{"paper_id":"1240485d-a5bb-4b9d-aa26-84fa3364f2a3","body_text":"Biology and Determination of Larval Instars of Plutella xylostella(Linnaeus, 1758) (Lepidoptera: Plutellidae) Under High-Altitude Mountain Laboratory Conditions in the Colombian Andes | 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 Biology and Determination of Larval Instars of Plutella xylostella (Linnaeus, 1758) (Lepidoptera: Plutellidae) Under High-Altitude Mountain Laboratory Conditions in the Colombian Andes Humberto Giraldo-Vanegas This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-9534424/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 The diamondback moth, Plutella xylostella (Linnaeus, 1758) (Lepidoptera: Plutellidae), is one of the most economically damaging insect pests of cruciferous crops worldwide. This study characterized the biology and determined the number of larval instars of P. xylostella under controlled mountain laboratory conditions at 2,589 m a.s.l., mean temperature 16.9 ± 0.4°C, relative humidity 72.9 ± 3.1%, and dew point 12.1°C, using cabbage ( Brassica oleracea L. var. capitata ) as rearing host, at the Centro de Investigación en Sanidad Vegetal y Bioinsumos (CISVEB), Pamplona, Norte de Santander, Colombia. The total life cycle lasted 57.06 days (range 33–78 days): egg 9.11 ± 1.242 days; total larval period 19.54 ± 2.620 days; pupal stage 9.93 ± 1.698 days; adult longevity 18.48 ± 5.124 days. Four larval instars were confirmed by Dyar's Rule, with mean head capsule widths of 0.144, 0.253, 0.405, and 0.599 mm (Dyar's ratio mean = 1.61). Mean female fecundity was 43.67 eggs per female over 28 days. Extended developmental durations relative to warmer-climate studies are attributed to reduced thermal sum at high altitude. These data provide a biological baseline for integrated pest management (IPM) programs in Andean Brassicaceae production. Agronomy diamondback moth Brassicaceae larval instars Dyar's Rule high-altitude agroecosystem integrated pest management Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Key Message • Developmental biology of Plutella xylostella is poorly documented for Andean highlands above 2,500 m a.s.l., leaving IPM practitioners without altitude-specific biological benchmarks. • Four larval instars confirmed by Dyar's Rule; total life cycle (57.06 days) is 2–3× longer at 16.9°C/2,589 m than at warm lowland sites, with conserved head capsule dimensions across temperatures. • Reduced fecundity (43.67 eggs/female) and extended generation time at high altitude substantially curtail population growth, yet mild year-round temperatures permit continuous, overlapping generations. • These baseline biological data enable altitude-calibrated population models and inform optimal timing for IPM interventions in Andean Brassicaceae production. Introduction Plutella xylostella (Linnaeus, 1758) (Lepidoptera: Plutellidae), commonly known as the diamondback moth (DBM), is considered one of the most destructive insect pests of Brassicaceae worldwide. It attacks virtually all cultivated cruciferous crops, including cabbage ( Brassica oleracea L. var. capitata L.), cauliflower ( B. oleracea var. botrytis L.), broccoli ( B. oleracea var. italica Plenck), and radish ( Raphanus sativus L.). Global annual control costs are estimated to exceed US $ 4–5 billion (Furlong et al. 2013 ). In Colombia, Brassicaceae crops occupy more than 60,000 hectares, and DBM infestations are among the most constraining biotic factors for production, particularly in Andean highland regions where moderate temperatures and year-round cultivation provide near-continuous host availability (Ministerio de Agricultura y Desarrollo Rural 2022 ). Despite its global importance, the biology of P. xylostella is markedly influenced by temperature, altitude, and host plant quality (Golizadeh et al. 2007 ; Bahar et al. 2014 ). Studies at warm lowland temperatures (22–28°C) report a complete life cycle of approximately 19–38 days (Talekar and Shelton 1993 ; Jalali et al. 2011 ). However, data from Andean highlands (> 2,000 m a.s.l.) are scarce, and developmental parameters from lowland populations cannot be directly extrapolated to high-altitude agroecosystems where mean temperatures may fall below 17°C (Macharia et al. 2005 ; Ngowi et al. 2017 ). Larval instar determination based on head capsule width measurements and Dyar's Rule is a cornerstone of insect developmental biology, yet its reliability under thermal stress has been questioned. A recent bioassay conducted under comparable high-mountain laboratory conditions (17°C, 2,589 m a.s.l., Universidad de Pamplona) demonstrated that low altitude-associated temperatures substantially modify larval growth dynamics in Spodoptera frugiperda : developmental duration was markedly prolonged, overlap among successive head capsule width distributions increased, and a proportion of individuals exhibited supernumerary instars, indicating notable thermal plasticity (Giraldo-Vanegas et al. 2025 ). These findings underscore the need to validate Dyar's Rule criteria under altitude-specific conditions for each target species, as growth ratios derived from lowland studies may not accurately predict instar boundaries in Andean agroecosystems. The present study was conducted to (i) describe the morphological characteristics of all developmental stages of P. xylostella under controlled mountain laboratory conditions; (ii) quantify the duration of each developmental stage and larval instar; (iii) determine the number of larval instars using Dyar's Rule applied to head capsule width measurements, explicitly evaluating whether the canonical four-instar pattern is maintained or modified under thermal constraints; and (iv) estimate female fecundity. These data constitute the first detailed biological characterization of P. xylostella for the Andean highlands of Norte de Santander, Colombia, and contribute to an emerging body of evidence on altitude-driven developmental plasticity in Lepidoptera. Materials and Methods Study site and environmental conditions All experiments were conducted at the Plant Health Laboratory, Agronomy Engineering Program, Universidad de Pamplona (7°22′N, 72°39′W; 2,589 m a.s.l.). Temperature, relative humidity (RH), and dew point were continuously recorded with a calibrated data logger (TESTO 174H). Mean values: temperature 16.9 ± 0.4°C, RH 72.9 ± 3.1%, dew point 12.1°C. Insect collection and colony establishment Founder specimens of P. xylostella were collected from Brassicaceae plantations at CISVEB by direct visual search on adaxial and abaxial leaf surfaces of cabbage, cauliflower, and broccoli (08:00–11:00 h local time). Larvae were removed with a size-00 camel-hair brush; adults were collected by sweep netting. All stages were transported to the laboratory in ventilated glass vials. Adults were paired (1♀:1♂) in 500-mL rearing jars with fresh cabbage leaf; rearing continued for three generations before experimental cohorts were established. Rearing procedures Fresh cabbage ( B. oleracea var. capitata ) leaf discs (3 cm diameter) were surface-sterilized in 2% NaOCl for 2 min, rinsed, and air-dried. Each disc was placed on moist filter paper in a 9-cm Petri dish. A single newly hatched larva was assigned to each dish (one experimental unit). Both leaf disc and filter paper were replaced daily. Monitoring of developmental stages Each larva was examined daily to record ecdysis dates, exuviae recovery, and stage transitions. Exuviae were preserved individually in 1.5-mL microtubes with 70% ethanol, labeled with larva number and molt date. Stage durations recorded: egg incubation; each larval instar; pupal period; adult longevity. Determination of larval instars (Dyar's Rule) Head capsule widths (maximum lateral width across the genae) were measured on preserved exuviae using a calibrated ocular micrometer at 40× magnification (nearest 0.001 mm). Dyar's ratio was calculated as k = W(n + 1)/W(n). A ratio between 1.2 and 2.0 confirms a true instar boundary (Gaines and Campbell 1935 ; García-Caicedo et al. 2012 ). Given that altitude-associated low temperatures can alter head capsule growth patterns and cause instar overlap in Lepidoptera (Giraldo-Vanegas et al. 2025 ), frequency distributions of head capsule width were examined for multimodality, and Dyar's ratios were evaluated instar-by-instar to assess whether the geometric progression was maintained under the prevailing thermal conditions. Fecundity assessment Three adult pairs were monitored individually in 500-mL jars with fresh cabbage leaf for 28 days. Eggs per female per day, total eggs per female, and potential generations per 28 days were recorded. Statistical analysis Data are expressed as mean ± SD. Normality was assessed by the Shapiro–Wilk test. Differences among larval instar durations were evaluated by one-way ANOVA (Tukey HSD) or Kruskal–Wallis (Dunn's post hoc) for non-normal data (α = 0.05; R v4.4.0, R Core Team 2024 ). Results Morphological description of developmental stages Egg. Sub-spherical, pale yellowish-green at oviposition, darkening during development; 0.4 × 0.2 mm. Deposited singly or in small clutches (2–5 eggs) on the abaxial leaf surface. About 95% of eclosions occurred between 08:00 and 11:00 h. Larva I. Newly eclosed larvae were translucent-creamy (~ 1.5–1.7 mm), with a conspicuous dark head capsule. First instars immediately initiated leaf mining, tunneling through the spongy mesophyll and leaving characteristic translucent windows in the lamina. Posterior prolegs formed a distinctive V shape. Larva II. Slightly larger (~ 3.0–3.5 mm), pale, with more pronounced segmentation. Feeding shifted from mining to surface feeding on the abaxial leaf surface. Larva III. Grayish to pale green (5.0–7.0 mm); spiracles distinct. Third-instar larvae caused complete lamina defoliation, leaving only main leaf veins. Disturbance elicited vigorous writhing and suspension on silk threads. Larva IV. Bright green (8.0–11.2 mm); voracious feeding caused rapid extensive defoliation. Toward the end of L4, larvae became quiescent and constructed a loosely spun white silken cocoon on the leaf surface for pupation. Pupa. Obtect-type, visible through a loosely woven white cocoon (~ 6–8 mm). Coloration progressed from pale green to buff/orange to dark brown. Cocoons adhered firmly to the leaf lamina. Adult. Characteristic diamondback (rhomboidal) pattern visible along the dorsal forewing margin at rest; females slightly larger than males (sexual dimorphism). Adults were nocturnal/crepuscular, hiding under foliage during daylight. Duration of developmental stages Under experimental conditions, the