt;\u0026thinsp;0.0001\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003ePD\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e2, 139\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e152.67\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e\u0026lt;\u0026thinsp;0.0001\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eSR*PD\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e4, 139\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e0.33\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e0.8576\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colspan=\"4\" nameend=\"c4\" namest=\"c1\"\u003e\u003cp\u003e\u003cb\u003eEgg distance\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eSR\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e2, 134\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e0.74\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e0.4814\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003ePD\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e2, 134\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e9.55\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e0.0001\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eSR*PD\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e4, 134\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e0.8\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e0.5249\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colspan=\"4\" nameend=\"c4\" namest=\"c1\"\u003e\u003cp\u003e\u003cb\u003eOffspring survival (%)\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eSR\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e2, 139\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e19.17\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e\u0026lt;\u0026thinsp;0.0001\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003ePD\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e2, 139\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e142.67\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e\u0026lt;\u0026thinsp;0.0001\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eSR*PD\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e4, 139\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e11.47\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e\u0026lt;\u0026thinsp;0.0001\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003c/div\u003e"},{"header":"Discussion","content":"\u003cdiv id=\"Sec10\" class=\"Section2\"\u003e\u003ch2\u003eSex-biased dispersal\u003c/h2\u003e\u003cp\u003eWe show that dispersal probability and distance in \u003cem\u003eT. urticae\u003c/em\u003e were significantly influenced by sex and population density, but not by sex ratio. Females dispersed more frequently and farther than males, although the strength of this bias varied with density (Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e, Figs.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e and \u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e). This overall tendency toward female-biased dispersal was consistent with previous studies on spider mites (Krainacker and Carey \u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e1990a\u003c/span\u003e; Clotuche et al. \u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e2013\u003c/span\u003e). Such female-biased dispersal in \u003cem\u003eT. urticae\u003c/em\u003e is likely facilitated by differences in physiology and life-history traits that mediate sex-specific costs and benefits of dispersal (Gros et al. \u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e2008\u003c/span\u003e; Li and Kokko \u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e2019\u003c/span\u003e). \u003cem\u003eTetranychus\u003c/em\u003e females are much larger than males, with longer legs promoting movement and more energy reserves to withstand starvation and dehydration during dispersal (Li and Zhang \u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e2018\u003c/span\u003e; Ristyadi et al. \u003cspan citationid=\"CR52\" class=\"CitationRef\"\u003e2022\u003c/span\u003e); therefore, dispersal is likely to be less costly to females. Furthermore, spider mites are \u003cem\u003er\u003c/em\u003e-selected species with high reproductive output and rapid population growth rate, and females frequently experience severe intrasexual competition. Indeed, our results show that the number of females in a population directly determined the number of eggs produced, creating variations in offspring survival rates (Figs.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003e and \u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003e). Consequently, the benefits of dispersal may be greater for females, as leaving crowded patches can reduce competition and increase offspring fitness by finding new oviposition sites.