Diurnal activity patterns of Platycheirus hoverflies (Diptera: Syrphidae)

Diurnal activity patterns of Platycheirus hoverflies (Diptera: Syrphidae) | 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 Diurnal activity patterns of Platycheirus hoverflies (Diptera: Syrphidae) Aram Afrasiaw Ahmed Jaf, Emad Dawood Abbas Kaky, Francis Gilbert This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-8790774/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 Hoverflies are important plant pollinators which frequently visit flowers of many kinds of plant species. Although some aspects of the Syrphidae are well studied, the environmental conditions, foraging behaviours and activity rhythms of species within genera need further study in an evolutionary context. We considered the temporal activity rhythms of Platycheirus species to environmental factors such as ambient temperature and Relative Humidity (RH). Platycheirus activity depended mainly on temperature, and the individual species responded differently: the optimum temperature for achieving activity was between 13–23°C. The proportion of active individuals increased as the morning progressed, peaking before noon, indicating a unimodal activity pattern. Flight behaviour correlated negatively with temperature. Most observations fell between 50% − 80% RH. Males and females were similar in handling times on flowers, taking nectar and pollen, as well as the kinds of flower used. Handling times in the morning were longer than in the afternoon. Foraging speed not constrained phylogenetically (i.e species spent different times for foraging). Understanding behavioural responses to microclimate is a necessary component of insect adaptations to their environment. Syrphidae Flower flies Periodic activity foraging behaviours environmental factors Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 1. Introduction The diurnal activity pattern of insects depends considerably on various abiotic environmental conditions such as ambient temperature, light intensity, wind velocity, cloud cover and time of the day, mediated largely through their effects on body temperature (Williams, 1959 ; Maier and Waldbauer, 1979 ; Willmer, 1983 ; Gilbert, 1985 ; Hövemeyer, 1995 ). Activity patterns are part of a suite of adaptive behaviours related directly to resource availability, mating success and reducing competition (Bell, 1990 ). Ambient temperature has paramount importance for insect activity, particularly foraging behaviour, because only a few taxa are endothermic, able to maintain their body temperature and warm themselves (Willmer and Unwin, 1981 ; Sanborn et al., 1995 ). Most use elevated air temperature or solar basking at flowers to achieve the thoracic temperatures conducive to flight, and foraging activities are therefore constrained (Herrera, 1990 ). A number of studies have investigated insect responses to environmental factors, and provided details of how such factors affect insect activity rhythms. In general, most of the results show that activities such as flying and feeding increase as temperature increases up to a threshold, above which any additional increase in temperature causes a decline in activity (Digby, 1955 ; Taylor, 1963 ; Heinrich and Pantle, 1975 ; Maier and Waldbauer, 1979 ; Willmer, 1983 ; Gilbert, 1985 ; Willmer and Stone, 2004 ). Diurnal activity patterns are therefore the norm in most insects in their natural habitat. Thus foraging behaviour and flower visitation rates appear to have a positive correlation with light intensity and ambient temperature (Willmer, 1983 , Boyle-Makowski and Philogene, 1985 ). The effects of different microclimatic conditions on the diurnal activity patterns of syrphids have been investigated a number of times (e.g. Kikuchi, 1965 ; Nielson, 1966; Maier and Waldbauer, 1979 ; Gilbert, 1985 ). There is evidence that overheating may be an issue: some species prefer shaded places to avoid overheating and excessive water loss by direct sunlight, especially during the middle of hot days. Insects able to forage at flowers during the warmest parts of the day exhibit different traits from those foraging earlier or later: they are smaller, more pilose and lighter-coloured, often with reflective metallic colours (Willmer and Unwin, 1981 ; Willmer, 1983 , Gilbert, 1985 ). These traits all promote decreases in the temperature excess of the thorax, enabling such species to forage at the mid-day whilst avoiding excessive water loss and overheating (Willmer, 1983 , Ssymank et al., 2008 ). In contrast, many insect species show a decline in activity during midday which decreases the rate of flower visits (Maier and Waldbauer, 1979 ). These tend to be relatively large, dark-coloured species, traits which enable them to gain and maintain their body temperature at low ambient temperatures, and hence are able to fly early and late in the day, gaining access to rich nectar and pollen rewards, a particular advantage in the cool days of spring (Willmer and Unwin, 1981 ; Gilbert, 1985 ). For example, large dark milesiine syrphids are early visitors to flowers on warm mornings, but cannot do this on cool mornings (Maier and Waldbauer, 1979 ). Careful study can also even reveal differences between males and females of the same species. Hövemeyer ( 1995 ) found that the blackish male Cheilosia fasciata flew at lower temperatures than the olive-coloured females, perhaps due to the lower reflectance of the thoracic cuticle in the male. Recently, researchers have focused on the activity of hoverflies because of their double role in agroecosystems, providing important ecosystem services both as pollinators and potential biocontrol agents (Burgio and Sommaggio, 2007 ; D'Amen et al., 2013 ; Smit et al., 2017 ). The influence of the availability of pollen and nectar on diurnal rhythms has not been explored, apart from Maier and Waldbauer’s ( 1979 ) study of the behaviour of six milesiines in response to hygrothermal stress, food availability and mating success. The study of the diurnal activity patterns of several hoverfly species by Gilbert ( 1985 ) was testing the importance of body size and thermoregulation. All previous work has studied the commonest species regardless of evolutionary relationships. The present study focuses on all available species of a specific genus, Platycheirus Lepeletier and Serville, 1828. Their diurnal activity rhythms in the study area were considered in detail to show the influences of various abiotic factors on the level of activity, and to measure how foraging behaviour changes in response to ambient temperature, time of the day and flower types. The aim of this study is to examine the diurnal activity patterns of Platycheirus species and their relationship with climatic variables such as temperature, humidity, and light intensity. 2. Materials and Methods The fieldwork was conducted in the Attenborough Nature Reserve area (52°54'01.7"N 1°14'04.6"W) (Fig. 1 ), during May to early October in the year 2016 and May to August 2017, to record syrphid behaviour and activities. Data were collected through observations made along a census route (Pollard, 1977 ; Gilbert, 1985 ; Fischer et al., 1996 ) done one or two days every week depending on the weather. No census walks were conducted during periods of unfavourable weather (e.g. rainy or heavy wind days) which preclude hoverfly activity. The census walks usually began at 7:00 h (when individual hoverflies usually commence their activities) and normally ended when the activities of individual syrphids ceased after 17:00 h (all times are reported in British Standard Time (BST), 1h ahead of GMT). The census route was walked slowly and continuously at as constant a speed as possible, searching for hoverflies of the genus Platycheirus and their sister-group Melanostoma en route, concentrating on the flowers, herbaceous vegetation, and shrubs on both sides (Stubbs and Falk 2002 ). Each hoverfly seen and thought to be a species of Platycheirus or Melanostoma was closely observed for few seconds to investigate and recording the activity when first seen. During the census walks hoverfly activities were recorded as the height of each individual flying, their activities (flying or feeding) and resting (e.g. staying beneath plant leaves). Foraging behaviour was recorded for each Platycheirus individual seen visiting flowers. Their foraging bout was followed until they had visited five different individual flowers, for which visit durations were recorded and time spent shuttling between flowers calculated (Miñarro and Twizell, 2015 ). Sometimes it was difficult to assess visitation rate because some syrphids commonly completed their feeding bout after only one or two flowers, and then either stopped feeding (going to rest on the flower or on nearby leaves, usually to clean), or just flew away, to minimize this limitation, visitation rate was calculated only for individuals that remained within the observation area for a minimum observation period. A hand net and aspirator were used for capturing hoverflies (Leereveld et al., 1976 ; Petanidou et al., 2011 ). Captured individuals were then placed in a specific glass container, numbered and euthanized in the laboratory by freezing for further identification and diagnosis. Stubbs a Falk’s (2002) key was used for nomenclature of specimens. Weather conditions, represented by ambient temperature, wind speed and relative humidity (R.H.), were recorded immediately with each observation. A mercury thermometer was used for measuring temperature. When first seen, we recorded whether the individual was in direct sunlight or in shade. A psychrometer was used for measuring atmosphere relative humidity every hour during the days when flies were sampled (Maier and Waldbauer 1979 ). The data were combined with data from Gilbert's (1981) study from Cambridge with very similar methodology, in order to increase the number of species available. The data were transformed to the proportion of observations for each individual species performing specific activity to distinguish a number of species behaviour changes in relative to their environmental conditions (following Gilbert, 1985 ). As an index of the temperature response, the lowest temperature at which 50% of individuals are active was estimated from the plot of temperature vs. %active (see Fig. 3 a), and was taken as a species-specific characteristic. The overall percentage of individuals active in the shade was also taken to be a species-specific characteristic. All statistical analysis were implemented in R 3.4.0 environment (R development core team, 2017). 