total life cycle of P. xylostella lasted a mean of 57.06 days (range 33–78 days). Detailed stage durations are presented in Table 1 and Fig. 2A. Table 1 Duration (days) of developmental stages of Plutella xylostella (L.) reared on cabbage leaf discs under mountain laboratory conditions (16.9 ± 0.4°C; 72.9 ± 3.1% RH; 2,589 m a.s.l., Pamplona, Colombia). SD standard deviation Stage n Mean ± SD (days) Min Max Range Egg 66 9.11 ± 1.242 6 11 5 Larva (total) 37 19.54 ± 2.620 12 25 13 Pupa 28 9.93 ± 1.698 7 12 5 Adult longevity 25 18.48 ± 5.124 8 30 22 Total life cycle – 57.06 33 78 45 Duration of larval instars P. xylostella completed larval development through four distinct instars. Instar I had the shortest duration (3.35 ± 0.845 days; n = 63), followed by instar III (4.81 ± 1.607 days), instar IV (5.49 ± 1.239 days), and instar II (5.62 ± 2.019 days) (Table 2 ). Table 2 Duration (days) of each larval instar of P. xylostella reared on cabbage under mountain laboratory conditions. SD standard deviation Instar n Mean ± SD (days) Min (days) Max (days) I 63 3.35 ± 0.845 2 6 II 50 5.62 ± 2.019 2 9 III 43 4.81 ± 1.607 2 9 IV 37 5.49 ± 1.239 2 8 Head capsule width and instar determination Application of Dyar's Rule confirmed four larval instars, with successive modal peaks clearly separated in the frequency distribution (Fig. 1). Mean head capsule widths increased geometrically: 0.144 ± 0.04 mm (L1), 0.253 ± 0.02 mm (L2), 0.405 ± 0.01 mm (L3), and 0.599 ± 0.06 mm (L4) (Table 3 ). Dyar's ratios were 1.76 (L1→L2), 1.60 (L2→L3), and 1.48 (L3→L4), with grand mean 1.61, validating a true geometric progression (Fig. 4). Notably, instar boundaries remained well-differentiated with minimal overlap among head capsule width distributions, in contrast to the instar overlap and supernumerary instars observed in Spodoptera frugiperda reared under very similar high-altitude thermal conditions (17°C; Giraldo-Vanegas et al. 2025 ), suggesting that P. xylostella exhibits lower developmental plasticity in response to low temperature than S. frugiperda . Table 3 Mean (± SD) head capsule widths, instar ranges, and Dyar's ratios for each larval instar of P. xylostella . Measurements on preserved exuviae at 40× magnification Instar Mean ± SD (mm) Range (mm) Dyar's ratio I 0.144 ± 0.04 0.08–0.23 – II 0.253 ± 0.02 0.23–0.38 1.76 III 0.405 ± 0.01 0.38–0.53 1.60 IV 0.599 ± 0.06 0.53–0.68 1.48 Fecundity Female P. xylostella laid a mean of 10.15 eggs per day ( n = 13; SD = 12.575) and 43.67 ± 8.082 total eggs per female over 28 days ( n = 3 pairs), corresponding to an estimated 6.67 ± 1.155 potential generations per female within 28 days (Table 4 ). Table 4 Fecundity parameters of P. xylostella under mountain laboratory conditions (16.9°C; 72.9% RH; 2,589 m a.s.l.) Parameter n Mean SD Total eggs per female per day 13 10.15 12.575 Total eggs per female in 28 days 3 43.67 8.082 Generations per female in 28 days 3 6.67 1.155 Figure 1 Frequency distribution of head capsule width measurements (mm) across larval instars I–IV of Plutella xylostella (L.). Instar ranges: L1 (0.08–0.23 mm); L2 (0.23–0.38 mm); L3 (0.38–0.53 mm); L4 (0.53–0.68 mm). Measurements taken with a calibrated ocular micrometer (40×) from preserved exuviae. Dashed lines indicate instar boundaries. Conditions: 16.9°C, 72.9% RH, 2,589 m a.s.l., Pamplona, Colombia Figure 2 (A) Duration (days ± SD) of developmental stages and (B) larval instar durations of Plutella xylostella (L.) reared under mountain laboratory conditions (16.9°C, 72.9% RH, 2,589 m a.s.l., Pamplona, Colombia). Diamonds (◆) indicate mean head capsule widths (secondary axis, right panel) Figure 3 Schematic life cycle diagram of Plutella xylostella (L.) under mountain laboratory conditions (16.9°C, 72.9% RH, 2,589 m a.s.l., Pamplona, Norte de Santander, Colombia). Duration means (days ± SD) and sample sizes are indicated for each stage. HCW mean head capsule width for each larval instar Figure 4 Head capsule width progression across larval instars of Plutella xylostella (L.) on (A) linear scale with geometric fit (dashed line) and (B) logarithmic scale. Linear progression on the log scale validates Dyar's Rule. Values are mean ± SD; Dyar's ratios ( k ) indicated between instar pairs. Conditions: 16.9°C, 72.9% RH, 2,589 m a.s.l. Figure 5 Comparison of total life cycle duration (bars, left axis) and female fecundity (diamonds ◆, right axis) of Plutella xylostella (L.) across studies conducted at different temperatures. Temperature (°C) is shown above each bar. Data from: this study (16.9°C, 2,589 m a.s.l.); Fernández and Álvarez ( 1998 ); Talekar and Shelton ( 1993 ); Jalali et al. ( 2011 ) Discussion The total life cycle of 57.06 days observed here is approximately 2–3× longer than life cycles recorded at 22–26°C (19–38 days; Talekar and Shelton 1993 ; Jalali et al. 2011 ). This prolongation is consistent with the thermal biology of P. xylostella , whose developmental lower threshold is estimated between 6.7°C and 9.9°C (Golizadeh et al. 2007 ; Bahar et al. 2014 ). At 16.9°C, only a modest thermal excess is available per day, slowing all life stages proportionally (Ngowi et al. 2017 ), as illustrated by the comparative data presented in Fig. 5. This temperature-dependent developmental delay mirrors the pattern documented for other Lepidoptera at comparable high-altitude Andean sites: under nearly identical thermal conditions (17°C, 2,589 m a.s.l.), Spodoptera frugiperda showed total larval durations of 39–41 days compared with 14–22 days at 25–30°C (Giraldo-Vanegas et al. 2025 ), confirming that the thermal constraint imposed by altitude is a broadly acting constraint across Lepidoptera at this elevation. The confirmation of four larval instars via Dyar's Rule is consistent with all published reports for P. xylostella (Talekar and Shelton 1993 ; Jalali et al. 2011 ; Philips et al. 2014 ). The absolute head capsule widths recorded (L1 = 0.144 mm; L4 = 0.599 mm) closely match Fernández and Álvarez ( 1998 ) and Carvalho et al. ( 1999 ), suggesting that head capsule dimensions of P. xylostella are conserved across a broad temperature range, while only developmental time differs—validating head capsule measurements as a temperature-independent diagnostic tool for instar identification in Andean populations. This stability is noteworthy in light of the instar number variability and increased head capsule width overlap reported for S. frugiperda under similar high-mountain conditions, where a proportion of individuals produced supernumerary instars and growth ratios deviated from the classical Dyar's Rule expectation (Giraldo-Vanegas et al. 2025 ). The contrasting response suggests that P. xylostella possesses a more canalized developmental programme that resists low-temperature-induced plasticity, whereas polyphagous noctuids such as S. frugiperda display greater phenotypic flexibility. From a methodological standpoint, these interspecific differences reinforce the recommendation that Dyar's Rule criteria should be validated locally for each target species at high altitude, rather than relying on growth parameters established under lowland or optimal thermal conditions. Female fecundity (43.67 eggs per female over 28 days) was markedly lower than the 150–300 + eggs reported at optimal temperatures (Talekar and Shelton 1993 ; Furlong et al. 2013 ). Reduced fecundity combined with fewer potential generations within 28 days (6.67 vs. >10 at 22–26°C) suggests that the population growth potential of P. xylostella is substantially curtailed at high altitude. Nevertheless, even this reduced reproductive output, combined with the absence of winter diapause at Pamplona's mild climate, means multiple overlapping generations persist year-round—explaining the chronic nature of DBM infestations in the region. Taken together with findings on S. frugiperda thermal plasticity at the same site (Giraldo-Vanegas et al. 2025 ), these results highlight high-mountain agroecosystems in the Colombian Andes as environments where pest management models must be locally calibrated: reduced thermal sums simultaneously suppress reproduction and extend development, altering the timing of susceptible larval stages and, consequently, the optimal windows for biological and chemical interventions. Conclusions Plutella xylostella completes four larval instars under high-altitude mountain conditions in Pamplona, Norte de Santander (2,589 m a.s.l., 16.9°C), confirmed by Dyar's Rule. Head capsule width distributions were well-separated with minimal overlap, and growth ratios conformed to the canonical geometric progression, in contrast to the instar variability and supernumerary instars observed in Spodoptera frugiperda under comparable high-mountain thermal conditions (Giraldo-Vanegas et al. 2025 ). This interspecific difference suggests that P. xylostella exhibits low developmental plasticity at high altitude, making head capsule measurements a reliable, temperature-independent tool for instar diagnosis in Andean populations. The total life cycle of 57.06 days is approximately two to three times longer than at lower altitudes, owing to reduced thermal sum at this elevation. The extended developmental periods have practical implications for IPM program timing in Andean agroecosystems. These biological data provide a regional baseline for developing accurate population models and sustainable management strategies for P. xylostella in Colombian Andean Brassicaceae production. Declarations Competing interests The author declares no competing interests. Ethics approval This research did not involve human participants, human data, or vertebrate animals requiring formal ethical approval. Funding The author declares that no external funding was received for this study. Author Contribution Statement: HGV conceived and designed the research, conducted all experiments, collected and analyzed data, and wrote the manuscript. Acknowledgments The author thanks CISVEB staff and the Agronomy Engineering Program, Universidad de Pamplona, for technical and logistical support. Data availability The data supporting the findings of this study are available from the corresponding author upon reasonable request. References Bahar MH, Soroka JJ, Grenkow L, Dosdall LM (2014) New threshold temperatures for the development of a North American diamondback moth (Lepidoptera: Plutellidae) population and its larval parasitoid, Diadegma insulare (Hymenoptera: Ichneumonidae). Environ Entomol 43(6):1443–1452. https://doi.org/10.1603/EN14055 Birch LC (1948) The intrinsic rate of natural increase of an insect population. J Anim Ecol 17(1):15–26. https://doi.org/10.2307/1605 Carvalho