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  • 1.
    Abbott, Jessica K.
    et al.
    Queen's University.
    Gosden, Thomas P.
    Lund University.
    Correlated morphological and colour differences among females of the damselfly Ischnura elegans2009In: Ecological Entomology, ISSN 0307-6946, E-ISSN 1365-2311, Vol. 34, no 3, p. 378-386Article in journal (Refereed)
    Abstract [en]

    1. The female-limited colour polymorphic damselfly Ischnura elegans has proven to be an interesting study organism both as an example of female sexual polymorphism, and in the context of the evolution of colour polymorphism. The study of colour polymorphism can also have broader applications as a model of speciation processes.

    2. Previous research suggests that there exist correlations between colour morph and other phenotypic traits, and that the different female morphs in I. elegans may be pursuing alternative phenotypically integrated strategies. However, previous research on morphological differences in southern Swedish individuals of this species was only carried out on laboratory-raised offspring from a single population, leaving open the question of how widespread such differences are.

    3. We therefore analysed multi-generational data from 12 populations, investigating morphological differences between the female morphs in the field, differences in the pattern of phenotypic integration between morphs, and quantified selection on morphological traits.

    4. We found that consistent morphological differences did indeed exist between the morphs across all study populations, confirming that the previously observed differences were not simply a laboratory artefact.  We also found, somewhat surprisingly, that despite the existence of sexual dimorphism in body size and shape, patterns of phenotypic integration differed most between the morphs and not between the sexes. Finally, linear selection gradients showed that female morphology affected fecundity differently between the morphs.

    5. We discuss the relevance of these results to the male mimicry hypothesis and to the existence of potential ecological differences between the morphs.

  • 2.
    Andersson, Petter
    et al.
    Stockholm University, Faculty of Science, Department of Botany.
    Hambäck, Peter A.
    Stockholm University, Faculty of Science, Department of Botany.
    What shapes local density?: The importance of migration rates and local growth for density-patch size relationships in two Cionus weevils2012In: Ecological Entomology, ISSN 0307-6946, E-ISSN 1365-2311, Vol. 37, no 1, p. 90-98Article in journal (Refereed)
    Abstract [en]

    1. The relative effect of migration and local growth on the spatio-temporal density-distribution of two co-existing herbivorous weevils, Cionus scrophulariae L. and C. tuberculosus Scop., in 32 host plant Scrophularia nodosa L. patches of varying sizes was investigated. 2. Predictions of the temporal development of the slope in the density-patch size relationships were derived from a basic population model with scale-dependent migration rates. The model indicated that the slopes in the density-patch size relationships during the early season should be reflected by the net scaling of immigration and emigration rates, whereas the slopes during the later season should increase as a result of local growth. 3. Emigration rates of the weevils were estimated in a field experiment, were the weevils coexisted in space and time. These results were then combined with a previous estimate of immigration rates in order to determine the net scaling of migration rates. 4. The emigration rate differed between species, caused by different movement rates in small patches, which could explain differences in the general slope of the density-patch size relationships of the weevils in the natural figwort patches throughout the summer. The slopes in the relationships in the early season were largely predicted by the net scaling of migration rates. The slope also increased in the later season for C. tuberculosus, whereas the slope decreased for C. scrophulariae. 5. It was concluded that the understanding of both inter- and intra-specific variations in density-patch size relationships of insect herbivores can be improved using population models incorporating scale-dependent migration and local growth.