3. Results A total of 1842 specimens of hoverflies were collected, representing ten species (Table 1 ), eight Platycheirus and two Melanostoma . Combined numbers showed that specimens were seen in the morning much more abundantly than in the afternoon, accounting for about 60% (morning) and 40% (afternoon). Females were more common in the sample, accounting for about 65.5% (morning) and 59.3% (afternoon). The most dominant Platycheirus species by far was P. albimanus , accounting for about 55.5% of all Platycheirus individuals. Melanostoma scalare was just as common as P.albimanus : together these two species represented 70% of the sample. In contrast to P. albimanus , several species were rare, with only two observation for both P. angustatus and P. tarsalis . Our analysis focused on the seven most abundant species (Table 1 ). Table 1 Number of individuals of all species recorded during fieldwork. data from Nottingham data from Cambridge am pm am pm species m f m f total m f m f total Grand Total P. albimanus 23 41 50 70 184 52 72 75 86 285 469 P. peltatus 2 1 2 3 8 30 27 22 18 97 105 P. manicatus 4 0 0 0 4 2 32 22 42 98 102 P. clypeatus 2 1 1 0 4 16 52 14 14 96 100 P. scutatus 4 11 4 22 41 5 9 2 2 18 59 P. fulviventris 6 3 0 3 12 0 0 0 0 0 12 P. angustatus 1 0 0 0 1 0 1 0 0 1 2 P. tarsalis 0 0 2 0 2 0 0 0 0 0 2 M. scalare 39 74 18 46 177 157 311 51 109 628 805 M. mellinum 4 0 3 2 9 43 90 19 25 177 186 No species were observed active at dawn apart from M. scalare , a shade tolerant species whose activity commenced at 05:00 h (Fig. 2 ). The proportion of active individuals (flying or feeding) increased in all species as the morning progressed, usually commencing at about 7:00h and reaching a peak before noon at 11:00h. comprising about (60%-80%) of the total observations (Fig. 2 ). A slight reduction in activity was recorded during the early afternoon, corresponding with higher temperatures and lower relative humidity. A relatively constant 40% − 50% of observations for the most species were recorded between 12:00h and 13:00h, and then this proportion declined drastically thereafter at 15:00h. The two species P. peltatus and P. clypeatus shows a slightly rebound in their activity between 13:00 and 14:00 h (Fig. 2 ). All observations after 15:00h were specimens seen at rest. Pollen feeding was always during the morning, whereas most specimens were feeding on nectar during the early afternoon, especially on hot days. Because the length of time of the day varies substantially from spring to summer, activity is analyzed in relation to weather variables rather than time. The most favourable temperatures for most species were between 13–23°C (Fig. 3 ) except for P. albimanus and M. scalare , which commenced their activity at 12°C. Flight behaviour was correlated directly with temperature. During the course of the day, species did not fly until temperatures began to rise. As the temperature became high they flew relatively faster and shorter flights that were largely restricted to shaded regions. The height of the flights was negatively correlated with ambient temperature (Fig. 4 ). Above 20°C the active behaviours (flying or feeding) were limited to shaded regions or under cloudy conditions, whereas below 20°C flight was much more restricted to habitats with direct sunlight. The index of the temperature responses of the species (Fig. 3 , Table 2 ) showed only small differences, except perhaps for M.scalare being lower than other species. There was detectable phylogenetic signal in neither Pagel's λ (λ = 0.006, p = 0.91, n = 7) or Blomberg's K (K = 0.022, p = 0.81, n = 7). Table 2 The temperature at which 50% of the individual hoverflies were active (estimated from the graphs in Fig. 3 ). Species estimated temperature P. scutatus 13.3 P. albimanus 12.3 P. clypeatus 13.3 M. scalare 12.3 M. mellinum 14.0 P. manicatus 13.3 P. peltatus 14.3 In terms of relative humidity, the activities of most species fell in the range 50%-80% (Fig. 5 ), with the exception of M. scalare which remained active to 90% R.H. P. albimanus tended to feed on pollen at high R.H., and nectar at low R.H. (Fig. 6 ). The activities of most species declined (and resting behaviour increased) with increasing humidity, with nearly all activities ceasing above 90% R.H. (Fig. 5 ). The exceptions were P. albimanus and M. scalare , which remained active even at high R.H. The times spent to forage on five individual flowers were recorded for some of the Platycheirus and Melanostoma species seen visiting flowers for nectar or pollen (Table 2 ). Although tested with too few data, there was no overall difference in foraging times for pollens versus nectar (Wilcoxon signed rank statistic, W = 41.5, p = 0.18). There was an obvious pattern in that species spent more time to forage five flowers in the morning than later in the day (Fig. 8 ), which is clearly temperature-related. We used the means of these foraging speeds to estimating the level of phylogenetic signal. Although with few data, the results for both Pagel's (λ = 0.53, p = 0.58, n = 5) and Blomberg's (K = 0.81, p = 0.11, n = 5) methods suggest that this behavioural trait is not constrained phylogenetically. Moreover, when the proportion of active species were calculated under cloudy cover, the estimated phylogenetic signal results for both Pagel’s and Blomberg’s K were also non-significant (λ = 0.0066, p = 0.89, n = 8) and Blomberg's (K = 0.175, p = 0.454, n = 8), this suggest that species flew under cloud cover have no evolutionary relationships with the species common ancestor. 4. Discussion Insect diurnal activity rhythms are influenced by a number of environmental variables, but because of the presence of intercorrelations between them, caution must be taken when assessing the causes of the diurnal activity patterns (Miñarro and Twizell, 2015 ). The patterns of insect activity seen in nature is probably mainly determined by interactions between thermal balance and intrinsic diel rhythmicity, and body size has a great influence upon thermal balance (Wilmer, 1983; Gilbert, 1985 ). Different authors have investigated syrphid behaviours and their diurnal patterns. Lewis and Taylor ( 1965 ) recorded flight activity patterns for different species including hoverflies. Both Metasyrphus corolla and Episyrphus balteatus have their maximum activities soon after sunrise where as Melanostoma mellinum L. has been found visiting flowers before sunrise (Morse, 1981 ) and in the very early morning (Vlašánková et al., 2017 ). Rhingia mecyana was the most frequent flower visitor before and after noon (Vlašánková et al., 2017 ), and a peak near mid-morning was the pattern of some syrphids (Maier and Waldbauer, 1979 ). During the hot summer, some Mediterranean syrphids such as Eumerus and Merodon species are crepuscular (Ssymnak, unpublished, cited by Inouye et al., 2015 ), and Volucella vesicularia can only be collected in large numbers during its crepuscular flower visiting (Waldbauer, 1963 ). Bimodal diel periodicity can also be a feature in some syrphid flies, for instance, Scaeva pyrastri coming to artificial flowers in March (Willmer and Unwin 1981 ), caused by long-distance (up to 5 km) daily circulation between feeding and resting places. All these patterns are explicable in term of relation to microclimatic condition and foraging behaviours. The activity of Platycheirus species reached a peak around mid-morning, before noon, indicating a unimodal pattern of activity. This pattern could be explained in many ways. One possible explanation may be a reduction in competition with other species, since larger flies can be more vulnerable to direct insolation and higher midday temperatures, which may increase the risk of overheating and dehydration. (Willmer and Unwin 1981 ; Herrera, 1990 ). The prevalence of hot, dry conditions and greater availability of food in the morning is another explanation (D'Amen et al., 2013 ). However, some flies do not follow this pattern: for instance, Sarcophaga (Sarcophagidae) in Britain are capable of visiting flowers in the middle of the day even though they are rather large and blackish in colour (Willmer, 1982a ). Some other flies can be inactive during the warm periods of the day, such as Calliphora (Calliphoridae): even though they are metallic, they are unable to regulate their body temperature as efficiently as Sarcophaga species (Inouye et al., 2015 ). For small, dark-coloured flies, direct sunlight can be physiologically stressful while visiting flowers. They can take advantage of the local shade to lower their temperature excess, allowing them to visit flowers during the warmest part of the day (Willmer and Unwin, 1981 ). When insolation is low, the flower-visiting activity of small anthophilous flies decreases during the course of the day, only beginning to forage when the temperature rises: small flies can stay warm by foraging in sun-flecks (Rotheray and Gilbert, 2011 ). The observed temporal patterns of foraging activities can be explained by physiological constraints. For instance, the temperature at early morning and afternoon might only be appropriate for foraging for relativity non-reflective and large flies, with the mid-day being too warm for foraging (Inouye et al., 2015 ). This produces a bimodal pattern of activity, as shown for Syrphidae on Apiaceae