CN, Filho MM, Picanco M (1999) Determinação do número de ínstares larvais em Plutella xylostella (L.) (Lepidoptera: Plutellidae). Acta Sci 21(2):331–335 Dyar HG (1890) The number of molts of lepidopterous larvae. Psyche J Entomol 5(175–176):420–422. https://doi.org/10.1155/1890/23634 Fernández AS, Álvarez C (1998) Biología de Plutella xylostella (L.) (Lepidoptera: Plutellidae), polilla del repollo ( Brassica oleracea L.) en condiciones de laboratorio. Agron Trop 38(4–6):17–28 Furlong MJ, Wright DJ, Dosdall LM (2013) Diamondback moth ecology and management: problems, progress, and prospects. Annu Rev Entomol 58:517–541. https://doi.org/10.1146/annurev-ento-120811-153605 Gaines JC, Campbell FL (1935) Dyar's rule as related to the number of instars of the corn earworm, Heliothis obsoleta (Fab). Ann Entomol Soc Am 28(4):445–461. https://doi.org/10.1093/aesa/28.4.445 García-Caicedo M, Giraldo-Vanegas H, Ochoa A (2012) Ciclo de vida de Metamasius dimidiatipennis Champeon (Coleoptera: Curculionidae) en condiciones de laboratorio. Agron Trop 62(1–4):69–75 Giraldo-Vanegas H, Núñez-García SN, Velásquez-López SM (2025) Influence of altitude on larval instar determination of Spodoptera frugiperda (Lepidoptera: Noctuidae) under high-mountain laboratory conditions. https://doi.org/10.21203/rs.3.rs-8876098/v1 . Preprint Golizadeh A, Kamali K, Fathipour Y, Abbasipour H (2007) Temperature-dependent development of diamondback moth, Plutella xylostella (Lepidoptera: Plutellidae) on two Brassicaceous host plants. Insect Sci 14(4):309–316. https://doi.org/10.1111/j.1744-7917.2007.00153.x Jalali MA, Tirry L, Arbabi M, De Clercq P (2011) Biological study of Plutella xylostella (L.) (Lep: Plutellidae) and its endoparasitoid, Cotesia vestalis (Haliday) (Hym: Braconidae) under laboratory conditions. Pak J Biol Sci 14(18):840–848. https://doi.org/10.3923/pjbs.2011.840.848 Macharia I, Löhr B, De Groote H (2005) Assessing the potential impact of biological control of Plutella xylostella in cabbage production in Kenya. Crop Prot 24(11):981–989. https://doi.org/10.1016/j.cropro.2005.01.012 Ministerio de Agricultura y Desarrollo Rural (2022) Agronet: Estadísticas agropecuarias. Gobierno de Colombia. https://www.agronet.gov.co Ngowi BV, Tonnang HEZ, Mwangi EM, Johansson T, Ambale J, Ndegwa PN, Subramanian S (2017) Temperature-dependent phenology of Plutella xylostella (Lepidoptera: Plutellidae): simulation and visualization along the Eastern Afromontane. PLoS ONE 12(3):e0173590. https://doi.org/10.1371/journal.pone.0173590 Philips CR, Fu Z, Kuhar TP, Shelton AM, Cordero RJ (2014) Natural history, ecology, and management of diamondback moth (Lepidoptera: Plutellidae). J Integr Pest Manag 5(3):1–12. https://doi.org/10.1603/IPM14008 R Core Team (2024) R: A language and environment for statistical computing (Version 4.4.0). R Foundation for Statistical Computing. https://www.R-project.org Talekar NS, Shelton AM (1993) Biology, ecology, and management of the diamondback moth. Annu Rev Entomol 38:275–301. https://doi.org/10.1146/annurev.en.38.010193.001423 Additional Declarations The authors declare no competing interests. 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. 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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-9534424\",\"acceptedTermsAndConditions\":true,\"allowDirectSubmit\":true,\"archivedVersions\":[],\"articleType\":\"Research Article\",\"associatedPublications\":[],\"authors\":[{\"id\":629848702,\"identity\":\"2e114b3d-1d10-4feb-98a1-7a783e84664b\",\"order_by\":0,\"name\":\"Humberto Giraldo-Vanegas\",\"email\":\"data:image/png;base64,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\",\"orcid\":\"https://orcid.org/0000-0002-0801-2714\",\"institution\":\"Universidad de Pamplona\",\"correspondingAuthor\":true,\"prefix\":\"\",\"firstName\":\"Humberto\",\"middleName\":\"\",\"lastName\":\"Giraldo-Vanegas\",\"suffix\":\"\"}],\"badges\":[],\"createdAt\":\"2026-04-26 20:42:34\",\"currentVersionCode\":1,\"declarations\":{\"humanSubjects\":false,\"vertebrateSubjects\":false,\"conflictsOfInterestStatement\":false,\"humanSubjectEthicalGuidelines\":false,\"humanSubjectConsent\":false,\"humanSubjectClinicalTrial\":false,\"humanSubjectCaseReport\":false,\"vertebrateSubjectEthicalGuidelines\":false},\"doi\":\"10.21203/rs.3.rs-9534424/v1\",\"doiUrl\":\"https://doi.org/10.21203/rs.3.rs-9534424/v1\",\"draftVersion\":[],\"editorialEvents\":[],\"editorialNote\":\"\",\"failedWorkflow\":false,\"files\":[{\"id\":107992796,\"identity\":\"21880f4d-db97-4bc4-b8b7-f5009ed13eb6\",\"added_by\":\"auto\",\"created_at\":\"2026-04-28 10:28:35\",\"extension\":\"png\",\"order_by\":1,\"title\":\"Figure 1\",\"display\":\"\",\"copyAsset\":false,\"role\":\"figure\",\"size\":167699,\"visible\":true,\"origin\":\"\",\"legend\":\"\\u003cp\\u003eFrequency distribution of head capsule width measurements (mm) across larval instars I–IV of \\u003cem\\u003ePlutella xylostella\\u003c/em\\u003e (L.). Instar ranges: L1 (0.08–0.23 mm); L2 (0.23–0.38 mm); L3 (0.38–0.53 mm); L4 (0.53–0.68 mm). Measurements taken with a calibrated ocular micrometer (40×) from preserved exuviae. Dashed lines indicate instar boundaries. Conditions: 16.9°C, 72.9% RH, 2,589 m a.s.l., Pamplona, Colombia\\u003c/p\\u003e\",\"description\":\"\",\"filename\":\"Fig1HeadCapsuleFrequency.png\",\"url\":\"https://assets-eu.researchsquare.com/files/rs-9534424/v1/00a27c656660f3fa2f28cb3a.png\"},{\"id\":108007258,\"identity\":\"c0ac4ec7-8e29-4714-8274-a263b2b45519\",\"added_by\":\"auto\",\"created_at\":\"2026-04-28 12:59:11\",\"extension\":\"png\",\"order_by\":2,\"title\":\"Figure 2\",\"display\":\"\",\"copyAsset\":false,\"role\":\"figure\",\"size\":228869,\"visible\":true,\"origin\":\"\",\"legend\":\"\\u003cp\\u003e(A) Duration (days ± SD) of developmental stages and (B) larval instar durations of \\u003cem\\u003ePlutella xylostella\\u003c/em\\u003e(L.) reared under mountain laboratory conditions (16.9°C, 72.9% RH, 2,589 m a.s.l., Pamplona, Colombia). Diamonds (◆) indicate mean head capsule widths (secondary axis, right panel)\\u003c/p\\u003e\",\"description\":\"\",\"filename\":\"Fig2DevelopmentalDuration.png\",\"url\":\"https://assets-eu.researchsquare.com/files/rs-9534424/v1/40749d7933613d9b14d9825e.png\"},{\"id\":108007426,\"identity\":\"bedb599e-82df-4116-82ca-69ae72400629\",\"added_by\":\"auto\",\"created_at\":\"2026-04-28 13:00:03\",\"extension\":\"png\",\"order_by\":3,\"title\":\"Figure 3\",\"display\":\"\",\"copyAsset\":false,\"role\":\"figure\",\"size\":310051,\"visible\":true,\"origin\":\"\",\"legend\":\"\\u003cp\\u003eSchematic life cycle diagram of \\u003cem\\u003ePlutella xylostella\\u003c/em\\u003e (L.) under mountain laboratory conditions (16.9°C, 72.9% RH, 2,589 m a.s.l., Pamplona, Norte de Santander, Colombia). Duration means (days ± SD) and sample sizes are indicated for each stage. HCW mean head capsule width for each larval instar\\u003c/p\\u003e\",\"description\":\"\",\"filename\":\"Fig3LifeCycleDiagram.png\",\"url\":\"https://assets-eu.researchsquare.com/files/rs-9534424/v1/2d2c2ec559954c3179f32186.png\"},{\"id\":107992798,\"identity\":\"257efb71-2e2a-4a4f-8edf-9f63fde06bee\",\"added_by\":\"auto\",\"created_at\":\"2026-04-28 10:28:35\",\"extension\":\"png\",\"order_by\":4,\"title\":\"Figure 4\",\"display\":\"\",\"copyAsset\":false,\"role\":\"figure\",\"size\":264193,\"visible\":true,\"origin\":\"\",\"legend\":\"\\u003cp\\u003eHead capsule width progression across larval instars of \\u003cem\\u003ePlutella xylostella\\u003c/em\\u003e (L.) on (A) linear scale with geometric fit (dashed line) and (B) logarithmic scale. Linear progression on the log scale validates Dyar's Rule. Values are mean ± SD; Dyar's ratios (\\u003cem\\u003ek\\u003c/em\\u003e) indicated between instar pairs. Conditions: 16.9°C, 72.9% RH, 2,589 m a.s.l.\\u003c/p\\u003e\",\"description\":\"\",\"filename\":\"Fig4DyarRule.png\",\"url\":\"https://assets-eu.researchsquare.com/files/rs-9534424/v1/552d840267e03701f232ba55.png\"},{\"id\":107992799,\"identity\":\"39122883-e7fd-4864-b1d1-dcbf8cb8e8fe\",\"added_by\":\"auto\",\"created_at\":\"2026-04-28 10:28:35\",\"extension\":\"png\",\"order_by\":5,\"title\":\"Figure 5\",\"display\":\"\",\"copyAsset\":false,\"role\":\"figure\",\"size\":268251,\"visible\":true,\"origin\":\"\",\"legend\":\"\\u003cp\\u003eComparison of total life cycle duration (bars, left axis) and female fecundity (diamonds ◆, right axis) of \\u003cem\\u003ePlutella xylostella\\u003c/em\\u003e (L.) across studies conducted at different temperatures. Temperature (°C) is shown above each bar. Data from: this study (16.9°C, 2,589 m a.s.l.); Fernández and Álvarez (1998); Talekar and Shelton (1993); Jalali et al. (2011)\\u003c/p\\u003e\",\"description\":\"\",\"filename\":\"Fig5ComparativeStudy.png\",\"url\":\"https://assets-eu.researchsquare.com/files/rs-9534424/v1/493dd8a268220555cb2a81b1.png\"},{\"id\":108181085,\"identity\":\"86748cb2-4355-4886-8f3b-cdc8b3449e04\",\"added_by\":\"auto\",\"created_at\":\"2026-04-30 08:57:06\",\"extension\":\"pdf\",\"order_by\":0,\"title\":\"\",\"display\":\"\",\"copyAsset\":false,\"role\":\"manuscript-pdf\",\"size\":1297165,\"visible\":true,\"origin\":\"\",\"legend\":\"\",\"description\":\"\",\"filename\":\"manuscript.pdf\",\"url\":\"https://assets-eu.researchsquare.com/files/rs-9534424/v1/245f5275-7225-4989-bb44-dd9736b5fbcb.pdf\"}],\"financialInterests\":\"The authors declare no competing interests.\",\"formattedTitle\":\"\\u003cp\\u003e\\u003cstrong\\u003eBiology and Determination of Larval Instars of \\u003c/strong\\u003e\\u003cem\\u003e\\u003cstrong\\u003ePlutella xylostella\\u003c/strong\\u003e\\u003c/em\\u003e\\u003cstrong\\u003e(Linnaeus, 1758) (Lepidoptera: Plutellidae) Under High-Altitude Mountain Laboratory Conditions in the Colombian Andes\\u003c/strong\\u003e\\u003c/p\\u003e\",\"fulltext\":[{\"header\":\"Key Message\",\"content\":\"\\u003cp\\u003e\\u003cstrong\\u003e•\\u0026nbsp;\\u003c/strong\\u003eDevelopmental biology of \\u003cem\\u003ePlutella xylostella\\u003c/em\\u003e is poorly documented for Andean highlands above 2,500 m a.s.l., leaving IPM practitioners without altitude-specific biological benchmarks.\\u003c/p\\u003e\\n\\u003cp\\u003e\\u003cstrong\\u003e•\\u0026nbsp;\\u003c/strong\\u003eFour larval instars confirmed by Dyar's Rule; total life cycle (57.06 days) is 2–3× longer at 16.9°C/2,589 m than at warm lowland sites, with conserved head capsule dimensions across temperatures.\\u003c/p\\u003e\\n\\u003cp\\u003e\\u003cstrong\\u003e•\\u0026nbsp;\\u003c/strong\\u003eReduced fecundity (43.67 eggs/female) and extended generation time at high altitude substantially curtail population growth, yet mild year-round temperatures permit continuous, overlapping generations.