\u003c/p\u003e\u003cp\u003eMale-male competition and mate finding typically drive male-biased dispersal in many species (Hovestadt et al. \u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e2014\u003c/span\u003e; Li and Kokko \u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e2019\u003c/span\u003e); however, spider mite males may experience weaker selection pressure to disperse for mates outside their natal habitats. In \u003cem\u003eTetranychus\u003c/em\u003e mites, males typically guard quiescent deutonymphs and mate immediately upon female emergence (Jiao and Zhang \u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e2025\u003c/span\u003e). They have high reproductive capacity that is sufficient to inseminate all females within a natal population (Krainacker and Carey \u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e1990b\u003c/span\u003e). For example, a 1-d-old male could inseminate up to 15 females (Krainacker and Carey \u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e1989\u003c/span\u003e), and mate with five females per day without compromising insemination quality (Krainacker and Carey \u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e1990b\u003c/span\u003e). Most importantly, only the female's first mating is biologically effective (Helle \u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e1967\u003c/span\u003e; Potter and Wrensch \u003cspan citationid=\"CR49\" class=\"CitationRef\"\u003e1978\u003c/span\u003e; Oku \u003cspan citationid=\"CR44\" class=\"CitationRef\"\u003e2008\u003c/span\u003e; Rodrigues et al. \u003cspan citationid=\"CR53\" class=\"CitationRef\"\u003e2020\u003c/span\u003e; Morita et al. \u003cspan citationid=\"CR40\" class=\"CitationRef\"\u003e2021\u003c/span\u003e). These life-history traits reduce the likelihood of males encountering receptive mates in novel habitats and thus gaining less benefits from dispersal. Nevertheless, a substantial proportion of males also dispersed and spread out over a considerable distance (Figs.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e and \u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e), indicating that both sexes contribute to population spread. Male mites may still possess excess reproductive capability even under a female-biased sex ratio of 3♀:1♂ as set up in this study, which may motivate them to disperse and search for mates even though the probability of success is low.\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec11\" class=\"Section2\"\u003e\u003ch2\u003eEffects of population density\u003c/h2\u003e\u003cp\u003eThe dispersal probability and distance of either sex increased significantly with population density (Figs.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003ec, \u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003ee, \u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ec and \u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ee) indicating that population density was a strong driver of dispersal in both sexes. These may be due to the increase of intra-sexual competition or inter-sexual conflict with increasing population density (Weerawansha et al. \u003cspan citationid=\"CR58\" class=\"CitationRef\"\u003e2020\u003c/span\u003e, \u003cspan citationid=\"CR59\" class=\"CitationRef\"\u003e2022\u003c/span\u003e, \u003cspan citationid=\"CR60\" class=\"CitationRef\"\u003e2023\u003c/span\u003e). At a low population density, females and males dispersed at similar rates and distances, while at high densities females dispersed more frequently and farther than males (Figs.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003ee and \u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ee), suggesting that increasing density amplifies sex-specific responses to competition, i.e., although both sexes might attempt to disperse from the crowded habitats, females faced significantly greater competitive pressure than males in dense populations. We show that at a low population density of 20 individuals, offspring survival rate was the highest but similar across three sex ratios (Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003ec), suggesting limited offspring competition at this environmental condition. In contrast, the survival rate significantly decreased with increasing population density, and the magnitude of reduction was greater at the female-biased sex ratio (Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003ec), indicating severe offspring competition at high density with a female-biased sex ratio. Therefore, we suggest that increasing density promotes dispersal in both sexes, whereas females respond more strongly because of their greater sensitivity to intense intrasexual competition.\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec12\" class=\"Section2\"\u003e\u003ch2\u003eEffects of sex ratio\u003c/h2\u003e\u003cp\u003eIn contrast to the effect of population density, sex ratio did not significantly affect dispersal probability or distance, and the interaction between sex and sex ratio was not significant (Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e; Figs.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003ea, \u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003eb, \u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003ed, \u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ea, \u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003eb and \u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ed), indicating that dispersal in \u003cem\u003eT. urticae\u003c/em\u003e was independent of population sex ratio. Theoretical models and empirical studies suggest that individuals should adjust their dispersal behavior in response to the strength of intra- and inter-sexual competition (De Meester and Bonte \u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e2010\u003c/span\u003e; Nelson and Greeff \u003cspan citationid=\"CR41\" class=\"CitationRef\"\u003e2011\u003c/span\u003e; Hovestadt et al. \u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e2014\u003c/span\u003e; Lee et al. \u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e2021\u003c/span\u003e; Cimiotti et al. \u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e2024\u003c/span\u003e). As shown in Figs.