flowers in Britain (Willmer 1983 ) and Lamiaceae flowers in Spain (Herrera, 1990 ). This pattern changes to unimodal activity on cool days (Willmer, 1982b ). Syrphid flies visit the flowers of many different plant species, and their visitation rate is mainly determined by activity levels. Herrera ( 1990 ) mentioned that the visitation rate relies on both flight time (the time spent flying between flowers) and handling time (the time spent extracting the rewards). Our results showed that Platycheirus spp. spent more time for foraging in the morning than they did late in the day, possibly an indication that overheating avoidance is more important than the availability of rewards. Wilmer (1983) mentioned this foraging pattern for flies on Tilia and Heracleum flowers, and this has been corroborated by other studies (e.g. Herrera, 1990 , who also indicated that fly activity rhythms do not reflect reward availability). Normally, northern temperate flowers produce nectar and pollen in the early morning, and the concentration and secretion of nectar vary through the course of the day in relation to humidity and temperature (Corbet et al., 1979 ; Goldberg, 2009 ). Flight can be energetically very expensive, and optimal foraging models predict that anthophiles should ensure that their foraging decisions lead to a net energy gain (Pyke, 1978 ). This pattern has been shown in hoverflies (Gilbert, 1985 ) by a significant negative correlation between individual syrphid thoracic volume and the percentage of time spent flying, while no similar correlations appeared with time spent on feeding or resting. Our analysis suggests that times of the day are important for interpreting Platycheirus behaviours in relation to microclimatic conditions, something well supported by the large literature on the ecology of hoverflies (Maier and Waldbauer, 1979 ; Gilbert, 1985 ; Hövemeyer, 1995 ; D’Amen et al., 2013). Generally, it is thought that morphological and physiological traits are more conservative than behavioural traits (Rheindt et al., 2004 ). By estimating the level of phylogenetic signal in times that species spent to forage on five different flower (Table 3 ), it was clearly appeared that foraging behaviour patterns was not constrained phylogenetically, this was supported by literature that behavioural traits are evolutionary more labile (Blomberg et al., 2003 ; Gittleman et al., 1996 ; Rheindt et al., 2004 ). Moreover, the phylogenetic inertia was also lack when we estimated it in the ecological characters (i.e. temperature at which 50% of the individual commenced their activity), again this was supported by presence of insignificant level of phylogenetic signal in responses of different species to temperature. Table 3 Average visit duration time spent for each species to forage on five different kinds of flowers. Species Kind of flower Kind of food Average time spent/min. Sex P. albimanus Ranunculus pollen 4:40 M Ranunculus nectar 3:37 F Cruciferae pollen 5:37 M Rubus fruticosus pollen 2.40 M Rubus fruticosus pollen 5:27 F Tanacetum parthenium pollen 3:21 M Crepis nectar 4:54 M Erodium pollen 4:11 F Apiaceae pollen 5:41 F Silene noctiflora nectar 5:26 M P. scutatus Ranunculus pollen 3:23 M Ranunculus pollen 2:25 F Geum urbanum pollen 3:41 F P. fulviventris Plantago lanceolata pollen 6:12 M P. tarsalis Erodium nectar 1:47 M M. scalare Agrostis tenuis pollen 11.23 M Taraxacum pollen 2:28 F Taraxacum pollen 8:24 M Erodium nectar 5:47 F Ranunculus pollen 9:47 F Ranunculus nectar 2:57 F Declarations Funding Information for Submitted Manuscript I would like to confirm that my PhD studies are financially supported by the Higher Committee for Education Development under grant number D1202023. The submitted manuscript represents part of the research conducted within the framework of this funded PhD project. The funding body provided financial support for my doctoral research, which includes the work presented in this paper. The funding organization had no involvement in the study design, data collection, analysis, interpretation of results, or the decision to submit the manuscript for publication. Author Contribution 1- Aram Afrasiaw Ahme Jaf wrote the main manuscript.2- Emad Dawood Abbas Kaky did the data analysis.3- Francis Gilbert review the manuscript and was my supervisor during achieving my PhD thesis. Acknowledgements We thank Jeff Skevington and Young Andrew for helping species identifications; Matthew Symonds for the first incredible review and comments on the paper. We also thank the Higher Committee for Education Development in Iraq (HCED) for achieving scholarship for student studying. References Bell W (1990). Searching behaviour patterns in insects. Annual Review of Entomology 35(1): 447–467. Blomberg S, Garland T, Ives A (2003). 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New Phytologist, 215(4): 1574–1581. Waldbauer G P (1963). Crepuscular flower visits of adult Volucella vesicularia Curran (Diptera, Syrphidae). Entomological News, 74: 135–137. Williams G (1959). Seasonal and diurnal activity of Carabidae, with particular reference to Nebria, Notiophilus and Feronia. Journal of Animal Ecology, 309–330. Willmer P G, Stone, G N (2004). Behavioural, ecological, and physiological determinants of the activity patterns of bees. Advances in the Study of Behaviour, 34: 347–466. Willmer P G, Unwin D M (1981). Field analyses of insect heat budgets: reflectance, size and heating rates. Oecologia, 50(2): 250–255. Willmer P G (1982a). Thermoregulatory mechanisms in Sarcophaga . Oecologia, 53(3): 382–385. Willmer P G (1982b). Hygrothermal determinants of insect activity patterns: the Diptera of water-lily leaves. Ecological Entomology, 7(2): 221–231. Willmer P G (1983). Thermal constraints on activity patterns in nectar-feeding insects. Ecological Entomology, 8(4): 455–469. Additional Declarations No competing interests reported. Cite Share Download PDF Status: Posted Version 1 posted You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-8790774","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":607692730,"identity":"208570b8-72e5-462d-9888-53b6078abdf4","order_by":0,"name":"Aram Afrasiaw Ahmed Jaf","email":"data:image/png;base64,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","orcid":"","institution":"University of Garmain","correspondingAuthor":true,"prefix":"","firstName":"Aram","middleName":"Afrasiaw Ahmed","lastName":"Jaf","suffix":""},{"id":607692732,"identity":"fd522b58-eb6f-4dc6-b1e9-e925296fe064","order_by":1,"name":"Emad Dawood Abbas Kaky","email":"","orcid":"","institution":"","correspondingAuthor":false,"prefix":"","firstName":"Emad","middleName":"Dawood Abbas","lastName":"Kaky","suffix":""},{"id":607692734,"identity":"31a2a044-c783-4308-a084-4680a382503c","order_by":2,"name":"Francis Gilbert","email":"","orcid":"","institution":"","correspondingAuthor":false,"prefix":"","firstName":"Francis","middleName":"","lastName":"Gilbert","suffix":""}],"badges":[],"createdAt":"2026-02-04 23:53:19","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-8790774/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-8790774/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":104884113,"identity":"0a039acc-5198-45ce-920d-8c256389a0cd","added_by":"auto","created_at":"2026-03-18 09:44:27","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":398174,"visible":true,"origin":"","legend":"\u003cp\u003e(a) Location of the study site in the United Kingdom; (b) Google Earth image of Attenborough Nature Centre and Reserve area where this study was carried out.\u003c/p\u003e","description":"","filename":"1.png","url":"https://assets-eu.researchsquare.com/files/rs-8790774/v1/661b0ec7afcb393b8f967a48.png"},{"id":104884142,"identity":"a841c61b-332b-4968-b752-57de304d9bc6","added_by":"auto","created_at":"2026-03-18 09:44:36","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":164916,"visible":true,"origin":"","legend":"\u003cp\u003ePercentage of individuals seen active at different times of the day (BST) of the seven most common species\u003c/p\u003e","description":"","filename":"2.png","url":"https://assets-eu.researchsquare.com/files/rs-8790774/v1/712b5b8a26be01604d20d1e1.png"},{"id":104884138,"identity":"0c572099-738b-41f8-bc1c-aa16185df644","added_by":"auto","created_at":"2026-03-18 09:44:34","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":192231,"visible":true,"origin":"","legend":"\u003cp\u003ePercentages of individuals seen resting at different ambient temperatures of the seven most common species\u003c/p\u003e","description":"","filename":"3.png","url":"https://assets-eu.researchsquare.com/files/rs-8790774/v1/e0c030673c66713c4adb1cba.png"},{"id":104884110,"identity":"3bb78d93-5316-4d47-83af-da2b3aff49a6","added_by":"auto","created_at":"2026-03-18 09:44:26","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":77655,"visible":true,"origin":"","legend":"\u003cp\u003eCorrelation between ambient temperature and height seen flying for \u003cem\u003ePlatycheirus\u003c/em\u003e \u003cem\u003ealbimanus\u003c/em\u003e, \u003cem\u003eP. scutatus\u003c/em\u003eand \u003cem\u003eMelanostoma\u003c/em\u003e species (r= -0.20, n= 134, p= 0.211).\u003c/p\u003e","description":"","filename":"4.png","url":"https://assets-eu.researchsquare.com/files/rs-8790774/v1/603293f53148beb60e2322fe.png"},{"id":104884135,"identity":"f3884f19-7548-4097-a899-c85b32609a35","added_by":"auto","created_at":"2026-03-18 09:44:32","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":172503,"visible":true,"origin":"","legend":"\u003cp\u003eThe percentage of observations of seven species seen resting at different relative humidities.\u003c/p\u003e","description":"","filename":"5.png","url":"https://assets-eu.researchsquare.com/files/rs-8790774/v1/57bc197033bfac429a0b3897.png"},{"id":104884136,"identity":"c58ae8b2-15f8-4729-a261-8197e431fd13","added_by":"auto","created_at":"2026-03-18 09:44:33","extension":"png","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":76950,"visible":true,"origin":"","legend":"\u003cp\u003eThe percentage of feeding \u003cem\u003eP.