\\u003c/p\\u003e\\n\\u003cp\\u003e\\u003cstrong\\u003e•\\u0026nbsp;\\u003c/strong\\u003eThese baseline biological data enable altitude-calibrated population models and inform optimal timing for IPM interventions in Andean \\u003cem\\u003eBrassicaceae\\u003c/em\\u003e production.\\u003c/p\\u003e\"},{\"header\":\"Introduction\",\"content\":\"\\u003cp\\u003e \\u003cem\\u003ePlutella xylostella\\u003c/em\\u003e (Linnaeus, 1758) (Lepidoptera: Plutellidae), commonly known as the diamondback moth (DBM), is considered one of the most destructive insect pests of \\u003cem\\u003eBrassicaceae\\u003c/em\\u003e worldwide. It attacks virtually all cultivated cruciferous crops, including cabbage (\\u003cem\\u003eBrassica oleracea\\u003c/em\\u003e L. var. \\u003cem\\u003ecapitata\\u003c/em\\u003e L.), cauliflower (\\u003cem\\u003eB. oleracea\\u003c/em\\u003e var. \\u003cem\\u003ebotrytis\\u003c/em\\u003e L.), broccoli (\\u003cem\\u003eB. oleracea\\u003c/em\\u003e var. \\u003cem\\u003eitalica\\u003c/em\\u003e Plenck), and radish (\\u003cem\\u003eRaphanus sativus\\u003c/em\\u003e L.). Global annual control costs are estimated to exceed US\\u003cspan\\u003e$\\u003c/span\\u003e4\\u0026ndash;5\\u0026nbsp;billion (Furlong et al. \\u003cspan citationid=\\\"CR6\\\" class=\\\"CitationRef\\\"\\u003e2013\\u003c/span\\u003e). In Colombia, \\u003cem\\u003eBrassicaceae\\u003c/em\\u003e crops occupy more than 60,000 hectares, and DBM infestations are among the most constraining biotic factors for production, particularly in Andean highland regions where moderate temperatures and year-round cultivation provide near-continuous host availability (Ministerio de Agricultura y Desarrollo Rural \\u003cspan citationid=\\\"CR13\\\" class=\\\"CitationRef\\\"\\u003e2022\\u003c/span\\u003e).\\u003c/p\\u003e \\u003cp\\u003eDespite its global importance, the biology of \\u003cem\\u003eP. xylostella\\u003c/em\\u003e is markedly influenced by temperature, altitude, and host plant quality (Golizadeh et al. \\u003cspan citationid=\\\"CR10\\\" class=\\\"CitationRef\\\"\\u003e2007\\u003c/span\\u003e; Bahar et al. \\u003cspan citationid=\\\"CR1\\\" class=\\\"CitationRef\\\"\\u003e2014\\u003c/span\\u003e). Studies at warm lowland temperatures (22\\u0026ndash;28\\u0026deg;C) report a complete life cycle of approximately 19\\u0026ndash;38 days (Talekar and Shelton \\u003cspan citationid=\\\"CR17\\\" class=\\\"CitationRef\\\"\\u003e1993\\u003c/span\\u003e; Jalali et al. \\u003cspan citationid=\\\"CR11\\\" class=\\\"CitationRef\\\"\\u003e2011\\u003c/span\\u003e). However, data from Andean highlands (\\u0026gt;\\u0026thinsp;2,000 m a.s.l.) are scarce, and developmental parameters from lowland populations cannot be directly extrapolated to high-altitude agroecosystems where mean temperatures may fall below 17\\u0026deg;C (Macharia et al. \\u003cspan citationid=\\\"CR12\\\" class=\\\"CitationRef\\\"\\u003e2005\\u003c/span\\u003e; Ngowi et al. \\u003cspan citationid=\\\"CR14\\\" class=\\\"CitationRef\\\"\\u003e2017\\u003c/span\\u003e).\\u003c/p\\u003e \\u003cp\\u003eLarval instar determination based on head capsule width measurements and Dyar's Rule is a cornerstone of insect developmental biology, yet its reliability under thermal stress has been questioned. A recent bioassay conducted under comparable high-mountain laboratory conditions (17\\u0026deg;C, 2,589 m a.s.l., Universidad de Pamplona) demonstrated that low altitude-associated temperatures substantially modify larval growth dynamics in \\u003cem\\u003eSpodoptera frugiperda\\u003c/em\\u003e: developmental duration was markedly prolonged, overlap among successive head capsule width distributions increased, and a proportion of individuals exhibited supernumerary instars, indicating notable thermal plasticity (Giraldo-Vanegas et al. \\u003cspan citationid=\\\"CR9\\\" class=\\\"CitationRef\\\"\\u003e2025\\u003c/span\\u003e). These findings underscore the need to validate Dyar's Rule criteria under altitude-specific conditions for each target species, as growth ratios derived from lowland studies may not accurately predict instar boundaries in Andean agroecosystems.\\u003c/p\\u003e \\u003cp\\u003eThe present study was conducted to (i) describe the morphological characteristics of all developmental stages of \\u003cem\\u003eP. xylostella\\u003c/em\\u003e under controlled mountain laboratory conditions; (ii) quantify the duration of each developmental stage and larval instar; (iii) determine the number of larval instars using Dyar's Rule applied to head capsule width measurements, explicitly evaluating whether the canonical four-instar pattern is maintained or modified under thermal constraints; and (iv) estimate female fecundity. These data constitute the first detailed biological characterization of \\u003cem\\u003eP. xylostella\\u003c/em\\u003e for the Andean highlands of Norte de Santander, Colombia, and contribute to an emerging body of evidence on altitude-driven developmental plasticity in Lepidoptera.\\u003c/p\\u003e\"},{\"header\":\"Materials and Methods\",\"content\":\"\\u003cdiv id=\\\"Sec3\\\" class=\\\"Section2\\\"\\u003e \\u003ch2\\u003eStudy site and environmental conditions\\u003c/h2\\u003e \\u003cp\\u003eAll experiments were conducted at the Plant Health Laboratory, Agronomy Engineering Program, Universidad de Pamplona (7\\u0026deg;22\\u0026prime;N, 72\\u0026deg;39\\u0026prime;W; 2,589 m a.s.l.). Temperature, relative humidity (RH), and dew point were continuously recorded with a calibrated data logger (TESTO 174H). Mean values: temperature 16.9\\u0026thinsp;\\u0026plusmn;\\u0026thinsp;0.4\\u0026deg;C, RH 72.9\\u0026thinsp;\\u0026plusmn;\\u0026thinsp;3.1%, dew point 12.1\\u0026deg;C.\\u003c/p\\u003e \\u003c/div\\u003e\\n\\u003ch3\\u003eInsect collection and colony establishment\\u003c/h3\\u003e\\n\\u003cp\\u003eFounder specimens of \\u003cem\\u003eP. xylostella\\u003c/em\\u003e were collected from \\u003cem\\u003eBrassicaceae\\u003c/em\\u003e plantations at CISVEB by direct visual search on adaxial and abaxial leaf surfaces of cabbage, cauliflower, and broccoli (08:00\\u0026ndash;11:00 h local time). Larvae were removed with a size-00 camel-hair brush; adults were collected by sweep netting. All stages were transported to the laboratory in ventilated glass vials. Adults were paired (1♀:1♂) in 500-mL rearing jars with fresh cabbage leaf; rearing continued for three generations before experimental cohorts were established.\\u003c/p\\u003e\\n\\u003ch3\\u003eRearing procedures\\u003c/h3\\u003e\\n\\u003cp\\u003eFresh cabbage (\\u003cem\\u003eB. oleracea\\u003c/em\\u003e var. \\u003cem\\u003ecapitata\\u003c/em\\u003e) leaf discs (3 cm diameter) were surface-sterilized in 2% NaOCl for 2 min, rinsed, and air-dried. Each disc was placed on moist filter paper in a 9-cm Petri dish. A single newly hatched larva was assigned to each dish (one experimental unit). Both leaf disc and filter paper were replaced daily.\\u003c/p\\u003e\\n\\u003ch3\\u003eMonitoring of developmental stages\\u003c/h3\\u003e\\n\\u003cp\\u003eEach larva was examined daily to record ecdysis dates, exuviae recovery, and stage transitions. Exuviae were preserved individually in 1.5-mL microtubes with 70% ethanol, labeled with larva number and molt date. Stage durations recorded: egg incubation; each larval instar; pupal period; adult longevity.\\u003c/p\\u003e\\n\\u003ch3\\u003eDetermination of larval instars (Dyar's Rule)\\u003c/h3\\u003e\\n\\u003cp\\u003eHead capsule widths (maximum lateral width across the genae) were measured on preserved exuviae using a calibrated ocular micrometer at 40\\u0026times; magnification (nearest 0.001 mm). Dyar's ratio was calculated as \\u003cem\\u003ek\\u003c/em\\u003e\\u0026thinsp;=\\u0026thinsp;W(n\\u0026thinsp;+\\u0026thinsp;1)/W(n). A ratio between 1.2 and 2.0 confirms a true instar boundary (Gaines and Campbell \\u003cspan citationid=\\\"CR7\\\" class=\\\"CitationRef\\\"\\u003e1935\\u003c/span\\u003e; Garc\\u0026iacute;a-Caicedo et al. \\u003cspan citationid=\\\"CR8\\\" class=\\\"CitationRef\\\"\\u003e2012\\u003c/span\\u003e). Given that altitude-associated low temperatures can alter head capsule growth patterns and cause instar overlap in Lepidoptera (Giraldo-Vanegas et al. \\u003cspan citationid=\\\"CR9\\\" class=\\\"CitationRef\\\"\\u003e2025\\u003c/span\\u003e), frequency distributions of head capsule width were examined for multimodality, and Dyar's ratios were evaluated instar-by-instar to assess whether the geometric progression was maintained under the prevailing thermal conditions.\\u003c/p\\u003e \\u003cdiv id=\\\"Sec8\\\" class=\\\"Section2\\\"\\u003e \\u003ch2\\u003eFecundity assessment\\u003c/h2\\u003e \\u003cp\\u003eThree adult pairs were monitored individually in 500-mL jars with fresh cabbage leaf for 28 days. Eggs per female per day, total eggs per female, and potential generations per 28 days were recorded.\\u003c/p\\u003e \\u003c/div\\u003e \\u003cdiv id=\\\"Sec9\\\" class=\\\"Section2\\\"\\u003e \\u003ch2\\u003eStatistical analysis\\u003c/h2\\u003e \\u003cp\\u003eData are expressed as mean\\u0026thinsp;\\u0026plusmn;\\u0026thinsp;SD. Normality was assessed by the Shapiro\\u0026ndash;Wilk test. Differences among larval instar durations were evaluated by one-way ANOVA (Tukey HSD) or Kruskal\\u0026ndash;Wallis (Dunn's post hoc) for non-normal data (α\\u0026thinsp;=\\u0026thinsp;0.05; R v4.4.0, R Core Team \\u003cspan citationid=\\\"CR16\\\" class=\\\"CitationRef\\\"\\u003e2024\\u003c/span\\u003e).\\u003c/p\\u003e \\u003c/div\\u003e\"},{\"header\":\"Results\",\"content\":\"\\u003cdiv id=\\\"Sec11\\\" class=\\\"Section2\\\"\\u003e \\u003ch2\\u003eMorphological description of developmental stages\\u003c/h2\\u003e \\u003cp\\u003e \\u003cb\\u003eEgg.\\u003c/b\\u003e Sub-spherical, pale yellowish-green at oviposition, darkening during development; 0.4 \\u0026times; 0.2 mm. Deposited singly or in small clutches (2\\u0026ndash;5 eggs) on the abaxial leaf surface. About 95% of eclosions occurred between 08:00 and 11:00 h.\\u003c/p\\u003e \\u003cp\\u003e \\u003cb\\u003eLarva I.\\u003c/b\\u003e Newly eclosed larvae were translucent-creamy (~\\u0026thinsp;1.5\\u0026ndash;1.7 mm), with a conspicuous dark head capsule. First instars immediately initiated leaf mining, tunneling through the spongy mesophyll and leaving characteristic translucent windows in the lamina. Posterior prolegs formed a distinctive V shape.\\u003c/p\\u003e \\u003cp\\u003e \\u003cb\\u003eLarva II.\\u003c/b\\u003e Slightly larger (~\\u0026thinsp;3.0\\u0026ndash;3.5 mm), pale, with more pronounced segmentation. Feeding shifted from mining to surface feeding on the abaxial leaf surface.