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003ea and \u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003ea, when population sex ratio shifted towards female bias, females produced significantly more eggs, which led to a significant decrease in offspring survival rate. Females are thus subject to more intense intrasexual competition and expected to have higher dispersal probability and longer dispersal distance in female-biased populations.\u003c/p\u003e\u003cp\u003eHowever, our results show that dispersal probability and distance were similar across female-biased (3♀:1♂), equal (1♀:1♂), and male-biased (1♀:3♂) sex ratios, suggesting that sex ratio may affect dispersal pattern through multiple mechanisms. In our experimental setup, we kept population density constant with varying sex ratios, which means that populations with lower female numbers had proportionally more males. In many species, male harassment is a strong driver of female dispersal (Odendaal et al. \u003cspan citationid=\"CR42\" class=\"CitationRef\"\u003e1989\u003c/span\u003e; Trochet et al. \u003cspan citationid=\"CR57\" class=\"CitationRef\"\u003e2013\u003c/span\u003e; Lee et al. \u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e2021\u003c/span\u003e; Cimiotti et al. \u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e2024\u003c/span\u003e). For example, male harassment leads to female emigration at a high male density in a butterfly \u003cem\u003eProclossiana eunomiu\u003c/em\u003e (Baguette et al. \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e1998\u003c/span\u003e). In spider mites, male harassment may result in fewer fecundity, less female-biased offspring, and shortened longevity (Oku \u003cspan citationid=\"CR45\" class=\"CitationRef\"\u003e2010\u003c/span\u003e; Macke et al. \u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e2012\u003c/span\u003e; Rodrigues et al. \u003cspan citationid=\"CR53\" class=\"CitationRef\"\u003e2020\u003c/span\u003e; Li and Zhang \u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e2021\u003c/span\u003e). Females in populations with equal or male-biased sex ratios may disperse to avoid male harassment. Our results thus suggest that both female intrasexual competition in female-biased populations and male harassment in male-biased populations occurred simultaneously, resulting in consistently higher female dispersal at all sex ratio levels but masking clear sex ratio effects.\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec13\" class=\"Section2\"\u003e\u003ch2\u003eFitness consequences of dispersal\u003c/h2\u003e\u003cp\u003eDispersal could influence reproductive fitness and population dynamics in several ways, and its consequences in \u003cem\u003eT. urticae\u003c/em\u003e are closely tied to the effects of density and sex ratio observed in our study. First, greater dispersal probability and longer dispersal distance allowed individuals to move farther from their natal habitat, and thereby reducing local competition for resources among conspecifics and their offspring. For example, in \u003cem\u003eT. ludeni\u003c/em\u003e, females producing more eggs have higher dispersal probability and longer dispersal distance, which reduces offspring competition and increases their fitness (Zhou et al. \u003cspan citationid=\"CR63\" class=\"CitationRef\"\u003e2024\u003c/span\u003e). Similarly, in this study, the higher dispersal probability and longer dispersal distance of females spread eggs over longer distances, which may promote pest outbreak and range expansion. However, despite wider egg distribution, increased egg production from more females still resulted in lower offspring survival (Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003e), indicating that dispersal cannot fully offset the intense female intrasexual competition. Second, male dispersal, although less extensive, may further affect population dynamics by accompanying females into new patches and affecting the distribution of previously dispersed females, shaping the dispersal outcomes and their fitness consequences. Male-female interactions may also reduce female fecundity and longevity in new habitats (Oku \u003cspan citationid=\"CR45\" class=\"CitationRef\"\u003e2010\u003c/span\u003e; Macke et al. \u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e2012\u003c/span\u003e; Rodrigues et al. \u003cspan citationid=\"CR53\" class=\"CitationRef\"\u003e2020\u003c/span\u003e; Li and Zhang \u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e2021\u003c/span\u003e), which warrants further investigation.\u003c/p\u003e\u003c/div\u003e"},{"header":"Conclusion","content":"\u003cp\u003eThis study demonstrates that dispersal in \u003cem\u003eT. urticae\u003c/em\u003e is strongly density-dependent and generally female-biased, but independent of sex ratio. Both sexes dispersed more frequently and farther at higher densities, but females exhibited a stronger response, reflecting the higher costs of competition and greater benefits of dispersal. Female intrasexual competition in female-biased populations and male harassment in male-biased populations likely acted simultaneously, resulting in consistently higher female-biased dispersal at all sex ratio levels. By spreading eggs over wider areas, female dispersal in particular may facilitate colonization, outbreaks, and range expansion. Male dispersal, although less extensive, may reduce fecundity and influence the distribution of females in new habitats. This study highlights the ecological importance of sex-specific dispersal in regulating spider mite population dynamics.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003ch2\u003eCompeting Interests\u003c/h2\u003e\u003cp\u003eThe authors declare no conflicts of interest.