\u003c/em\u003e \u003cem\u003ealbimanus\u003c/em\u003e individuals feeding on pollen at different relative humidities; other feeding individuals were feeding on nectar.\u003c/p\u003e","description":"","filename":"6.png","url":"https://assets-eu.researchsquare.com/files/rs-8790774/v1/d2097437b752acd9fcb94466.png"},{"id":104884109,"identity":"d33b9d3e-09cb-4438-bca5-88faddf0b778","added_by":"auto","created_at":"2026-03-18 09:44:25","extension":"png","order_by":7,"title":"Figure 7","display":"","copyAsset":false,"role":"figure","size":60217,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eFigure 8. \u003c/strong\u003eCorrelation between the time required to feed on five flowers with the time of day (\u003cem\u003ePlatycheirus\u003c/em\u003e and \u003cem\u003eMelanostoma\u003c/em\u003e species combined) (r = -0.53, n = 24, p = 0.246).\u003c/p\u003e","description":"","filename":"7.png","url":"https://assets-eu.researchsquare.com/files/rs-8790774/v1/ef4c24e82834979747daf19c.png"},{"id":106332166,"identity":"4e71ef3e-7640-4872-aa39-d043e8b69ed0","added_by":"auto","created_at":"2026-04-07 14:13:22","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1769338,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-8790774/v1/3455cad8-1a98-4178-97ca-7ae01175ba2f.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Diurnal activity patterns of Platycheirus hoverflies (Diptera: Syrphidae)","fulltext":[{"header":"1. Introduction","content":"\u003cp\u003eThe diurnal activity pattern of insects depends considerably on various abiotic environmental conditions such as ambient temperature, light intensity, wind velocity, cloud cover and time of the day, mediated largely through their effects on body temperature (Williams, \u003cspan citationid=\"CR38\" class=\"CitationRef\"\u003e1959\u003c/span\u003e; Maier and Waldbauer, \u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e1979\u003c/span\u003e; Willmer, \u003cspan citationid=\"CR43\" class=\"CitationRef\"\u003e1983\u003c/span\u003e; Gilbert, \u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e1985\u003c/span\u003e; H\u0026ouml;vemeyer, \u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e1995\u003c/span\u003e). Activity patterns are part of a suite of adaptive behaviours related directly to resource availability, mating success and reducing competition (Bell, \u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1990\u003c/span\u003e). Ambient temperature has paramount importance for insect activity, particularly foraging behaviour, because only a few taxa are endothermic, able to maintain their body temperature and warm themselves (Willmer and Unwin, \u003cspan citationid=\"CR40\" class=\"CitationRef\"\u003e1981\u003c/span\u003e; Sanborn et al., \u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e1995\u003c/span\u003e). Most use elevated air temperature or solar basking at flowers to achieve the thoracic temperatures conducive to flight, and foraging activities are therefore constrained (Herrera, \u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e1990\u003c/span\u003e). A number of studies have investigated insect responses to environmental factors, and provided details of how such factors affect insect activity rhythms. In general, most of the results show that activities such as flying and feeding increase as temperature increases up to a threshold, above which any additional increase in temperature causes a decline in activity (Digby, \u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e1955\u003c/span\u003e; Taylor, \u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e1963\u003c/span\u003e; Heinrich and Pantle, \u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e1975\u003c/span\u003e; Maier and Waldbauer, \u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e1979\u003c/span\u003e; Willmer, \u003cspan citationid=\"CR43\" class=\"CitationRef\"\u003e1983\u003c/span\u003e; Gilbert, \u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e1985\u003c/span\u003e; Willmer and Stone, \u003cspan citationid=\"CR39\" class=\"CitationRef\"\u003e2004\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eDiurnal activity patterns are therefore the norm in most insects in their natural habitat. Thus foraging behaviour and flower visitation rates appear to have a positive correlation with light intensity and ambient temperature (Willmer, \u003cspan citationid=\"CR43\" class=\"CitationRef\"\u003e1983\u003c/span\u003e, Boyle-Makowski and Philogene, \u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e1985\u003c/span\u003e). The effects of different microclimatic conditions on the diurnal activity patterns of syrphids have been investigated a number of times (e.g. Kikuchi, \u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e1965\u003c/span\u003e; Nielson, 1966; Maier and Waldbauer, \u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e1979\u003c/span\u003e; Gilbert, \u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e1985\u003c/span\u003e). There is evidence that overheating may be an issue: some species prefer shaded places to avoid overheating and excessive water loss by direct sunlight, especially during the middle of hot days. Insects able to forage at flowers during the warmest parts of the day exhibit different traits from those foraging earlier or later: they are smaller, more pilose and lighter-coloured, often with reflective metallic colours (Willmer and Unwin, \u003cspan citationid=\"CR40\" class=\"CitationRef\"\u003e1981\u003c/span\u003e; Willmer, \u003cspan citationid=\"CR43\" class=\"CitationRef\"\u003e1983\u003c/span\u003e, Gilbert, \u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e1985\u003c/span\u003e). These traits all promote decreases in the temperature excess of the thorax, enabling such species to forage at the mid-day whilst avoiding excessive water loss and overheating (Willmer, \u003cspan citationid=\"CR43\" class=\"CitationRef\"\u003e1983\u003c/span\u003e, Ssymank et al., \u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e2008\u003c/span\u003e). In contrast, many insect species show a decline in activity during midday which decreases the rate of flower visits (Maier and Waldbauer, \u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e1979\u003c/span\u003e). These tend to be relatively large, dark-coloured species, traits which enable them to gain and maintain their body temperature at low ambient temperatures, and hence are able to fly early and late in the day, gaining access to rich nectar and pollen rewards, a particular advantage in the cool days of spring (Willmer and Unwin, \u003cspan citationid=\"CR40\" class=\"CitationRef\"\u003e1981\u003c/span\u003e; Gilbert, \u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e1985\u003c/span\u003e). For example, large dark milesiine syrphids are early visitors to flowers on warm mornings, but cannot do this on cool mornings (Maier and Waldbauer, \u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e1979\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eCareful study can also even reveal differences between males and females of the same species. H\u0026ouml;vemeyer (\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e1995\u003c/span\u003e) found that the blackish male \u003cem\u003eCheilosia fasciata\u003c/em\u003e flew at lower temperatures than the olive-coloured females, perhaps due to the lower reflectance of the thoracic cuticle in the male.\u003c/p\u003e \u003cp\u003eRecently, researchers have focused on the activity of hoverflies because of their double role in agroecosystems, providing important ecosystem services both as pollinators and potential biocontrol agents (Burgio and Sommaggio, \u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e2007\u003c/span\u003e; D'Amen et al., \u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e2013\u003c/span\u003e; Smit et al., \u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e2017\u003c/span\u003e). The influence of the availability of pollen and nectar on diurnal rhythms has not been explored, apart from Maier and Waldbauer\u0026rsquo;s (\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e1979\u003c/span\u003e) study of the behaviour of six milesiines in response to hygrothermal stress, food availability and mating success. The study of the diurnal activity patterns of several hoverfly species by Gilbert (\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e1985\u003c/span\u003e) was testing the importance of body size and thermoregulation.\u003c/p\u003e \u003cp\u003eAll previous work has studied the commonest species regardless of evolutionary relationships. The present study focuses on all available species of a specific genus, \u003cem\u003ePlatycheirus\u003c/em\u003e Lepeletier and Serville, 1828. Their diurnal activity rhythms in the study area were considered in detail to show the influences of various abiotic factors on the level of activity, and to measure how foraging behaviour changes in response to ambient temperature, time of the day and flower types. The aim of this study is to examine the diurnal activity patterns of \u003cem\u003ePlatycheirus\u003c/em\u003e species and their relationship with climatic variables such as temperature, humidity, and light intensity.\u003c/p\u003e"},{"header":"2. Materials and Methods","content":"\u003cp\u003eThe fieldwork was conducted in the Attenborough Nature Reserve area (52\u0026deg;54'01.7\"N 1\u0026deg;14'04.6\"W) (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e), during May to early October in the year 2016 and May to August 2017, to record syrphid behaviour and activities. Data were collected through observations made along a census route (Pollard, \u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e1977\u003c/span\u003e; Gilbert, \u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e1985\u003c/span\u003e; Fischer et al., \u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e1996\u003c/span\u003e) done one or two days every week depending on the weather. No census walks were conducted during periods of unfavourable weather (e.g. rainy or heavy wind days) which preclude hoverfly activity. The census walks usually began at 7:00 h (when individual hoverflies usually commence their activities) and normally ended when the activities of individual syrphids ceased after 17:00 h (all times are reported in British Standard Time (BST), 1h ahead of GMT).