\\u003c/p\\u003e \\u003cp\\u003e \\u003cb\\u003eLarva III.\\u003c/b\\u003e Grayish to pale green (5.0\\u0026ndash;7.0 mm); spiracles distinct. Third-instar larvae caused complete lamina defoliation, leaving only main leaf veins. Disturbance elicited vigorous writhing and suspension on silk threads.\\u003c/p\\u003e \\u003cp\\u003e \\u003cb\\u003eLarva IV.\\u003c/b\\u003e Bright green (8.0\\u0026ndash;11.2 mm); voracious feeding caused rapid extensive defoliation. Toward the end of L4, larvae became quiescent and constructed a loosely spun white silken cocoon on the leaf surface for pupation.\\u003c/p\\u003e \\u003cp\\u003e \\u003cb\\u003ePupa.\\u003c/b\\u003e Obtect-type, visible through a loosely woven white cocoon (~\\u0026thinsp;6\\u0026ndash;8 mm). Coloration progressed from pale green to buff/orange to dark brown. Cocoons adhered firmly to the leaf lamina.\\u003c/p\\u003e \\u003cp\\u003e \\u003cb\\u003eAdult.\\u003c/b\\u003e Characteristic diamondback (rhomboidal) pattern visible along the dorsal forewing margin at rest; females slightly larger than males (sexual dimorphism). Adults were nocturnal/crepuscular, hiding under foliage during daylight.\\u003c/p\\u003e \\u003c/div\\u003e \\u003cdiv id=\\\"Sec12\\\" class=\\\"Section2\\\"\\u003e \\u003ch2\\u003eDuration of developmental stages\\u003c/h2\\u003e \\u003cp\\u003eUnder experimental conditions, the total life cycle of \\u003cem\\u003eP. xylostella\\u003c/em\\u003e lasted a mean of 57.06 days (range 33\\u0026ndash;78 days). Detailed stage durations are presented in Table\\u0026nbsp;\\u003cspan refid=\\\"Tab1\\\" class=\\\"InternalRef\\\"\\u003e1\\u003c/span\\u003e and Fig.\\u0026nbsp;2A.\\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\\u003eDuration (days) of developmental stages of \\u003cem\\u003ePlutella xylostella\\u003c/em\\u003e (L.) reared on cabbage leaf discs under mountain laboratory conditions (16.9\\u0026thinsp;\\u0026plusmn;\\u0026thinsp;0.4\\u0026deg;C; 72.9\\u0026thinsp;\\u0026plusmn;\\u0026thinsp;3.1% RH; 2,589 m a.s.l., Pamplona, Colombia). SD standard deviation\\u003c/p\\u003e \\u003c/div\\u003e \\u003c/caption\\u003e \\u003ccolgroup cols=\\\"6\\\"\\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=\\\"char\\\" char=\\\".\\\" class=\\\"colspec\\\" colname=\\\"c4\\\" colnum=\\\"4\\\"\\u003e\\u003c/div\\u003e \\u003cdiv align=\\\"char\\\" char=\\\".\\\" class=\\\"colspec\\\" colname=\\\"c5\\\" colnum=\\\"5\\\"\\u003e\\u003c/div\\u003e \\u003cdiv align=\\\"char\\\" char=\\\".\\\" class=\\\"colspec\\\" colname=\\\"c6\\\" colnum=\\\"6\\\"\\u003e\\u003c/div\\u003e \\u003cthead\\u003e \\u003ctr\\u003e \\u003cth align=\\\"left\\\" colname=\\\"c1\\\"\\u003e \\u003cp\\u003eStage\\u003c/p\\u003e \\u003c/th\\u003e \\u003cth align=\\\"left\\\" colname=\\\"c2\\\"\\u003e \\u003cp\\u003en\\u003c/p\\u003e \\u003c/th\\u003e \\u003cth align=\\\"left\\\" colname=\\\"c3\\\"\\u003e \\u003cp\\u003eMean\\u0026thinsp;\\u0026plusmn;\\u0026thinsp;SD (days)\\u003c/p\\u003e \\u003c/th\\u003e \\u003cth align=\\\"left\\\" colname=\\\"c4\\\"\\u003e \\u003cp\\u003eMin\\u003c/p\\u003e \\u003c/th\\u003e \\u003cth align=\\\"left\\\" colname=\\\"c5\\\"\\u003e \\u003cp\\u003eMax\\u003c/p\\u003e \\u003c/th\\u003e \\u003cth align=\\\"left\\\" colname=\\\"c6\\\"\\u003e \\u003cp\\u003eRange\\u003c/p\\u003e \\u003c/th\\u003e \\u003c/tr\\u003e \\u003c/thead\\u003e \\u003ctbody\\u003e \\u003ctr\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c1\\\"\\u003e \\u003cp\\u003eEgg\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c2\\\"\\u003e \\u003cp\\u003e66\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c3\\\"\\u003e \\u003cp\\u003e9.11\\u0026thinsp;\\u0026plusmn;\\u0026thinsp;1.242\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c4\\\"\\u003e \\u003cp\\u003e6\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c5\\\"\\u003e \\u003cp\\u003e11\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c6\\\"\\u003e \\u003cp\\u003e5\\u003c/p\\u003e \\u003c/td\\u003e \\u003c/tr\\u003e \\u003ctr\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c1\\\"\\u003e \\u003cp\\u003eLarva (total)\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c2\\\"\\u003e \\u003cp\\u003e37\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c3\\\"\\u003e \\u003cp\\u003e19.54\\u0026thinsp;\\u0026plusmn;\\u0026thinsp;2.620\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c4\\\"\\u003e \\u003cp\\u003e12\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c5\\\"\\u003e \\u003cp\\u003e25\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c6\\\"\\u003e \\u003cp\\u003e13\\u003c/p\\u003e \\u003c/td\\u003e \\u003c/tr\\u003e \\u003ctr\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c1\\\"\\u003e \\u003cp\\u003ePupa\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c2\\\"\\u003e \\u003cp\\u003e28\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c3\\\"\\u003e \\u003cp\\u003e9.93\\u0026thinsp;\\u0026plusmn;\\u0026thinsp;1.698\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c4\\\"\\u003e \\u003cp\\u003e7\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c5\\\"\\u003e \\u003cp\\u003e12\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c6\\\"\\u003e \\u003cp\\u003e5\\u003c/p\\u003e \\u003c/td\\u003e \\u003c/tr\\u003e \\u003ctr\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c1\\\"\\u003e \\u003cp\\u003eAdult longevity\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c2\\\"\\u003e \\u003cp\\u003e25\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c3\\\"\\u003e \\u003cp\\u003e18.48\\u0026thinsp;\\u0026plusmn;\\u0026thinsp;5.124\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c4\\\"\\u003e \\u003cp\\u003e8\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c5\\\"\\u003e \\u003cp\\u003e30\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c6\\\"\\u003e \\u003cp\\u003e22\\u003c/p\\u003e \\u003c/td\\u003e \\u003c/tr\\u003e \\u003ctr\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c1\\\"\\u003e \\u003cp\\u003e\\u003cb\\u003eTotal life cycle\\u003c/b\\u003e\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c2\\\"\\u003e \\u003cp\\u003e\\u0026ndash;\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c3\\\"\\u003e \\u003cp\\u003e\\u003cb\\u003e57.06\\u003c/b\\u003e\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c4\\\"\\u003e \\u003cp\\u003e33\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c5\\\"\\u003e \\u003cp\\u003e78\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c6\\\"\\u003e \\u003cp\\u003e45\\u003c/p\\u003e \\u003c/td\\u003e \\u003c/tr\\u003e \\u003c/tbody\\u003e \\u003c/colgroup\\u003e \\u003c/table\\u003e\\u003c/div\\u003e \\u003c/p\\u003e \\u003c/div\\u003e \\u003cdiv id=\\\"Sec13\\\" class=\\\"Section2\\\"\\u003e \\u003ch2\\u003eDuration of larval instars\\u003c/h2\\u003e \\u003cp\\u003e \\u003cem\\u003eP. xylostella\\u003c/em\\u003e completed larval development through four distinct instars. Instar I had the shortest duration (3.35\\u0026thinsp;\\u0026plusmn;\\u0026thinsp;0.845 days; \\u003cem\\u003en\\u003c/em\\u003e\\u0026thinsp;=\\u0026thinsp;63), followed by instar III (4.81\\u0026thinsp;\\u0026plusmn;\\u0026thinsp;1.607 days), instar IV (5.49\\u0026thinsp;\\u0026plusmn;\\u0026thinsp;1.239 days), and instar II (5.62\\u0026thinsp;\\u0026plusmn;\\u0026thinsp;2.019 days) (Table\\u0026nbsp;\\u003cspan refid=\\\"Tab2\\\" class=\\\"InternalRef\\\"\\u003e2\\u003c/span\\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\\u003eDuration (days) of each larval instar of \\u003cem\\u003eP. xylostella\\u003c/em\\u003e reared on cabbage under mountain laboratory conditions. SD standard deviation\\u003c/p\\u003e \\u003c/div\\u003e \\u003c/caption\\u003e \\u003ccolgroup cols=\\\"5\\\"\\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=\\\"char\\\" char=\\\"\\u0026plusmn;\\\" class=\\\"colspec\\\" colname=\\\"c3\\\" colnum=\\\"3\\\"\\u003e\\u003c/div\\u003e \\u003cdiv align=\\\"char\\\" char=\\\".\\\" class=\\\"colspec\\\" colname=\\\"c4\\\" colnum=\\\"4\\\"\\u003e\\u003c/div\\u003e \\u003cdiv align=\\\"char\\\" char=\\\".\\\" class=\\\"colspec\\\" colname=\\\"c5\\\" colnum=\\\"5\\\"\\u003e\\u003c/div\\u003e \\u003cthead\\u003e \\u003ctr\\u003e \\u003cth align=\\\"left\\\" colname=\\\"c1\\\"\\u003e \\u003cp\\u003eInstar\\u003c/p\\u003e \\u003c/th\\u003e \\u003cth align=\\\"left\\\" colname=\\\"c2\\\"\\u003e \\u003cp\\u003en\\u003c/p\\u003e \\u003c/th\\u003e \\u003cth align=\\\"left\\\" colname=\\\"c3\\\"\\u003e \\u003cp\\u003eMean\\u0026thinsp;\\u0026plusmn;\\u0026thinsp;SD (days)\\u003c/p\\u003e \\u003c/th\\u003e \\u003cth align=\\\"left\\\" colname=\\\"c4\\\"\\u003e \\u003cp\\u003eMin (days)\\u003c/p\\u003e \\u003c/th\\u003e \\u003cth align=\\\"left\\\" colname=\\\"c5\\\"\\u003e \\u003cp\\u003eMax (days)\\u003c/p\\u003e \\u003c/th\\u003e \\u003c/tr\\u003e \\u003c/thead\\u003e \\u003ctbody\\u003e \\u003ctr\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c1\\\"\\u003e \\u003cp\\u003eI\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c2\\\"\\u003e \\u003cp\\u003e63\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\"\\u0026plusmn;\\\" colname=\\\"c3\\\"\\u003e \\u003cp\\u003e3.35\\u0026thinsp;\\u0026plusmn;\\u0026thinsp;0.845\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c4\\\"\\u003e \\u003cp\\u003e2\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c5\\\"\\u003e \\u003cp\\u003e6\\u003c/p\\u003e \\u003c/td\\u003e \\u003c/tr\\u003e \\u003ctr\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c1\\\"\\u003e \\u003cp\\u003eII\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c2\\\"\\u003e \\u003cp\\u003e50\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\"\\u0026plusmn;\\\" colname=\\\"c3\\\"\\u003e \\u003cp\\u003e5.62\\u0026thinsp;\\u0026plusmn;\\u0026thinsp;2.019\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c4\\\"\\u003e \\u003cp\\u003e2\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c5\\\"\\u003e \\u003cp\\u003e9\\u003c/p\\u003e \\u003c/td\\u003e \\u003c/tr\\u003e \\u003ctr\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c1\\\"\\u003e \\u003cp\\u003eIII\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c2\\\"\\u003e \\u003cp\\u003e43\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\"\\u0026plusmn;\\\" colname=\\\"c3\\\"\\u003e \\u003cp\\u003e4.81\\u0026thinsp;\\u0026plusmn;\\u0026thinsp;1.607\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c4\\\"\\u003e \\u003cp\\u003e2\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c5\\\"\\u003e \\u003cp\\u003e9\\u003c/p\\u003e \\u003c/td\\u003e \\u003c/tr\\u003e \\u003ctr\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c1\\\"\\u003e \\u003cp\\u003eIV\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c2\\\"\\u003e \\u003cp\\u003e37\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\"\\u0026plusmn;\\\" colname=\\\"c3\\\"\\u003e \\u003cp\\u003e5.49\\u0026thinsp;\\u0026plusmn;\\u0026thinsp;1.239\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c4\\\"\\u003e \\u003cp\\u003e2\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c5\\\"\\u003e \\u003cp\\u003e8\\u003c/p\\u003e \\u003c/td\\u003e \\u003c/tr\\u003e \\u003c/tbody\\u003e \\u003c/colgroup\\u003e \\u003c/table\\u003e\\u003c/div\\u003e \\u003c/p\\u003e \\u003c/div\\u003e \\u003cdiv id=\\\"Sec14\\\" class=\\\"Section2\\\"\\u003e \\u003ch2\\u003eHead capsule width and instar determination\\u003c/h2\\u003e \\u003cp\\u003eApplication of Dyar's Rule confirmed four larval instars, with successive modal peaks clearly separated in the frequency distribution (Fig.