\u003c/p\u003e\u003c/p\u003e\u003ch2\u003eFunding\u003c/h2\u003e\u003cp\u003eThe work was supported by the Key Scientific Research Programs of Universities in Anhui Province (2024AH051125; 2024AH051080), the Provincial Graduate Education Quality Engineering Project of Anhui Province (2024yjshhsfkc040), and the Key Laboratory of Biodiversity Conservation and Characteristic Resource Utilization in Southwest Anhui (Wxn202405), and the Engineering Technology Research Center for Aquatic Organism Conservation and Water Ecosystem Restoration in University of Anhui Province (Ss202404).\u003c/p\u003e\u003ch2\u003eAuthor Contribution\u003c/h2\u003e\u003cp\u003eP.Z., X.Z.H. and C.C. conceived and designed the study. P.Z., Y.J.Z., Z.H.W., Y.L.F., J.L. and Z.Y.Z. performed the experiment. P.Z., X.Z.H. and C.C. analysed the data. All authors contributed to manuscript preparation.\u003c/p\u003e\u003ch2\u003eAcknowledgement\u003c/h2\u003e\u003cp\u003eWe thank Xue Zhao for her assistance with the experiment.\u003c/p\u003e\u003ch2\u003eData Availability\u003c/h2\u003e\u003cp\u003eThe datasets generated and analysed during the current study are available from the corresponding author on reasonable request.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eAzand\u0026eacute;m\u0026egrave;-Hounmalon GY, Fellous S, Kreiter S, Fiaboe KK, Subramanian S, Kungu M, Martin T (2014) Dispersal behavior of \u003cem\u003eTetranychus evansi\u003c/em\u003e and \u003cem\u003eT. urticae\u003c/em\u003e on tomato at several spatial scales and densities: implications for integrated pest management. PLoS ONE 9:e95071. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1371/journal.pone.0095071\u003c/span\u003e\u003cspan address=\"10.1371/journal.pone.0095071\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eBaguette M, Vansteenwegen C, Convi I, N\u0026egrave;ve G (1998) Sex-biased density-dependent migration in a metapopulation of the butterfly \u003cem\u003eProclossiana eunomia\u003c/em\u003e. Acta Oecol 19:17\u0026ndash;24. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/S1146-609X(98)80004-0\u003c/span\u003e\u003cspan address=\"10.1016/S1146-609X(98)80004-0\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eBaines CB, Ferzoco IM, McCauley SJ (2017) Sex-biased dispersal is independent of sex ratio in a semiaquatic insect. Behav Ecol Sociobiol 71:119. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1007/s00265-017-2348-7\u003c/span\u003e\u003cspan address=\"10.1007/s00265-017-2348-7\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eBaines CB, Ferzoco IMC, McCauley SJ (2019) Phenotype-by-environment interactions influence dispersal. J Anim Ecol 88:1263\u0026ndash;1274. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1111/1365-2656.13008\u003c/span\u003e\u003cspan address=\"10.1111/1365-2656.13008\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eBitume EV, Bonte D, Ronce O, Bach F, Flaven E, Olivieri I, Nieberding CM (2013) Density and genetic relatedness increase dispersal distance in a subsocial organism. Ecol Lett 16:430\u0026ndash;437. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1111/ele.12057\u003c/span\u003e\u003cspan address=\"10.1111/ele.12057\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eBonte D, Van Dyck H, Bullock JM, Coulon A, Delgado M, Gibbs M, Lehouck V, Matthysen E, Mustin K, Saastamoinen M, Schtickzelle N, Stevens VM, Vandewoestijne S, Baguette M, Barton K, Benton TG, Chaput-Bardy A, Clobert J, Dytham C, Hovestadt T, Meier CM, Palmer SC, Turlure C, Travis JM (2012) Costs of dispersal. Biol Rev Camb Philos Soc 87:290\u0026ndash;312. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1111/j.1469-185X.2011.00201.x\u003c/span\u003e\u003cspan address=\"10.1111/j.1469-185X.2011.00201.x\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eChaput-Bardy A, Gregoire A, Baguette M, Pagano A, Secondi J (2010) Condition and phenotype-dependent dispersal in a damselfly, \u003cem\u003eCalopteryx splendens\u003c/em\u003e. PLoS ONE 5(5):e10694. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1371/journal.pone.0010694\u003c/span\u003e\u003cspan address=\"10.1371/journal.pone.0010694\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eCimiotti DV, Eberhart-Hertel L, Audevard A, Salas PJG, Gelinaud G, G\u0026uuml;nther K, Rocha A, Schulz R, van der Winden J, Schmaljohann H, K\u0026uuml;pper C (2024) Dispersal in kentish plovers \u003cem\u003eCharadrius alexandrinus\u003c/em\u003e: Adult females perform furthest movements. J Ornithol 165:301\u0026ndash;314. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1007/s10336-023-02120-5\u003c/span\u003e\u003cspan address=\"10.1007/s10336-023-02120-5\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eClobert J, Le Galliard JF, Cote J, Meylan S, Massot M (2009) Informed dispersal, heterogeneity in animal dispersal syndromes and the dynamics of spatially structured populations. Ecol Lett 12:197\u0026ndash;209. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1111/j.1461-0248.2008.01267.x\u003c/span\u003e\u003cspan address=\"10.1111/j.1461-0248.2008.01267.x\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eClotuche G, Navajas M, Mailleux AC, Hance T (2013) Reaching the ball or missing the flight? collective dispersal in the two-spotted spider mite \u003cem\u003eTetranychus urticae\u003c/em\u003e. PLoS ONE 8(10):e77573. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1371/journal.pone.0077573\u003c/span\u003e\u003cspan address=\"10.1371/journal.pone.0077573\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eDahirel M, Masier S, Renault D, Bonte D (2019) The distinct phenotypic signatures of dispersal and stress in an arthropod model: from physiology to life history. J Exp Biol 222(16):jeb203596. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1242/jeb.203596\u003c/span\u003e\u003cspan address=\"10.1242/jeb.203596\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eDahirel M, Vardakis M, Ansart A, Madec L (2016) Density-dependence across dispersal stages in a hermaphrodite land snail: insights from discrete choice models. Oecologia 181:1117\u0026ndash;1128. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1007/s00442-016-3636-z\u003c/span\u003e\u003cspan address=\"10.1007/s00442-016-3636-z\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eDe Meester N, Bonte D (2010) Information use and density-dependent emigration in an agrobiont spider. Behav Ecol 21:992\u0026ndash;998. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1093/beheco/arq088\u003c/span\u003e\u003cspan address=\"10.1093/beheco/arq088\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eFranckowiak RP, Ridgway MS, Wilson CC (2025) Natal philopatry and sex-biased dispersal in a nest defence mating system. Anim Behav 225:123211. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.anbehav.2025.123211\u003c/span\u003e\u003cspan address=\"10.1016/j.anbehav.2025.123211\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eGeroh M, Gulati R, Sharma S, Kaushik H, Aneja D (2010) Effect of abiotic stresses on population build up of \u003cem\u003eTetranychus urticae\u003c/em\u003e Koch and its predator, \u003cem\u003eStethorus punctillum\u003c/em\u003e weise on okra. Ann Plant Prot Sci 18:108\u0026ndash;113. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://www.cabidigitallibrary.org/doi/full/\u003c/span\u003e\u003cspan address=\"https://www.cabidigitallibrary.org/doi/full/\" targettype=\"URL\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.5555/20103164554\u003c/span\u003e\u003cspan address=\"10.5555/20103164554\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eGros A, Hovestadt T, Poethke HJ (2008) Evolution of sex-biased dispersal: the role of sex-specific dispersal costs, demographic stochasticity, and inbreeding. Ecol Model 219:226\u0026ndash;233. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.ecolmodel.2008.08.014\u003c/span\u003e\u003cspan address=\"10.1016/j.ecolmodel.2008.08.014\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eGros A, Poethke HJ, Hovestadt T (2009) Sex-specific spatio-temporal variability in reproductive success promotes the evolution of sex-biased dispersal. Theor Popul Biol 76:13\u0026ndash;18. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.tpb.2009.03.002\u003c/span\u003e\u003cspan address=\"10.1016/j.tpb.2009.03.002\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eHelle W (1967) Fertilization in the two-spotted spider mite (\u003cem\u003eTetranychus urticae\u003c/em\u003e: Acari). Entomol Exp Appl 10:103\u0026ndash;110. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1111/j.1570-7458.1967.tb00049.x\u003c/span\u003e\u003cspan address=\"10.1111/j.1570-7458.1967.tb00049.x\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eHelle W, Sabelis MW (1985) Spider mites: Their biology, natural enemies and control. Amsterdam, Netherlands, Elsevier\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eHewison AJM, Gaillard JM, Morellet N, Cagnacci F, Debeffe L, Cargnelutti B, Gehr B, Kroschel M, Heurich M, Coulon A, Kjellander P, Borger L, Focardi S (2021) Sex differences in condition dependence of natal dispersal in a large herbivore: dispersal propensity and distance are decoupled. Proc R Soc B 288:20202947. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1098/rspb.2020.2947\u003c/span\u003e\u003cspan address=\"10.1098/rspb.2020.2947\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eHovestadt T, Mitesser O, Poethke H-J (2014) Gender-specific emigration decisions sensitive to local male and female density. Am Nat 184:38\u0026ndash;51. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1086/676524\u003c/span\u003e\u003cspan address=\"10.1086/676524\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eJiao A, Zhang Z-Q (2025) Precopulatory guarding of old and young quiescent deutonymph females by adult male \u003cem\u003eTetranychus evansi\u003c/em\u003e (Acari: Tetranychidae). Syst Appl Acarol 30:835\u0026ndash;838. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.11158/saa.30.5.1\u003c/span\u003e\u003cspan address=\"10.11158/saa.30.5.1\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eJohnstone RA, Cant MA, Field J (2012) Sex-biased dispersal, haplodiploidy and the evolution of helping in social insects. Proc R Soc B 279:787\u0026ndash;793. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1098/rspb.2011.1257\u003c/span\u003e\u003cspan address=\"10.1098/rspb.2011.1257\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eKrainacker D, Carey J (1989) Reproductive limits and heterogeneity of male twospotted spider mites. Entomol Exp Appl 50:209\u0026ndash;214. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1111/j.1570-7458.1989.tb01194.x\u003c/span\u003e\u003cspan address=\"10.1111/j.1570-7458.1989.tb01194.x\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eKrainacker DA, Carey JR (1990a) Ambulatory dispersal and life history response to food deprivation in twospotted spider mites. Entomol Exp Appl 56:139\u0026ndash;144. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1111/j.1570-7458.1990.tb01391.x\u003c/span\u003e\u003cspan address=\"10.1111/j.1570-7458.1990.tb01391.x\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eKrainacker DA, Carey JR (1990b) Male demographic constraints to extreme sex ratio in the twospotted spider mite. Oecologia 82:417\u0026ndash;423. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1007/BF00317492\u003c/span\u003e\u003cspan address=\"10.1007/BF00317492\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eKrainacker DA, Carey JR (1991) Sex ratio in a wild population of twospotted spider mites. Ecography 14:97\u0026ndash;103. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1111/j.1600-0587.1991.tb00639.x\u003c/span\u003e\u003cspan address=\"10.1111/j.1600-0587.1991.tb00639.x\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eLaska A, Rector BG, Przychodzka A, Majer A, Zalewska K, Kuczynski L, Skoracka A (2023) Do mites eat and run? A systematic review of feeding and dispersal strategies. Zool J Linn Soc 198:462\u0026ndash;475. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1093/zoolinnean/zlac094\u003c/span\u003e\u003cspan address=\"10.1093/zoolinnean/zlac094\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eLee MR, Udina CS, Hansson LA (2021) Fear of sex: sexual conflict exposed as avoidance in a parthenogenetic invertebrate. Behav Ecol Sociobiol 75:115. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1007/s00265-021-03054-9\u003c/span\u003e\u003cspan address=\"10.1007/s00265-021-03054-9\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eLi G-Y, Zhang Z-Q (2018) Does size matter? Fecundity and longevity of spider mites (\u003cem\u003eTetranychus urticae\u003c/em\u003e) in relation to mating and food availability. Syst Appl Acarol 23:1796\u0026ndash;1808. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.11158/saa.23.9.6\u003c/span\u003e\u003cspan address=\"10.11158/saa.23.9.6\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eLi G-Y, Zhang Z-Q (2021) The costs of social interaction on survival and reproduction of arrhenotokous spider mite \u003cem\u003eTetranychus urticae\u003c/em\u003e. Entomol Gen 41:49\u0026ndash;57. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1127/entomologia/2020/0911\u003c/span\u003e\u003cspan address=\"10.1127/entomologia/2020/0911\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eLi J, Margolies DC (1993) Effects of mite age, mite density, and host quality on aerial dispersal behavior in the twospotted spider mite. Entomol Exp Appl 68:79\u0026ndash;86. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1111/j.1570-7458.1993.tb01691.x\u003c/span\u003e\u003cspan address=\"10.1111/j.1570-7458.1993.tb01691.x\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eLi XY, Kokko H (2019) Sex-biased dispersal: a review of the theory. Biol Rev 94:721\u0026ndash;736. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1111/brv.12475\u003c/span\u003e\u003cspan address=\"10.1111/brv.12475\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eMacke E, Magalhaes S, Do-Thi Khanh H, Frantz A, Facon B, Olivieri I (2012) Mating modifies female life history in a haplodiploid spider mite. Am Nat 179:147\u0026ndash;162. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1086/665002\u003c/span\u003e\u003cspan address=\"10.1086/665002\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eMatthysen E (2012) Multicausality of dispersal: a review. In: Clobert J, Baguette M, Benton TG, Bullock JM (eds) Dispersal ecology and evolution. Oxford University Press, London, pp 3\u0026ndash;18\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eMigeon A, Dorkeld F (2025) Spider mites web: a comprehensive database for the tetranychidae. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttp://www1.Montpellier.Inra.Fr/cbgp/spmweb\u003c/span\u003e\u003cspan address=\"http://www1.Montpellier.Inra.Fr/cbgp/spmweb\" targettype=\"URL\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e. Accessed 3 August 2025\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eMishra A, Tung S, Sruti VRS, Srivathsa S, Dey S (2020) Mate-finding dispersal reduces local mate limitation and sex bias in dispersal. J Anim Ecol 89:2089\u0026ndash;2098. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1111/1365-2656.13278\u003c/span\u003e\u003cspan address=\"10.1111/1365-2656.13278\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eMishra A, Tung S, Sruti VS, Sadiq MA, Srivathsa S, Dey S (2018) Pre-dispersal context and presence of opposite sex modulate density dependence and sex bias of dispersal. Oikos 127:1596\u0026ndash;1604. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1111/oik.04902\u003c/span\u003e\u003cspan address=\"10.1111/oik.04902\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eMitchell R (1973) Growth and population dynamics of a spider mite (\u003cem\u003eTetranychus urticae\u003c/em\u003e K., Acarina: Tetranychidae). Ecology 54:1349\u0026ndash;1355. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.2307/1934198\u003c/span\u003e\u003cspan address=\"10.2307/1934198\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eMorita A, Ullah MS, Sugawara R, Gotoh T (2021) Effects of male and female age on mating success in \u003cem\u003eTetranychus urticae\u003c/em\u003e Koch (Acari: Tetranychidae). Syst Appl Acarol 26:1280\u0026ndash;1292. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.11158/saa.26.7.8\u003c/span\u003e\u003cspan address=\"10.11158/saa.26.7.8\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eNelson RM, Greeff JM (2011) Sex ratio dependent dispersal when sex ratios vary between patches. J Theor Biol 290:81\u0026ndash;87. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.jtbi.2011.08.030\u003c/span\u003e\u003cspan address=\"10.1016/j.jtbi.2011.08.030\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eOdendaal FJ, Turchin P, Stermitz FR (1989) Influence of host-plant density and male harassment on the distribution of female \u003cem\u003eEuphydryas anicia\u003c/em\u003e (nymphalidae). Oecologia 78:283\u0026ndash;288. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1007/BF00377167\u003c/span\u003e\u003cspan address=\"10.1007/BF00377167\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eOhzora Y, Yano S (2011) Voluntary falling in spider mites in response to different ecological conditions at landing points. J Insect Behav 24:274\u0026ndash;281. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1007/s10905-010-9253-5\u003c/span\u003e\u003cspan address=\"10.1007/s10905-010-9253-5\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eOku K (2008) Is only the first mating effective for females in the kanzawa spider mite, \u003cem\u003eTetranychus kanzawai\u003c/em\u003e (Acari: Tetranychidae)? Exp Appl Acarol 45:53\u0026ndash;57. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1007/s10493-008-9157-7\u003c/span\u003e\u003cspan address=\"10.1007/s10493-008-9157-7\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eOku K (2010) Males of the two-spotted spider mite attempt to copulate with mated females: Effects of double mating on fitness of either sex. Exp Appl Acarol 50:107\u0026ndash;113. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1007/s10493-009-9306-7\u003c/span\u003e\u003cspan address=\"10.1007/s10493-009-9306-7\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003ePerrin N, Mazalov V (2000) Local competition, inbreeding, and the evolution of sex-biased dispersal. Am Nat 155:116\u0026ndash;127. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1086/303296\u003c/span\u003e\u003cspan address=\"10.1086/303296\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003ePlazio E, Margol T, Nowicki P (2020) Intersexual differences in density-dependent dispersal and their evolutionary drivers. J Evol Biol 33:1495\u0026ndash;1506. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1111/jeb.13688\u003c/span\u003e\u003cspan address=\"10.1111/jeb.13688\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003ePotter DA (1978) Functional sex ratio in the carmine spider mite. Ann Entomol Soc Am 71:218\u0026ndash;222. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1093/aesa/71.2.218\u003c/span\u003e\u003cspan address=\"10.1093/aesa/71.2.218\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003ePotter DA, Wrensch DL (1978) Interrupted matings and the effectiveness of second inseminations in the twospotted spider mite. Ann Entomol Soc Am 71:882\u0026ndash;885. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1093/aesa/71.6.882\u003c/span\u003e\u003cspan address=\"10.1093/aesa/71.6.882\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003ePotter DA, Wrensch DL, Johnston DE (1976) Guarding, aggressive behavior, and mating success in male twospotted spider mites. Ann Entomol Soc Am 69:707\u0026ndash;711. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1093/aesa/69.4.707\u003c/span\u003e\u003cspan address=\"10.1093/aesa/69.4.707\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eRenault D (2020) A review of the phenotypic traits associated with insect dispersal polymorphism, and experimental designs for sorting out resident and disperser phenotypes. Insects 11:214. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.3390/insects11040214\u003c/span\u003e\u003cspan address=\"10.3390/insects11040214\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eRistyadi D, He XZ, Wang Q (2022) Resource allocation strategies for survival and reproduction by an invasive pest in response to intermittent fasting. Curr Zool 69:600\u0026ndash;606. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1093/cz/zoac068\u003c/span\u003e\u003cspan address=\"10.1093/cz/zoac068\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eRodrigues LR, Figueiredo ART, Van Leeuwen T, Olivieri I, Magalhaes S (2020) Costs and benefits of multiple mating in a species with first-male sperm precedence. J Anim Ecol 89:1045\u0026ndash;1054. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1111/1365-2656.13171\u003c/span\u003e\u003cspan address=\"10.1111/1365-2656.13171\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eSantini L, Fernando M, Mancini G, Di Marco M (2025) The neglected role of sex-biased dispersal in range-shift prediction under climate change. Divers Distrib 31:e13942. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1111/ddi.13942\u003c/span\u003e\u003cspan address=\"10.1111/ddi.13942\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eSantos FA, Rolim GS, Nachman GS, Andrade DJ (2020) Using mathematical models to describe aerial dispersal and silk ball formation of peanut red spider mite, \u003cem\u003eTetranychus ogmophallos\u003c/em\u003e (Acari: Tetranychidae). Exp Appl Acarol 81:85\u0026ndash;102. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1007/s10493-020-00495-1\u003c/span\u003e\u003cspan address=\"10.1007/s10493-020-00495-1\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eTrochet A, Courtois EA, Stevens VM, Baguette M, Chaine A, Schmeller DS, Clobert J, Wiens JJ (2016) Evolution of sex-biased dispersal. Q Rev Biol 91:297\u0026ndash;320. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1086/688097\u003c/span\u003e\u003cspan address=\"10.1086/688097\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eTrochet A, Legrand D, Larranaga N, Ducatez S, Calvez O, Cote J, Clobert J, Baguette M (2013) Population sex ratio and dispersal in experimental, two-patch metapopulations of butterflies. J Anim Ecol 82:946\u0026ndash;955. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1111/1365-2656.12082\u003c/span\u003e\u003cspan address=\"10.1111/1365-2656.12082\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eWeerawansha N, Wang Q, He XZ (2020) Effect of foundress population density and size on reproduction and population growth of a haplodiploid mite. Syst Appl Acarol 25:2063\u0026ndash;2076. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.11158/saa.25.11.11\u003c/span\u003e\u003cspan address=\"10.11158/saa.25.11.11\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eWeerawansha N, Wang Q, He XZ (2022) A haplodiploid mite adjusts fecundity and sex ratio in response to density changes during the reproductive period. Exp Appl Acarol 88:277\u0026ndash;288. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1007/s10493-022-00749-0\u003c/span\u003e\u003cspan address=\"10.1007/s10493-022-00749-0\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eWeerawansha N, Wang Q, He XZ (2023) Reproductive plasticity in response to the changing cluster size during the breeding period: a case study in a spider mite. Exp Appl Acarol 91:237\u0026ndash;250. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1007/s10493-023-00834-y\u003c/span\u003e\u003cspan address=\"10.1007/s10493-023-00834-y\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eYano S, Takafuji A (2002) Variation in the life history pattern of \u003cem\u003eTetranychus urticae\u003c/em\u003e (Acari: Tetranychidae) after selection for dispersal. Exp Appl Acarol 27:1\u0026ndash;10. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1023/A:1021518221031\u003c/span\u003e\u003cspan address=\"10.1023/A:1021518221031\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eZhou P, He XZ, Chen C, Wang Q (2021) Resource relocations in relation to dispersal in \u003cem\u003eTetranychus ludeni\u003c/em\u003e Zacher. Syst Appl Acarol 26:2018\u0026ndash;2026. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.11158/saa.26.11.3\u003c/span\u003e\u003cspan address=\"10.11158/saa.26.11.3\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eZhou P, He XZ, Chen C, Wang Q (2024) Age and density of mated females affect dispersal strategies in spider mite \u003cem\u003eTetranychus ludeni\u003c/em\u003e Zacher. Insects 15:387. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.3390/insects15060387\u003c/span\u003e\u003cspan address=\"10.3390/insects15060387\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eZsinka B, K\u0026ouml;v\u0026eacute;r S, Horv\u0026aacute;th M, Vili N, Szab\u0026oacute;-Csonka V, Szab\u0026oacute; K, P\u0026aacute;sztory-Kov\u0026aacute;cs S (2025) Sex-biased and density-dependent natal dispersal in a highly mobile but philopatric raptor. Ecol Evol 15:e71487. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1002/ece3.71487\u003c/span\u003e\u003cspan address=\"10.1002/ece3.71487\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":true,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"dispersal distance, dispersal probability, intrasexual competition, sex-specific dispersal, sexual conflict","lastPublishedDoi":"10.21203/rs.3.rs-7472280/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-7472280/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eDispersal is a multiple-stage process which can be affected by intrinsic phenotypes and extrinsic environmental conditions. Understanding how animals adjust dispersal strategies in response to these factors is essential for predicting population dynamics and providing knowledge for population management. \u003cem\u003eTetranychus urticae\u003c/em\u003e Koch (Acari: Tetranychidae) is a notorious invasive pest of global concern, damaging numerous economically important crops. Here, we examined the effect of sex, population density, and sex ratio on dispersal probability and distance in \u003cem\u003eT. urticae\u003c/em\u003e. We set up a factorial design with three densities and three sex ratios generating nine treatments. Our results show that dispersal was generally female-biased, and dispersal probability and distance increased with population density in both sexes, but the increase was significantly stronger in females. In contrast, sex ratio and interaction between sex and sex ratio had no significant effects on dispersal probability and distance. Females that dispersed farther laid eggs over longer distances. Females at female-biased sex ratios and dense populations produced more eggs but resulted in lower offspring survival rates, indicating severe intrasexual competition. We suggest that sexual dimorphism in body size, along with the relatively high benefits and low costs of female dispersal compared to males, may lead to female-biased dispersal in spider mites. Multiple mechanisms including female intrasexual competition and male harassment to females may account for the observed dispersal patterns in relation to population density and sex ratio. Female intrasexual competition and male harassment may drive female dispersal, resulting in wider egg distribution across habitats and potentially facilitating pest population outbreaks and range expansion.\u003c/p\u003e","manuscriptTitle":"Sex-biased dispersal in Tetranychus urticae mediated by population density but independent of sex ratio","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-09-15 18:52:14","doi":"10.21203/rs.3.rs-7472280/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"214656d7-aafd-4325-8030-649b54a55a9f","owner":[],"postedDate":"September 15th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2025-12-26T22:08:29+00:00","versionOfRecord":[],"versionCreatedAt":"2025-09-15 18:52:14","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-7472280","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-7472280","identity":"rs-7472280","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}