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eThe census route was walked slowly and continuously at as constant a speed as possible, searching for hoverflies of the genus \u003cem\u003ePlatycheirus\u003c/em\u003e and their sister-group \u003cem\u003eMelanostoma\u003c/em\u003e en route, concentrating on the flowers, herbaceous vegetation, and shrubs on both sides (Stubbs and Falk \u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e2002\u003c/span\u003e). Each hoverfly seen and thought to be a species of \u003cem\u003ePlatycheirus\u003c/em\u003e or \u003cem\u003eMelanostoma\u003c/em\u003e was closely observed for few seconds to investigate and recording the activity when first seen. During the census walks hoverfly activities were recorded as the height of each individual flying, their activities (flying or feeding) and resting (e.g. staying beneath plant leaves).\u003c/p\u003e \u003cp\u003eForaging behaviour was recorded for each \u003cem\u003ePlatycheirus\u003c/em\u003e individual seen visiting flowers. Their foraging bout was followed until they had visited five different individual flowers, for which visit durations were recorded and time spent shuttling between flowers calculated (Mi\u0026ntilde;arro and Twizell, \u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e2015\u003c/span\u003e). Sometimes it was difficult to assess visitation rate because some syrphids commonly completed their feeding bout after only one or two flowers, and then either stopped feeding (going to rest on the flower or on nearby leaves, usually to clean), or just flew away, to minimize this limitation, visitation rate was calculated only for individuals that remained within the observation area for a minimum observation period.\u003c/p\u003e \u003cp\u003eA hand net and aspirator were used for capturing hoverflies (Leereveld et al., \u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e1976\u003c/span\u003e; Petanidou et al., \u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e2011\u003c/span\u003e). Captured individuals were then placed in a specific glass container, numbered and euthanized in the laboratory by freezing for further identification and diagnosis. Stubbs a Falk\u0026rsquo;s (2002) key was used for nomenclature of specimens.\u003c/p\u003e \u003cp\u003eWeather conditions, represented by ambient temperature, wind speed and relative humidity (R.H.), were recorded immediately with each observation. A mercury thermometer was used for measuring temperature. When first seen, we recorded whether the individual was in direct sunlight or in shade. A psychrometer was used for measuring atmosphere relative humidity every hour during the days when flies were sampled (Maier and Waldbauer \u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e1979\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eThe data were combined with data from Gilbert's (1981) study from Cambridge with very similar methodology, in order to increase the number of species available. The data were transformed to the proportion of observations for each individual species performing specific activity to distinguish a number of species behaviour changes in relative to their environmental conditions (following Gilbert, \u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e1985\u003c/span\u003e). As an index of the temperature response, the lowest temperature at which 50% of individuals are active was estimated from the plot of temperature vs. %active (see Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e3\u003c/span\u003ea), and was taken as a species-specific characteristic. The overall percentage of individuals active in the shade was also taken to be a species-specific characteristic.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eAll statistical analysis were implemented in R 3.4.0 environment (R development core team, 2017).\u003c/p\u003e"},{"header":"3. Results","content":"\u003cp\u003eA total of 1842 specimens of hoverflies were collected, representing ten species (Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e), eight \u003cem\u003ePlatycheirus\u003c/em\u003e and two \u003cem\u003eMelanostoma\u003c/em\u003e. Combined numbers showed that specimens were seen in the morning much more abundantly than in the afternoon, accounting for about 60% (morning) and 40% (afternoon). Females were more common in the sample, accounting for about 65.5% (morning) and 59.3% (afternoon). The most dominant \u003cem\u003ePlatycheirus\u003c/em\u003e species by far was \u003cem\u003eP. albimanus\u003c/em\u003e, accounting for about 55.5% of all \u003cem\u003ePlatycheirus\u003c/em\u003e individuals. \u003cem\u003eMelanostoma scalare\u003c/em\u003e was just as common as \u003cem\u003eP.albimanus\u003c/em\u003e: together these two species represented 70% of the sample. In contrast to \u003cem\u003eP. albimanus\u003c/em\u003e, several species were rare, with only two observation for both \u003cem\u003eP. angustatus\u003c/em\u003e and \u003cem\u003eP. tarsalis\u003c/em\u003e. Our analysis focused on the seven most abundant species (Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e).\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eNumber of individuals of all species recorded during fieldwork.\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"12\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c8\" colnum=\"8\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c9\" colnum=\"9\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c10\" colnum=\"10\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c11\" colnum=\"11\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c12\" colnum=\"12\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colspan=\"3\" nameend=\"c5\" namest=\"c3\"\u003e \u003cp\u003edata from Nottingham\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colspan=\"3\" nameend=\"c10\" namest=\"c8\"\u003e \u003cp\u003edata from Cambridge\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c11\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c12\"\u003e\u0026nbsp;\u003c/th\u003e \u003c/tr\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eam\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003epm\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c8\"\u003e \u003cp\u003eam\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c9\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c10\"\u003e \u003cp\u003epm\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c11\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c12\"\u003e\u0026nbsp;\u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003especies\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003em\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003ef\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003em\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003ef\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003etotal\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003em\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003ef\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003em\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003ef\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e \u003cp\u003etotal\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c12\"\u003e \u003cp\u003eGrand Total\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cem\u003eP. albimanus\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e23\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e41\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e50\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e70\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e184\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e52\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e72\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e75\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e86\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e \u003cp\u003e285\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c12\"\u003e \u003cp\u003e469\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cem\u003eP. peltatus\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e30\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e27\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e22\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e18\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e \u003cp\u003e97\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c12\"\u003e \u003cp\u003e105\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cem\u003eP. manicatus\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e32\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e22\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e42\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e \u003cp\u003e98\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c12\"\u003e \u003cp\u003e102\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cem\u003eP. clypeatus\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e16\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e52\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e14\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e14\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e \u003cp\u003e96\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c12\"\u003e \u003cp\u003e100\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cem\u003eP. scutatus\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e11\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e22\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e41\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e \u003cp\u003e18\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c12\"\u003e \u003cp\u003e59\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cem\u003eP. fulviventris\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e12\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c12\"\u003e \u003cp\u003e12\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cem\u003eP. angustatus\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c12\"\u003e \u003cp\u003e2\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cem\u003eP. tarsalis\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c12\"\u003e \u003cp\u003e2\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cem\u003eM. scalare\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e39\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e74\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e18\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e46\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e177\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e157\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e311\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e51\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e109\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e \u003cp\u003e628\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c12\"\u003e \u003cp\u003e805\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cem\u003eM. mellinum\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e43\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e90\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e19\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e25\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e \u003cp\u003e177\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c12\"\u003e \u003cp\u003e186\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\u003eNo species were observed active at dawn apart from \u003cem\u003eM. scalare\u003c/em\u003e, a shade tolerant species whose activity commenced at 05:00 h (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e2\u003c/span\u003e). The proportion of active individuals (flying or feeding) increased in all species as the morning progressed, usually commencing at about 7:00h and reaching a peak before noon at 11:00h. comprising about (60%-80%) of the total observations (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e2\u003c/span\u003e). A slight reduction in activity was recorded during the early afternoon, corresponding with higher temperatures and lower relative humidity. A relatively constant 40% \u0026minus;\u0026thinsp;50% of observations for the most species were recorded between 12:00h and 13:00h, and then this proportion declined drastically thereafter at 15:00h. The two species \u003cem\u003eP. peltatus\u003c/em\u003e and \u003cem\u003eP. clypeatus\u003c/em\u003e shows a slightly rebound in their activity between 13:00 and 14:00 h (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e2\u003c/span\u003e). All observations after 15:00h were specimens seen at rest. Pollen feeding was always during the morning, whereas most specimens were feeding on nectar during the early afternoon, especially on hot days. Because the length of time of the day varies substantially from spring to summer, activity is analyzed in relation to weather variables rather than time.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eThe most favourable temperatures for most species were between 13\u0026ndash;23\u0026deg;C (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e3\u003c/span\u003e) except for \u003cem\u003eP. albimanus\u003c/em\u003e and \u003cem\u003eM. scalare\u003c/em\u003e, which commenced their activity at 12\u0026deg;C. Flight behaviour was correlated directly with temperature. During the course of the day, species did not fly until temperatures began to rise. As the temperature became high they flew relatively faster and shorter flights that were largely restricted to shaded regions. The height of the flights was negatively correlated with ambient temperature (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003e). Above 20\u0026deg;C the active behaviours (flying or feeding) were limited to shaded regions or under cloudy conditions, whereas below 20\u0026deg;C flight was much more restricted to habitats with direct sunlight. The index of the temperature responses of the species (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e3\u003c/span\u003e, Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e) showed only small differences, except perhaps for \u003cem\u003eM.scalare\u003c/em\u003e being lower than other species. There was detectable phylogenetic signal in neither Pagel's λ (λ\u0026thinsp;=\u0026thinsp;0.006, p\u0026thinsp;=\u0026thinsp;0.91, n\u0026thinsp;=\u0026thinsp;7) or Blomberg's K (K\u0026thinsp;=\u0026thinsp;0.022, p\u0026thinsp;=\u0026thinsp;0.81, n\u0026thinsp;=\u0026thinsp;7).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab2\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eThe temperature at which 50% of the individual hoverflies were active (estimated from the graphs in Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e3\u003c/span\u003e).\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"2\"\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 \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSpecies\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eestimated temperature\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cem\u003eP. scutatus\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e13.3\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cem\u003eP. albimanus\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e12.3\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cem\u003eP. clypeatus\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e13.3\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cem\u003eM. scalare\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e12.3\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cem\u003eM. mellinum\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e14.0\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cem\u003eP. manicatus\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e13.3\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cem\u003eP. peltatus\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e14.3\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\u003eIn terms of relative humidity, the activities of most species fell in the range 50%-80% (Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003e), with the exception of \u003cem\u003eM. scalare\u003c/em\u003e which remained active to 90% R.H. \u003cem\u003eP. albimanus\u003c/em\u003e tended to feed on pollen at high R.H., and nectar at low R.H. (Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003e). The activities of most species declined (and resting behaviour increased) with increasing humidity, with nearly all activities ceasing above 90% R.H. (Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003e). The exceptions were \u003cem\u003eP. albimanus\u003c/em\u003e and \u003cem\u003eM. scalare\u003c/em\u003e, which remained active even at high R.H.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eThe times spent to forage on five individual flowers were recorded for some of the \u003cem\u003ePlatycheirus\u003c/em\u003e and \u003cem\u003eMelanostoma\u003c/em\u003e species seen visiting flowers for nectar or pollen (Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e). Although tested with too few data, there was no overall difference in foraging times for pollens versus nectar (Wilcoxon signed rank statistic, W\u0026thinsp;=\u0026thinsp;41.5, p\u0026thinsp;=\u0026thinsp;0.18). There was an obvious pattern in that species spent more time to forage five flowers in the morning than later in the day (Fig.\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e8\u003c/span\u003e), which is clearly temperature-related. We used the means of these foraging speeds to estimating the level of phylogenetic signal. Although with few data, the results for both Pagel's (λ\u0026thinsp;=\u0026thinsp;0.53, p\u0026thinsp;=\u0026thinsp;0.58, n\u0026thinsp;=\u0026thinsp;5) and Blomberg's (K\u0026thinsp;=\u0026thinsp;0.81, p\u0026thinsp;=\u0026thinsp;0.11, n\u0026thinsp;=\u0026thinsp;5) methods suggest that this behavioural trait is not constrained phylogenetically. Moreover, when the proportion of active species were calculated under cloudy cover, the estimated phylogenetic signal results for both Pagel\u0026rsquo;s and Blomberg\u0026rsquo;s K were also non-significant (λ\u0026thinsp;=\u0026thinsp;0.0066, p\u0026thinsp;=\u0026thinsp;0.89, n\u0026thinsp;=\u0026thinsp;8) and Blomberg's (K\u0026thinsp;=\u0026thinsp;0.175, p\u0026thinsp;=\u0026thinsp;0.454, n\u0026thinsp;=\u0026thinsp;8), this suggest that species flew under cloud cover have no evolutionary relationships with the species common ancestor.