\\u0026nbsp;1). Mean head capsule widths increased geometrically: 0.144\\u0026thinsp;\\u0026plusmn;\\u0026thinsp;0.04 mm (L1), 0.253\\u0026thinsp;\\u0026plusmn;\\u0026thinsp;0.02 mm (L2), 0.405\\u0026thinsp;\\u0026plusmn;\\u0026thinsp;0.01 mm (L3), and 0.599\\u0026thinsp;\\u0026plusmn;\\u0026thinsp;0.06 mm (L4) (Table\\u0026nbsp;\\u003cspan refid=\\\"Tab3\\\" class=\\\"InternalRef\\\"\\u003e3\\u003c/span\\u003e). Dyar's ratios were 1.76 (L1\\u0026rarr;L2), 1.60 (L2\\u0026rarr;L3), and 1.48 (L3\\u0026rarr;L4), with grand mean 1.61, validating a true geometric progression (Fig.\\u0026nbsp;4). Notably, instar boundaries remained well-differentiated with minimal overlap among head capsule width distributions, in contrast to the instar overlap and supernumerary instars observed in \\u003cem\\u003eSpodoptera frugiperda\\u003c/em\\u003e reared under very similar high-altitude thermal conditions (17\\u0026deg;C; Giraldo-Vanegas et al. \\u003cspan citationid=\\\"CR9\\\" class=\\\"CitationRef\\\"\\u003e2025\\u003c/span\\u003e), suggesting that \\u003cem\\u003eP. xylostella\\u003c/em\\u003e exhibits lower developmental plasticity in response to low temperature than \\u003cem\\u003eS. frugiperda\\u003c/em\\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\\u003eMean (\\u0026plusmn;\\u0026thinsp;SD) head capsule widths, instar ranges, and Dyar's ratios for each larval instar of \\u003cem\\u003eP. xylostella\\u003c/em\\u003e. Measurements on preserved exuviae at 40\\u0026times; magnification\\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=\\\"\\u0026plusmn;\\\" class=\\\"colspec\\\" colname=\\\"c2\\\" colnum=\\\"2\\\"\\u003e\\u003c/div\\u003e \\u003cdiv align=\\\"char\\\" char=\\\".\\\" 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\\u003eInstar\\u003c/p\\u003e \\u003c/th\\u003e \\u003cth align=\\\"left\\\" colname=\\\"c2\\\"\\u003e \\u003cp\\u003eMean\\u0026thinsp;\\u0026plusmn;\\u0026thinsp;SD (mm)\\u003c/p\\u003e \\u003c/th\\u003e \\u003cth align=\\\"left\\\" colname=\\\"c3\\\"\\u003e \\u003cp\\u003eRange (mm)\\u003c/p\\u003e \\u003c/th\\u003e \\u003cth align=\\\"left\\\" colname=\\\"c4\\\"\\u003e \\u003cp\\u003eDyar's ratio\\u003c/p\\u003e \\u003c/th\\u003e \\u003c/tr\\u003e \\u003c/thead\\u003e \\u003ctbody\\u003e \\u003ctr\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c1\\\"\\u003e \\u003cp\\u003eI\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\"\\u0026plusmn;\\\" colname=\\\"c2\\\"\\u003e \\u003cp\\u003e0.144\\u0026thinsp;\\u0026plusmn;\\u0026thinsp;0.04\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c3\\\"\\u003e \\u003cp\\u003e0.08\\u0026ndash;0.23\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c4\\\"\\u003e \\u003cp\\u003e\\u0026ndash;\\u003c/p\\u003e \\u003c/td\\u003e \\u003c/tr\\u003e \\u003ctr\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c1\\\"\\u003e \\u003cp\\u003eII\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\"\\u0026plusmn;\\\" colname=\\\"c2\\\"\\u003e \\u003cp\\u003e0.253\\u0026thinsp;\\u0026plusmn;\\u0026thinsp;0.02\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c3\\\"\\u003e \\u003cp\\u003e0.23\\u0026ndash;0.38\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c4\\\"\\u003e \\u003cp\\u003e1.76\\u003c/p\\u003e \\u003c/td\\u003e \\u003c/tr\\u003e \\u003ctr\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c1\\\"\\u003e \\u003cp\\u003eIII\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\"\\u0026plusmn;\\\" colname=\\\"c2\\\"\\u003e \\u003cp\\u003e0.405\\u0026thinsp;\\u0026plusmn;\\u0026thinsp;0.01\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c3\\\"\\u003e \\u003cp\\u003e0.38\\u0026ndash;0.53\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c4\\\"\\u003e \\u003cp\\u003e1.60\\u003c/p\\u003e \\u003c/td\\u003e \\u003c/tr\\u003e \\u003ctr\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c1\\\"\\u003e \\u003cp\\u003eIV\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\"\\u0026plusmn;\\\" colname=\\\"c2\\\"\\u003e \\u003cp\\u003e0.599\\u0026thinsp;\\u0026plusmn;\\u0026thinsp;0.06\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c3\\\"\\u003e \\u003cp\\u003e0.53\\u0026ndash;0.68\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c4\\\"\\u003e \\u003cp\\u003e1.48\\u003c/p\\u003e \\u003c/td\\u003e \\u003c/tr\\u003e \\u003c/tbody\\u003e \\u003c/colgroup\\u003e \\u003c/table\\u003e\\u003c/div\\u003e \\u003c/p\\u003e \\u003c/div\\u003e \\u003cdiv id=\\\"Sec15\\\" class=\\\"Section2\\\"\\u003e \\u003ch2\\u003eFecundity\\u003c/h2\\u003e \\u003cp\\u003eFemale \\u003cem\\u003eP. xylostella\\u003c/em\\u003e laid a mean of 10.15 eggs per day (\\u003cem\\u003en\\u003c/em\\u003e\\u0026thinsp;=\\u0026thinsp;13; SD\\u0026thinsp;=\\u0026thinsp;12.575) and 43.67\\u0026thinsp;\\u0026plusmn;\\u0026thinsp;8.082 total eggs per female over 28 days (\\u003cem\\u003en\\u003c/em\\u003e\\u0026thinsp;=\\u0026thinsp;3 pairs), corresponding to an estimated 6.67\\u0026thinsp;\\u0026plusmn;\\u0026thinsp;1.155 potential generations per female within 28 days (Table\\u0026nbsp;\\u003cspan refid=\\\"Tab4\\\" class=\\\"InternalRef\\\"\\u003e4\\u003c/span\\u003e).\\u003c/p\\u003e \\u003cp\\u003e \\u003cdiv class=\\\"gridtable\\\"\\u003e\\u003ctable float=\\\"Yes\\\" id=\\\"Tab4\\\" border=\\\"1\\\"\\u003e \\u003ccaption language=\\\"En\\\"\\u003e \\u003cdiv class=\\\"CaptionNumber\\\"\\u003eTable 4\\u003c/div\\u003e \\u003cdiv class=\\\"CaptionContent\\\"\\u003e \\u003cp\\u003eFecundity parameters of \\u003cem\\u003eP. xylostella\\u003c/em\\u003e under mountain laboratory conditions (16.9\\u0026deg;C; 72.9% RH; 2,589 m a.s.l.)\\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=\\\"char\\\" char=\\\".\\\" 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\\u003eParameter\\u003c/p\\u003e \\u003c/th\\u003e \\u003cth align=\\\"left\\\" colname=\\\"c2\\\"\\u003e \\u003cp\\u003en\\u003c/p\\u003e \\u003c/th\\u003e \\u003cth align=\\\"left\\\" colname=\\\"c3\\\"\\u003e \\u003cp\\u003eMean\\u003c/p\\u003e \\u003c/th\\u003e \\u003cth align=\\\"left\\\" colname=\\\"c4\\\"\\u003e \\u003cp\\u003eSD\\u003c/p\\u003e \\u003c/th\\u003e \\u003c/tr\\u003e \\u003c/thead\\u003e \\u003ctbody\\u003e \\u003ctr\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c1\\\"\\u003e \\u003cp\\u003eTotal eggs per female per day\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c2\\\"\\u003e \\u003cp\\u003e13\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c3\\\"\\u003e \\u003cp\\u003e10.15\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c4\\\"\\u003e \\u003cp\\u003e12.575\\u003c/p\\u003e \\u003c/td\\u003e \\u003c/tr\\u003e \\u003ctr\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c1\\\"\\u003e \\u003cp\\u003eTotal eggs per female in 28 days\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c2\\\"\\u003e \\u003cp\\u003e3\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c3\\\"\\u003e \\u003cp\\u003e43.67\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c4\\\"\\u003e \\u003cp\\u003e8.082\\u003c/p\\u003e \\u003c/td\\u003e \\u003c/tr\\u003e \\u003ctr\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c1\\\"\\u003e \\u003cp\\u003eGenerations per female in 28 days\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c2\\\"\\u003e \\u003cp\\u003e3\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c3\\\"\\u003e \\u003cp\\u003e6.67\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c4\\\"\\u003e \\u003cp\\u003e1.155\\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 \\u003cb\\u003eFigure\\u0026nbsp;1\\u003c/b\\u003e Frequency distribution of head capsule width measurements (mm) across larval instars I\\u0026ndash;IV of \\u003cem\\u003ePlutella xylostella\\u003c/em\\u003e (L.). Instar ranges: L1 (0.08\\u0026ndash;0.23 mm); L2 (0.23\\u0026ndash;0.38 mm); L3 (0.38\\u0026ndash;0.53 mm); L4 (0.53\\u0026ndash;0.68 mm). Measurements taken with a calibrated ocular micrometer (40\\u0026times;) from preserved exuviae. Dashed lines indicate instar boundaries. Conditions: 16.9\\u0026deg;C, 72.9% RH, 2,589 m a.s.l., Pamplona, Colombia\\u003c/p\\u003e \\u003cp\\u003e \\u003cb\\u003eFigure\\u0026nbsp;2\\u003c/b\\u003e (A) Duration (days\\u0026thinsp;\\u0026plusmn;\\u0026thinsp;SD) of developmental stages and (B) larval instar durations of \\u003cem\\u003ePlutella xylostella\\u003c/em\\u003e (L.) reared under mountain laboratory conditions (16.9\\u0026deg;C, 72.9% RH, 2,589 m a.s.l., Pamplona, Colombia). Diamonds (◆) indicate mean head capsule widths (secondary axis, right panel)\\u003c/p\\u003e \\u003cp\\u003e \\u003cb\\u003eFigure\\u0026nbsp;3\\u003c/b\\u003e Schematic life cycle diagram of \\u003cem\\u003ePlutella xylostella\\u003c/em\\u003e (L.) under mountain laboratory conditions (16.9\\u0026deg;C, 72.9% RH, 2,589 m a.s.l., Pamplona, Norte de Santander, Colombia). Duration means (days\\u0026thinsp;\\u0026plusmn;\\u0026thinsp;SD) and sample sizes are indicated for each stage. HCW mean head capsule width for each larval instar\\u003c/p\\u003e \\u003cp\\u003e \\u003cb\\u003eFigure\\u0026nbsp;4\\u003c/b\\u003e Head capsule width progression across larval instars of \\u003cem\\u003ePlutella xylostella\\u003c/em\\u003e (L.) on (A) linear scale with geometric fit (dashed line) and (B) logarithmic scale. Linear progression on the log scale validates Dyar's Rule. Values are mean\\u0026thinsp;\\u0026plusmn;\\u0026thinsp;SD; Dyar's ratios (\\u003cem\\u003ek\\u003c/em\\u003e) indicated between instar pairs. Conditions: 16.9\\u0026deg;C, 72.9% RH, 2,589 m a.s.l.\\u003c/p\\u003e \\u003cp\\u003e \\u003cb\\u003eFigure\\u0026nbsp;5\\u003c/b\\u003e Comparison of total life cycle duration (bars, left axis) and female fecundity (diamonds ◆, right axis) of \\u003cem\\u003ePlutella xylostella\\u003c/em\\u003e (L.) across studies conducted at different temperatures. Temperature (\\u0026deg;C) is shown above each bar. Data from: this study (16.9\\u0026deg;C, 2,589 m a.s.l.); Fern\\u0026aacute;ndez and \\u0026Aacute;lvarez (\\u003cspan citationid=\\\"CR5\\\" class=\\\"CitationRef\\\"\\u003e1998\\u003c/span\\u003e); Talekar and Shelton (\\u003cspan citationid=\\\"CR17\\\" class=\\\"CitationRef\\\"\\u003e1993\\u003c/span\\u003e); Jalali et al. (\\u003cspan citationid=\\\"CR11\\\" class=\\\"CitationRef\\\"\\u003e2011\\u003c/span\\u003e)\\u003c/p\\u003e \\u003c/div\\u003e\"},{\"header\":\"Discussion\",\"content\":\"\\u003cp\\u003eThe total life cycle of 57.06 days observed here is approximately 2\\u0026ndash;3\\u0026times; longer than life cycles recorded at 22\\u0026ndash;26\\u0026deg;C (19\\u0026ndash;38 days; Talekar and Shelton \\u003cspan citationid=\\\"CR17\\\" class=\\\"CitationRef\\\"\\u003e1993\\u003c/span\\u003e; Jalali et al. \\u003cspan citationid=\\\"CR11\\\" class=\\\"CitationRef\\\"\\u003e2011\\u003c/span\\u003e). This prolongation is consistent with the thermal biology of \\u003cem\\u003eP. xylostella\\u003c/em\\u003e, whose developmental lower threshold is estimated between 6.7\\u0026deg;C and 9.9\\u0026deg;C (Golizadeh et al. \\u003cspan citationid=\\\"CR10\\\" class=\\\"CitationRef\\\"\\u003e2007\\u003c/span\\u003e; Bahar et al. \\u003cspan citationid=\\\"CR1\\\" class=\\\"CitationRef\\\"\\u003e2014\\u003c/span\\u003e). At 16.9\\u0026deg;C, only a modest thermal excess is available per day, slowing all life stages proportionally (Ngowi et al. \\u003cspan citationid=\\\"CR14\\\" class=\\\"CitationRef\\\"\\u003e2017\\u003c/span\\u003e), as illustrated by the comparative data presented in Fig.\\u0026nbsp;5. This temperature-dependent developmental delay mirrors the pattern documented for other Lepidoptera at comparable high-altitude Andean sites: under nearly identical thermal conditions (17\\u0026deg;C, 2,589 m a.s.l.), \\u003cem\\u003eSpodoptera frugiperda\\u003c/em\\u003e showed total larval durations of 39\\u0026ndash;41 days compared with 14\\u0026ndash;22 days at 25\\u0026ndash;30\\u0026deg;C (Giraldo-Vanegas et al. \\u003cspan citationid=\\\"CR9\\\" class=\\\"CitationRef\\\"\\u003e2025\\u003c/span\\u003e), confirming that the thermal constraint imposed by altitude is a broadly acting constraint across Lepidoptera at this elevation.\\u003c/p\\u003e \\u003cp\\u003eThe confirmation of four larval instars via Dyar's Rule is consistent with all published reports for \\u003cem\\u003eP. xylostella\\u003c/em\\u003e (Talekar and Shelton \\u003cspan citationid=\\\"CR17\\\" class=\\\"CitationRef\\\"\\u003e1993\\u003c/span\\u003e; Jalali et al. \\u003cspan citationid=\\\"CR11\\\" class=\\\"CitationRef\\\"\\u003e2011\\u003c/span\\u003e; Philips et al. \\u003cspan citationid=\\\"CR15\\\" class=\\\"CitationRef\\\"\\u003e2014\\u003c/span\\u003e). The absolute head capsule widths recorded (L1\\u0026thinsp;=\\u0026thinsp;0.144 mm; L4\\u0026thinsp;=\\u0026thinsp;0.599 mm) closely match Fern\\u0026aacute;ndez and \\u0026Aacute;lvarez (\\u003cspan citationid=\\\"CR5\\\" class=\\\"CitationRef\\\"\\u003e1998\\u003c/span\\u003e) and Carvalho et al. (\\u003cspan citationid=\\\"CR3\\\" class=\\\"CitationRef\\\"\\u003e1999\\u003c/span\\u003e), suggesting that head capsule dimensions of \\u003cem\\u003eP. xylostella\\u003c/em\\u003e are conserved across a broad temperature range, while only developmental time differs\\u0026mdash;validating head capsule measurements as a temperature-independent diagnostic tool for instar identification in Andean populations. This stability is noteworthy in light of the instar number variability and increased head capsule width overlap reported for \\u003cem\\u003eS. frugiperda\\u003c/em\\u003e under similar high-mountain conditions, where a proportion of individuals produced supernumerary instars and growth ratios deviated from the classical Dyar's Rule expectation (Giraldo-Vanegas et al. \\u003cspan citationid=\\\"CR9\\\" class=\\\"CitationRef\\\"\\u003e2025\\u003c/span\\u003e). The contrasting response suggests that \\u003cem\\u003eP. xylostella\\u003c/em\\u003e possesses a more canalized developmental programme that resists low-temperature-induced plasticity, whereas polyphagous noctuids such as \\u003cem\\u003eS. frugiperda\\u003c/em\\u003e display greater phenotypic flexibility. From a methodological standpoint, these interspecific differences reinforce the recommendation that Dyar's Rule criteria should be validated locally for each target species at high altitude, rather than relying on growth parameters established under lowland or optimal thermal conditions.\\u003c/p\\u003e \\u003cp\\u003eFemale fecundity (43.67 eggs per female over 28 days) was markedly lower than the 150\\u0026ndash;300\\u0026thinsp;+\\u0026thinsp;eggs reported at optimal temperatures (Talekar and Shelton \\u003cspan citationid=\\\"CR17\\\" class=\\\"CitationRef\\\"\\u003e1993\\u003c/span\\u003e; Furlong et al. \\u003cspan citationid=\\\"CR6\\\" class=\\\"CitationRef\\\"\\u003e2013\\u003c/span\\u003e). Reduced fecundity combined with fewer potential generations within 28 days (6.67 vs. \\u0026gt;10 at 22\\u0026ndash;26\\u0026deg;C) suggests that the population growth potential of \\u003cem\\u003eP. xylostella\\u003c/em\\u003e is substantially curtailed at high altitude. Nevertheless, even this reduced reproductive output, combined with the absence of winter diapause at Pamplona's mild climate, means multiple overlapping generations persist year-round\\u0026mdash;explaining the chronic nature of DBM infestations in the region. Taken together with findings on \\u003cem\\u003eS. frugiperda\\u003c/em\\u003e thermal plasticity at the same site (Giraldo-Vanegas et al. \\u003cspan citationid=\\\"CR9\\\" class=\\\"CitationRef\\\"\\u003e2025\\u003c/span\\u003e), these results highlight high-mountain agroecosystems in the Colombian Andes as environments where pest management models must be locally calibrated: reduced thermal sums simultaneously suppress reproduction and extend development, altering the timing of susceptible larval stages and, consequently, the optimal windows for biological and chemical interventions.\\u003c/p\\u003e\"},{\"header\":\"Conclusions\",\"content\":\"\\u003cp\\u003e \\u003cem\\u003ePlutella xylostella\\u003c/em\\u003e completes four larval instars under high-altitude mountain conditions in Pamplona, Norte de Santander (2,589 m a.s.l., 16.9\\u0026deg;C), confirmed by Dyar's Rule. Head capsule width distributions were well-separated with minimal overlap, and growth ratios conformed to the canonical geometric progression, in contrast to the instar variability and supernumerary instars observed in \\u003cem\\u003eSpodoptera frugiperda\\u003c/em\\u003e under comparable high-mountain thermal conditions (Giraldo-Vanegas et al. \\u003cspan citationid=\\\"CR9\\\" class=\\\"CitationRef\\\"\\u003e2025\\u003c/span\\u003e). This interspecific difference suggests that \\u003cem\\u003eP. xylostella\\u003c/em\\u003e exhibits low developmental plasticity at high altitude, making head capsule measurements a reliable, temperature-independent tool for instar diagnosis in Andean populations. The total life cycle of 57.06 days is approximately two to three times longer than at lower altitudes, owing to reduced thermal sum at this elevation. The extended developmental periods have practical implications for IPM program timing in Andean agroecosystems. These biological data provide a regional baseline for developing accurate population models and sustainable management strategies for \\u003cem\\u003eP. xylostella\\u003c/em\\u003e in Colombian Andean \\u003cem\\u003eBrassicaceae\\u003c/em\\u003e production.\\u003c/p\\u003e\"},{\"header\":\"Declarations\",\"content\":\"\\u003ch2\\u003eCompeting interests\\u003c/h2\\u003e\\n\\u003cp\\u003eThe author declares no competing interests.\\u003c/p\\u003e\\n\\u003cp\\u003e\\u003cstrong\\u003eEthics approval\\u003c/strong\\u003e\\u003c/p\\u003e\\n\\u003cp\\u003eThis research did not involve human participants, human data, or vertebrate animals requiring formal ethical approval.\\u003c/p\\u003e\\n\\u003ch2\\u003eFunding\\u003c/h2\\u003e\\n\\u003cp\\u003eThe author declares that no external funding was received for this study.\\u003c/p\\u003e\\n\\u003cp\\u003e\\u003cstrong\\u003eAuthor Contribution\\u0026nbsp;Statement:\\u003c/strong\\u003e HGV conceived and designed the research, conducted all experiments, collected and analyzed data, and wrote the manuscript.\\u003c/p\\u003e\\n\\u003ch2\\u003eAcknowledgments\\u003c/h2\\u003e\\n\\u003cp\\u003eThe author thanks CISVEB staff and the Agronomy Engineering Program, Universidad de Pamplona, for technical and logistical support.\\u003c/p\\u003e\\n\\u003ch2\\u003eData availability\\u003c/h2\\u003e\\n\\u003cp\\u003eThe data supporting the findings of this study are available from the corresponding author upon reasonable request.\\u003c/p\\u003e\"},{\"header\":\"References\",\"content\":\"\\u003col\\u003e\\u003cli\\u003e\\u003cspan\\u003eBahar MH, Soroka JJ, Grenkow L, Dosdall LM (2014) New threshold temperatures for the development of a North American diamondback moth (Lepidoptera: Plutellidae) population and its larval parasitoid, \\u003cem\\u003eDiadegma insulare\\u003c/em\\u003e (Hymenoptera: Ichneumonidae). Environ Entomol 43(6):1443\\u0026ndash;1452. \\u003cspan class=\\\"ExternalRef\\\"\\u003e\\u003cspan class=\\\"RefSource\\\"\\u003ehttps://doi.org/10.1603/EN14055\\u003c/span\\u003e\\u003cspan address=\\\"10.1603/EN14055\\\" targettype=\\\"DOI\\\" class=\\\"RefTarget\\\"\\u003e\\u003c/span\\u003e\\u003c/span\\u003e\\u003c/span\\u003e\\u003c/li\\u003e \\u003cli\\u003e\\u003cspan\\u003eBirch LC (1948) The intrinsic rate of natural increase of an insect population. J Anim Ecol 17(1):15\\u0026ndash;26. \\u003cspan class=\\\"ExternalRef\\\"\\u003e\\u003cspan class=\\\"RefSource\\\"\\u003ehttps://doi.org/10.2307/1605\\u003c/span\\u003e\\u003cspan address=\\\"10.2307/1605\\\" targettype=\\\"DOI\\\" class=\\\"RefTarget\\\"\\u003e\\u003c/span\\u003e\\u003c/span\\u003e\\u003c/span\\u003e\\u003c/li\\u003e \\u003cli\\u003e\\u003cspan\\u003eCarvalho CN, Filho MM, Picanco M (1999) Determina\\u0026ccedil;\\u0026atilde;o do n\\u0026uacute;mero de \\u0026iacute;nstares larvais em \\u003cem\\u003ePlutella xylostella\\u003c/em\\u003e (L.) (Lepidoptera: Plutellidae). Acta Sci 21(2):331\\u0026ndash;335\\u003c/span\\u003e\\u003c/li\\u003e \\u003cli\\u003e\\u003cspan\\u003eDyar HG (1890) The number of molts of lepidopterous larvae. Psyche J Entomol 5(175\\u0026ndash;176):420\\u0026ndash;422. \\u003cspan class=\\\"ExternalRef\\\"\\u003e\\u003cspan