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e"},{"header":"4. Discussion","content":"\u003cp\u003eInsect diurnal activity rhythms are influenced by a number of environmental variables, but because of the presence of intercorrelations between them, caution must be taken when assessing the causes of the diurnal activity patterns (Mi\u0026ntilde;arro and Twizell, \u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e2015\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eThe patterns of insect activity seen in nature is probably mainly determined by interactions between thermal balance and intrinsic diel rhythmicity, and body size has a great influence upon thermal balance (Wilmer, 1983; Gilbert, \u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e1985\u003c/span\u003e). Different authors have investigated syrphid behaviours and their diurnal patterns. Lewis and Taylor (\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e1965\u003c/span\u003e) recorded flight activity patterns for different species including hoverflies. Both \u003cem\u003eMetasyrphus corolla\u003c/em\u003e and \u003cem\u003eEpisyrphus balteatus\u003c/em\u003e have their maximum activities soon after sunrise where as \u003cem\u003eMelanostoma mellinum\u003c/em\u003e L. has been found visiting flowers before sunrise (Morse, \u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e1981\u003c/span\u003e) and in the very early morning (Vlaš\u0026aacute;nkov\u0026aacute; et al., \u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e2017\u003c/span\u003e). \u003cem\u003eRhingia mecyana\u003c/em\u003e was the most frequent flower visitor before and after noon (Vlaš\u0026aacute;nkov\u0026aacute; et al., \u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e2017\u003c/span\u003e), and a peak near mid-morning was the pattern of some syrphids (Maier and Waldbauer, \u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e1979\u003c/span\u003e). During the hot summer, some Mediterranean syrphids such as \u003cem\u003eEumerus\u003c/em\u003e and \u003cem\u003eMerodon\u003c/em\u003e species are crepuscular (Ssymnak, unpublished, cited by Inouye et al., \u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e2015\u003c/span\u003e), and \u003cem\u003eVolucella vesicularia\u003c/em\u003e can only be collected in large numbers during its crepuscular flower visiting (Waldbauer, \u003cspan citationid=\"CR37\" class=\"CitationRef\"\u003e1963\u003c/span\u003e). Bimodal diel periodicity can also be a feature in some syrphid flies, for instance, \u003cem\u003eScaeva pyrastri\u003c/em\u003e coming to artificial flowers in March (Willmer and Unwin \u003cspan citationid=\"CR40\" class=\"CitationRef\"\u003e1981\u003c/span\u003e), caused by long-distance (up to 5 km) daily circulation between feeding and resting places. All these patterns are explicable in term of relation to microclimatic condition and foraging behaviours.\u003c/p\u003e \u003cp\u003eThe activity of \u003cem\u003ePlatycheirus\u003c/em\u003e species reached a peak around mid-morning, before noon, indicating a unimodal pattern of activity. This pattern could be explained in many ways. One possible explanation may be a reduction in competition with other species, since larger flies can be more vulnerable to direct insolation and higher midday temperatures, which may increase the risk of overheating and dehydration. (Willmer and Unwin \u003cspan citationid=\"CR40\" class=\"CitationRef\"\u003e1981\u003c/span\u003e; Herrera, \u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e1990\u003c/span\u003e). The prevalence of hot, dry conditions and greater availability of food in the morning is another explanation (D'Amen et al., \u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e2013\u003c/span\u003e). However, some flies do not follow this pattern: for instance, \u003cem\u003eSarcophaga\u003c/em\u003e (Sarcophagidae) in Britain are capable of visiting flowers in the middle of the day even though they are rather large and blackish in colour (Willmer, \u003cspan citationid=\"CR41\" class=\"CitationRef\"\u003e1982a\u003c/span\u003e). Some other flies can be inactive during the warm periods of the day, such as \u003cem\u003eCalliphora\u003c/em\u003e (Calliphoridae): even though they are metallic, they are unable to regulate their body temperature as efficiently as \u003cem\u003eSarcophaga\u003c/em\u003e species (Inouye et al., \u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e2015\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eFor small, dark-coloured flies, direct sunlight can be physiologically stressful while visiting flowers. They can take advantage of the local shade to lower their temperature excess, allowing them to visit flowers during the warmest part of the day (Willmer and Unwin, \u003cspan citationid=\"CR40\" class=\"CitationRef\"\u003e1981\u003c/span\u003e). When insolation is low, the flower-visiting activity of small anthophilous flies decreases during the course of the day, only beginning to forage when the temperature rises: small flies can stay warm by foraging in sun-flecks (Rotheray and Gilbert, \u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e2011\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eThe observed temporal patterns of foraging activities can be explained by physiological constraints. For instance, the temperature at early morning and afternoon might only be appropriate for foraging for relativity non-reflective and large flies, with the mid-day being too warm for foraging (Inouye et al., \u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e2015\u003c/span\u003e). This produces a bimodal pattern of activity, as shown for Syrphidae on Apiaceae flowers in Britain (Willmer \u003cspan citationid=\"CR43\" class=\"CitationRef\"\u003e1983\u003c/span\u003e) and Lamiaceae flowers in Spain (Herrera, \u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e1990\u003c/span\u003e). This pattern changes to unimodal activity on cool days (Willmer, \u003cspan citationid=\"CR42\" class=\"CitationRef\"\u003e1982b\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eSyrphid flies visit the flowers of many different plant species, and their visitation rate is mainly determined by activity levels. Herrera (\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e1990\u003c/span\u003e) mentioned that the visitation rate relies on both flight time (the time spent flying between flowers) and handling time (the time spent extracting the rewards). Our results showed that \u003cem\u003ePlatycheirus\u003c/em\u003e spp. spent more time for foraging in the morning than they did late in the day, possibly an indication that overheating avoidance is more important than the availability of rewards. Wilmer (1983) mentioned this foraging pattern for flies on \u003cem\u003eTilia\u003c/em\u003e and \u003cem\u003eHeracleum\u003c/em\u003e flowers, and this has been corroborated by other studies (e.g. Herrera, \u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e1990\u003c/span\u003e, who also indicated that fly activity rhythms do not reflect reward availability).\u003c/p\u003e \u003cp\u003eNormally, northern temperate flowers produce nectar and pollen in the early morning, and the concentration and secretion of nectar vary through the course of the day in relation to humidity and temperature (Corbet et al., \u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e1979\u003c/span\u003e; Goldberg, \u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e2009\u003c/span\u003e). Flight can be energetically very expensive, and optimal foraging models predict that anthophiles should ensure that their foraging decisions lead to a net energy gain (Pyke, \u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e1978\u003c/span\u003e). This pattern has been shown in hoverflies (Gilbert, \u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e1985\u003c/span\u003e) by a significant negative correlation between individual syrphid thoracic volume and the percentage of time spent flying, while no similar correlations appeared with time spent on feeding or resting.\u003c/p\u003e \u003cp\u003eOur analysis suggests that times of the day are important for interpreting \u003cem\u003ePlatycheirus\u003c/em\u003e behaviours in relation to microclimatic conditions, something well supported by the large literature on the ecology of hoverflies (Maier and Waldbauer, \u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e1979\u003c/span\u003e; Gilbert, \u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e1985\u003c/span\u003e; H\u0026ouml;vemeyer, \u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e1995\u003c/span\u003e; D\u0026rsquo;Amen et al., 2013). Generally, it is thought that morphological and physiological traits are more conservative than behavioural traits (Rheindt et al., \u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e2004\u003c/span\u003e). By estimating the level of phylogenetic signal in times that species spent to forage on five different flower (Table\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e), it was clearly appeared that foraging behaviour patterns was not constrained phylogenetically, this was supported by literature that behavioural traits are evolutionary more labile (Blomberg et al., \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2003\u003c/span\u003e; Gittleman et al., \u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e1996\u003c/span\u003e; Rheindt et al., \u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e2004\u003c/span\u003e). Moreover, the phylogenetic inertia was also lack when we estimated it in the ecological characters (i.e. temperature at which 50% of the individual commenced their activity), again this was supported by presence of insignificant level of phylogenetic signal in responses of different species to temperature.\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\u003eAverage visit duration time spent for each species to forage on five different kinds of flowers.\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=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSpecies\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eKind of flower\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eKind of food\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eAverage time spent/min.\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eSex\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cem\u003eP. albimanus\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u003cem\u003eRanunculus\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003epollen\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e4:40\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eM\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u003cem\u003eRanunculus\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003enectar\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e3:37\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eF\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u003cem\u003eCruciferae\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003epollen\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e5:37\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eM\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u003cem\u003eRubus fruticosus\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003epollen\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e2.40\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eM\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u003cem\u003eRubus fruticosus\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003epollen\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e5:27\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eF\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u003cem\u003eTanacetum parthenium\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003epollen\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e3:21\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eM\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u003cem\u003eCrepis\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003enectar\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e4:54\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eM\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u003cem\u003eErodium\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003epollen\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e4:11\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eF\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u003cem\u003eApiaceae\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003epollen\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e5:41\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eF\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u003cem\u003eSilene noctiflora\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003enectar\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e5:26\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eM\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cem\u003eP. scutatus\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u003cem\u003eRanunculus\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003epollen\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e3:23\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eM\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u003cem\u003eRanunculus\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003epollen\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e2:25\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eF\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u003cem\u003eGeum urbanum\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003epollen\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e3:41\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eF\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cem\u003eP. fulviventris\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u003cem\u003ePlantago lanceolata\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003epollen\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e6:12\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eM\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cem\u003eP. tarsalis\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u003cem\u003eErodium\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003enectar\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e1:47\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eM\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cem\u003eM. scalare\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u003cem\u003eAgrostis tenuis\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003epollen\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e11.23\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eM\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u003cem\u003eTaraxacum\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003epollen\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e2:28\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eF\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u003cem\u003eTaraxacum\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003epollen\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e8:24\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eM\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u003cem\u003eErodium\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003enectar\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e5:47\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eF\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u003cem\u003eRanunculus\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003epollen\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e9:47\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eF\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u003cem\u003eRanunculus\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003enectar\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e2:57\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eF\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e"},{"header":"Declarations","content":"\u003ch2\u003eFunding Information for Submitted Manuscript\u003c/h2\u003e \u003cp\u003eI would like to confirm that my PhD studies are financially supported by the Higher Committee for Education Development under grant number D1202023. The submitted manuscript represents part of the research conducted within the framework of this funded PhD project. The funding body provided financial support for my doctoral research, which includes the work presented in this paper.\u003c/p\u003e \u003cp\u003eThe funding organization had no involvement in the study design, data collection, analysis, interpretation of results, or the decision to submit the manuscript for publication.\u003c/p\u003e\u003ch2\u003eAuthor Contribution\u003c/h2\u003e\u003cp\u003e1- Aram Afrasiaw Ahme Jaf wrote the main manuscript.2- Emad Dawood Abbas Kaky did the data analysis.3- Francis Gilbert review the manuscript and was my supervisor during achieving my PhD thesis.\u003c/p\u003e\u003ch2\u003eAcknowledgements\u003c/h2\u003e \u003cp\u003eWe thank Jeff Skevington and Young Andrew for helping species identifications; Matthew Symonds for the first incredible review and comments on the paper. We also thank the Higher Committee for Education Development in Iraq (HCED) for achieving scholarship for student studying.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eBell W (1990). Searching behaviour patterns in insects. Annual Review of Entomology 35(1): 447\u0026ndash;467.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBlomberg S, Garland T, Ives A (2003). Testing for phylogenetic signal in comparative data: behavioural traits are more labile. Evolution, 57(4): 717\u0026ndash;745.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBoyle-Makowski R, Philogene, B (1985). Pollinator activity and abiotic factors in an apple orchard. Canadian Entomologist, 117(12): 1509\u0026ndash;1521.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBurgio G, Sommaggio D (2007). Syrphids as landscape bioindicators in Italian agroecosystems. 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Ecological Entomology, 8(4): 455\u0026ndash;469.\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":true,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"Syrphidae, Flower flies, Periodic activity, foraging behaviours, environmental factors","lastPublishedDoi":"10.21203/rs.3.rs-8790774/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-8790774/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eHoverflies are important plant pollinators which frequently visit flowers of many kinds of plant species. Although some aspects of the Syrphidae are well studied, the environmental conditions, foraging behaviours and activity rhythms of species within genera need further study in an evolutionary context. We considered the temporal activity rhythms of \u003cem\u003ePlatycheirus\u003c/em\u003e species to environmental factors such as ambient temperature and Relative Humidity (RH). \u003cem\u003ePlatycheirus\u003c/em\u003e activity depended mainly on temperature, and the individual species responded differently: the optimum temperature for achieving activity was between 13\u0026ndash;23\u0026deg;C. The proportion of active individuals increased as the morning progressed, peaking before noon, indicating a unimodal activity pattern. Flight behaviour correlated negatively with temperature. Most observations fell between 50% \u0026minus;\u0026thinsp;80% RH. Males and females were similar in handling times on flowers, taking nectar and pollen, as well as the kinds of flower used. Handling times in the morning were longer than in the afternoon. Foraging speed not constrained phylogenetically (i.e species spent different times for foraging). Understanding behavioural responses to microclimate is a necessary component of insect adaptations to their environment.\u003c/p\u003e","manuscriptTitle":"Diurnal activity patterns of Platycheirus hoverflies (Diptera: Syrphidae)","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2026-03-18 09:43:17","doi":"10.21203/rs.3.rs-8790774/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"5b3398f0-4e06-424e-ac2c-843dcb245d1c","owner":[],"postedDate":"March 18th, 2026","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2026-04-15T05:09:02+00:00","versionOfRecord":[],"versionCreatedAt":"2026-03-18 09:43:17","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-8790774","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-8790774","identity":"rs-8790774","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}