class=\\\"RefSource\\\"\\u003ehttps://doi.org/10.1155/1890/23634\\u003c/span\\u003e\\u003cspan address=\\\"10.1155/1890/23634\\\" targettype=\\\"DOI\\\" class=\\\"RefTarget\\\"\\u003e\\u003c/span\\u003e\\u003c/span\\u003e\\u003c/span\\u003e\\u003c/li\\u003e \\u003cli\\u003e\\u003cspan\\u003eFern\\u0026aacute;ndez AS, \\u0026Aacute;lvarez C (1998) Biolog\\u0026iacute;a de \\u003cem\\u003ePlutella xylostella\\u003c/em\\u003e (L.) (Lepidoptera: Plutellidae), polilla del repollo (\\u003cem\\u003eBrassica oleracea\\u003c/em\\u003e L.) en condiciones de laboratorio. Agron Trop 38(4\\u0026ndash;6):17\\u0026ndash;28\\u003c/span\\u003e\\u003c/li\\u003e \\u003cli\\u003e\\u003cspan\\u003eFurlong MJ, Wright DJ, Dosdall LM (2013) Diamondback moth ecology and management: problems, progress, and prospects. Annu Rev Entomol 58:517\\u0026ndash;541. \\u003cspan class=\\\"ExternalRef\\\"\\u003e\\u003cspan class=\\\"RefSource\\\"\\u003ehttps://doi.org/10.1146/annurev-ento-120811-153605\\u003c/span\\u003e\\u003cspan address=\\\"10.1146/annurev-ento-120811-153605\\\" targettype=\\\"DOI\\\" class=\\\"RefTarget\\\"\\u003e\\u003c/span\\u003e\\u003c/span\\u003e\\u003c/span\\u003e\\u003c/li\\u003e \\u003cli\\u003e\\u003cspan\\u003eGaines JC, Campbell FL (1935) Dyar's rule as related to the number of instars of the corn earworm, \\u003cem\\u003eHeliothis obsoleta\\u003c/em\\u003e (Fab). Ann Entomol Soc Am 28(4):445\\u0026ndash;461. \\u003cspan class=\\\"ExternalRef\\\"\\u003e\\u003cspan class=\\\"RefSource\\\"\\u003ehttps://doi.org/10.1093/aesa/28.4.445\\u003c/span\\u003e\\u003cspan address=\\\"10.1093/aesa/28.4.445\\\" targettype=\\\"DOI\\\" class=\\\"RefTarget\\\"\\u003e\\u003c/span\\u003e\\u003c/span\\u003e\\u003c/span\\u003e\\u003c/li\\u003e \\u003cli\\u003e\\u003cspan\\u003eGarc\\u0026iacute;a-Caicedo M, Giraldo-Vanegas H, Ochoa A (2012) Ciclo de vida de \\u003cem\\u003eMetamasius dimidiatipennis\\u003c/em\\u003e Champeon (Coleoptera: Curculionidae) en condiciones de laboratorio. Agron Trop 62(1\\u0026ndash;4):69\\u0026ndash;75\\u003c/span\\u003e\\u003c/li\\u003e \\u003cli\\u003e\\u003cspan\\u003eGiraldo-Vanegas H, N\\u0026uacute;\\u0026ntilde;ez-Garc\\u0026iacute;a SN, Vel\\u0026aacute;squez-L\\u0026oacute;pez SM (2025) Influence of altitude on larval instar determination of \\u003cem\\u003eSpodoptera frugiperda\\u003c/em\\u003e (Lepidoptera: Noctuidae) under high-mountain laboratory conditions. \\u003cspan class=\\\"ExternalRef\\\"\\u003e\\u003cspan class=\\\"RefSource\\\"\\u003ehttps://doi.org/10.21203/rs.3.rs-8876098/v1\\u003c/span\\u003e\\u003cspan address=\\\"10.21203/rs.3.rs-8876098/v1\\\" targettype=\\\"DOI\\\" class=\\\"RefTarget\\\"\\u003e\\u003c/span\\u003e\\u003c/span\\u003e. Preprint\\u003c/span\\u003e\\u003c/li\\u003e \\u003cli\\u003e\\u003cspan\\u003eGolizadeh A, Kamali K, Fathipour Y, Abbasipour H (2007) Temperature-dependent development of diamondback moth, \\u003cem\\u003ePlutella xylostella\\u003c/em\\u003e (Lepidoptera: Plutellidae) on two Brassicaceous host plants. Insect Sci 14(4):309\\u0026ndash;316. \\u003cspan class=\\\"ExternalRef\\\"\\u003e\\u003cspan class=\\\"RefSource\\\"\\u003ehttps://doi.org/10.1111/j.1744-7917.2007.00153.x\\u003c/span\\u003e\\u003cspan address=\\\"10.1111/j.1744-7917.2007.00153.x\\\" targettype=\\\"DOI\\\" class=\\\"RefTarget\\\"\\u003e\\u003c/span\\u003e\\u003c/span\\u003e\\u003c/span\\u003e\\u003c/li\\u003e \\u003cli\\u003e\\u003cspan\\u003eJalali MA, Tirry L, Arbabi M, De Clercq P (2011) Biological study of \\u003cem\\u003ePlutella xylostella\\u003c/em\\u003e (L.) (Lep: Plutellidae) and its endoparasitoid, \\u003cem\\u003eCotesia vestalis\\u003c/em\\u003e (Haliday) (Hym: Braconidae) under laboratory conditions. Pak J Biol Sci 14(18):840\\u0026ndash;848. \\u003cspan class=\\\"ExternalRef\\\"\\u003e\\u003cspan class=\\\"RefSource\\\"\\u003ehttps://doi.org/10.3923/pjbs.2011.840.848\\u003c/span\\u003e\\u003cspan address=\\\"10.3923/pjbs.2011.840.848\\\" targettype=\\\"DOI\\\" class=\\\"RefTarget\\\"\\u003e\\u003c/span\\u003e\\u003c/span\\u003e\\u003c/span\\u003e\\u003c/li\\u003e \\u003cli\\u003e\\u003cspan\\u003eMacharia I, L\\u0026ouml;hr B, De Groote H (2005) Assessing the potential impact of biological control of \\u003cem\\u003ePlutella xylostella\\u003c/em\\u003e in cabbage production in Kenya. Crop Prot 24(11):981\\u0026ndash;989. \\u003cspan class=\\\"ExternalRef\\\"\\u003e\\u003cspan class=\\\"RefSource\\\"\\u003ehttps://doi.org/10.1016/j.cropro.2005.01.012\\u003c/span\\u003e\\u003cspan address=\\\"10.1016/j.cropro.2005.01.012\\\" targettype=\\\"DOI\\\" class=\\\"RefTarget\\\"\\u003e\\u003c/span\\u003e\\u003c/span\\u003e\\u003c/span\\u003e\\u003c/li\\u003e \\u003cli\\u003e\\u003cspan\\u003eMinisterio de Agricultura y Desarrollo Rural (2022) Agronet: Estad\\u0026iacute;sticas agropecuarias. Gobierno de Colombia. \\u003cspan class=\\\"ExternalRef\\\"\\u003e\\u003cspan class=\\\"RefSource\\\"\\u003ehttps://www.agronet.gov.co\\u003c/span\\u003e\\u003cspan address=\\\"https://www.agronet.gov.co\\\" targettype=\\\"URL\\\" class=\\\"RefTarget\\\"\\u003e\\u003c/span\\u003e\\u003c/span\\u003e\\u003c/span\\u003e\\u003c/li\\u003e \\u003cli\\u003e\\u003cspan\\u003eNgowi BV, Tonnang HEZ, Mwangi EM, Johansson T, Ambale J, Ndegwa PN, Subramanian S (2017) Temperature-dependent phenology of \\u003cem\\u003ePlutella xylostella\\u003c/em\\u003e (Lepidoptera: Plutellidae): simulation and visualization along the Eastern Afromontane. PLoS ONE 12(3):e0173590. \\u003cspan class=\\\"ExternalRef\\\"\\u003e\\u003cspan class=\\\"RefSource\\\"\\u003ehttps://doi.org/10.1371/journal.pone.0173590\\u003c/span\\u003e\\u003cspan address=\\\"10.1371/journal.pone.0173590\\\" targettype=\\\"DOI\\\" class=\\\"RefTarget\\\"\\u003e\\u003c/span\\u003e\\u003c/span\\u003e\\u003c/span\\u003e\\u003c/li\\u003e \\u003cli\\u003e\\u003cspan\\u003ePhilips CR, Fu Z, Kuhar TP, Shelton AM, Cordero RJ (2014) Natural history, ecology, and management of diamondback moth (Lepidoptera: Plutellidae). J Integr Pest Manag 5(3):1\\u0026ndash;12. \\u003cspan class=\\\"ExternalRef\\\"\\u003e\\u003cspan class=\\\"RefSource\\\"\\u003ehttps://doi.org/10.1603/IPM14008\\u003c/span\\u003e\\u003cspan address=\\\"10.1603/IPM14008\\\" targettype=\\\"DOI\\\" class=\\\"RefTarget\\\"\\u003e\\u003c/span\\u003e\\u003c/span\\u003e\\u003c/span\\u003e\\u003c/li\\u003e \\u003cli\\u003e\\u003cspan\\u003eR Core Team (2024) R: A language and environment for statistical computing (Version 4.4.0). R Foundation for Statistical Computing. \\u003cspan class=\\\"ExternalRef\\\"\\u003e\\u003cspan class=\\\"RefSource\\\"\\u003ehttps://www.R-project.org\\u003c/span\\u003e\\u003cspan address=\\\"https://www.R-project.org\\\" targettype=\\\"URL\\\" class=\\\"RefTarget\\\"\\u003e\\u003c/span\\u003e\\u003c/span\\u003e\\u003c/span\\u003e\\u003c/li\\u003e \\u003cli\\u003e\\u003cspan\\u003eTalekar NS, Shelton AM (1993) Biology, ecology, and management of the diamondback moth. Annu Rev Entomol 38:275\\u0026ndash;301. \\u003cspan class=\\\"ExternalRef\\\"\\u003e\\u003cspan class=\\\"RefSource\\\"\\u003ehttps://doi.org/10.1146/annurev.en.38.010193.001423\\u003c/span\\u003e\\u003cspan address=\\\"10.1146/annurev.en.38.010193.001423\\\" 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\":true,\"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\":\"info@researchsquare.com\",\"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\":\"diamondback moth, Brassicaceae, larval instars, Dyar's Rule, high-altitude agroecosystem, integrated pest management\",\"lastPublishedDoi\":\"10.21203/rs.3.rs-9534424/v1\",\"lastPublishedDoiUrl\":\"https://doi.org/10.21203/rs.3.rs-9534424/v1\",\"license\":{\"name\":\"CC BY 4.0\",\"url\":\"https://creativecommons.org/licenses/by/4.0/\"},\"manuscriptAbstract\":\"\\u003cp\\u003eThe diamondback moth, \\u003cem\\u003ePlutella xylostella\\u003c/em\\u003e (Linnaeus, 1758) (Lepidoptera: Plutellidae), is one of the most economically damaging insect pests of cruciferous crops worldwide. This study characterized the biology and determined the number of larval instars of \\u003cem\\u003eP. xylostella\\u003c/em\\u003e under controlled mountain laboratory conditions at 2,589 m a.s.l., mean temperature 16.9 ± 0.4°C, relative humidity 72.9 ± 3.1%, and dew point 12.1°C, using cabbage (\\u003cem\\u003eBrassica oleracea\\u003c/em\\u003e L. var. \\u003cem\\u003ecapitata\\u003c/em\\u003e) as rearing host, at the Centro de Investigación en Sanidad Vegetal y Bioinsumos (CISVEB), Pamplona, Norte de Santander, Colombia. The total life cycle lasted 57.06 days (range 33–78 days): egg 9.11 ± 1.242 days; total larval period 19.54 ± 2.620 days; pupal stage 9.93 ± 1.698 days; adult longevity 18.48 ± 5.124 days. Four larval instars were confirmed by Dyar's Rule, with mean head capsule widths of 0.144, 0.253, 0.405, and 0.599 mm (Dyar's ratio mean = 1.61). Mean female fecundity was 43.67 eggs per female over 28 days. Extended developmental durations relative to warmer-climate studies are attributed to reduced thermal sum at high altitude. These data provide a biological baseline for integrated pest management (IPM) programs in Andean \\u003cem\\u003eBrassicaceae\\u003c/em\\u003e production.\\u003c/p\\u003e\",\"manuscriptTitle\":\"Biology and Determination of Larval Instars of Plutella xylostella(Linnaeus, 1758) (Lepidoptera: Plutellidae) Under High-Altitude Mountain Laboratory Conditions in the Colombian Andes\",\"msid\":\"\",\"msnumber\":\"\",\"nonDraftVersions\":[{\"code\":1,\"date\":\"2026-04-28 10:28:31\",\"doi\":\"10.21203/rs.3.rs-9534424/v1\",\"editorialEvents\":[{\"type\":\"communityComments\",\"content\":0}],\"status\":\"published\",\"journal\":{\"display\":true,\"email\":\"info@researchsquare.com\",\"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\":\"99621bfd-a944-49a4-8ab6-67b96e24cfda\",\"owner\":[],\"postedDate\":\"April 28th, 2026\",\"published\":true,\"recentEditorialEvents\":[],\"rejectedJournal\":[],\"revision\":\"\",\"amendment\":\"\",\"status\":\"posted\",\"subjectAreas\":[{\"id\":67035494,\"name\":\"Agronomy\"}],\"tags\":[],\"updatedAt\":\"2026-04-28T10:28:31+00:00\",\"versionOfRecord\":[],\"versionCreatedAt\":\"2026-04-28 10:28:31\",\"video\":\"\",\"vorDoi\":\"\",\"vorDoiUrl\":\"\",\"workflowStages\":[]},\"version\":\"v1\",\"identity\":\"rs-9534424\",\"journalConfig\":\"researchsquare\"},\"__N_SSP\":true},\"page\":\"/article/[identity]/[[...version]]\",\"query\":{\"redirect\":\"/article/rs-9534424\",\"identity\":\"rs-9534424\",\"version\":[\"v1\"]},\"buildId\":\"XKTyCvWXoU3ODBz1xrDgd\",\"isFallback\":false,\"isExperimentalCompile\":false,\"dynamicIds\":[84888],\"gssp\":true,\"scriptLoader\":[]}","source_license":"CC-BY-4.0","license_restricted":false}