  • 3. Baba, Yuki G.
    et al.
    Walters, Richard J.
    Stockholm University, Faculty of Science, Department of Zoology.
    Miyashita, Tadashi
    Host-dependent differences in prey acquisition between populations of a kleptoparasitic spider Argyrodes kumadai (Araneae Theridiidae)2007In: Ecological Entomology, ISSN 0307-6946, E-ISSN 1365-2311, Vol. 32, no 1, p. 38-44Article in journal (Refereed)
    Abstract [en]

    1. A kleptoparasitic spider, Argyrodes kumadai, is known to use phylogenetically unrelated host species in different regions - Cyrtophora moluccensis (Araneidae) in south-west Japan and Agelena silvatica (Agelenidae) in north-east Japan. The work reported here examined whether differences in host characters affect prey acquisition of A. kumadai. 2. Field surveys showed that prey-biomass capture rate of Argyrodes was significantly higher in populations parasitising Cyrtophora than in populations parasitising Agelena. Although Argyrodes appeared to catch fewer prey within Cyrtophora webs, they were able to feed upon substantially larger prey. 3. Differences in prey-biomass capture rate were found to reflect differences in host traits rather than regional differences in potential prey availability. Individuals in populations parasitising Cyrtophora were observed to acquire prey via a number of foraging tactics that included stealing wrapped food bundles, feeding upon prey remains and, in the case of large prey items, feeding together with the host. In contrast, individuals in populations parasitising Agelena were only ever observed to feed upon small prey items ignored by its host. 4. This variability in prey acquisition between kleptoparasite populations reflected different opportunities for feeding within their respective host webs - opportunities that were primarily determined by the foraging behaviour of the host. One key trait associated with host foraging behaviour was host-web structure, namely the presence/absence of a retreat.

  • 4.
    Bergström, Anders
    et al.
    Stockholm University, Faculty of Science, Department of Zoology.
    Janz, Niklas
    Stockholm University, Faculty of Humanities, Centre for the Study of Cultural Evolution. Stockholm University, Faculty of Science, Department of Zoology.
    Nylin, Sören
    Stockholm University, Faculty of Science, Department of Zoology.
    Putting more eggs in the best basket: clutch size regulation in the comma butterfly2006In: Ecological Entomology, ISSN 0307-6946, E-ISSN 1365-2311, Vol. 31, no 3, p. 255-260Article in journal (Refereed)
    Abstract [en]

    1. Many studies have identified different factors influencing clutchsize regulation, primarily within various groups of insects. One prediction is that ovipositing females should increase clutch size with host quality. However, in many studies it is not clear whether ovipositing females are responding to host quality or quantity.

    2. Females of the polyphagous comma butterfly, allowed to oviposit on two hosts differing greatly in quality: the preferred host, stinging nettle (Polygonia c-album (L.), wereUrtica dioica L.), and the low-ranked host, birch (Betula pubescens  Ehrh). Ovipositing females were observed visually and clutch sizes were recorded. The experiment was repeated in three different years; in total, 938 observations of oviposition events were made.

    3. In all three years, females ovipositing on (median 1.6–1.85) compared with females ovipositing on 1.0–1.3) three years were pooled.

    4. Thus, on better hosts. It is suggested that the proximate mechanism is likely to be a response to the same stimuli used for female ranking of host plants in the preference hierarchy. U. dioica laid larger clutchesB. pubescens (median. The difference was significant in two out of three years and when allP. c-album females exhibit clutch-size regulation, with larger clutches

  • 5.
    Betzholtz, Per-Eric
    et al.
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Franzén, Markus
    Department of Community Ecology, UFZ Centre for Environmental Research, Halle, Germany.
    Mobility is related to species traits in noctuid moths2011In: Ecological Entomology, ISSN 0307-6946, E-ISSN 1365-2311, Vol. 36, p. 369-376Article in journal (Refereed)
    Abstract [en]

    Abstract. 1. Mobility is important for the understanding of how species survive infragmented landscapes and cope with increasing rates of habitat and climate change.However, mobility is a difficult trait to explore and is poorly known in most taxa.Species traits have been studied in relation to range shifts, extinction risks, andresponses to habitat area and isolation, and have also been suggested as good estimatorsof mobility. Here we explore the relation between mobility and species traits in noctuidmoths.2. We sampled noctuid moths by an automatic light-trap on an island far out in theBaltic Sea. We compared traits of the non-resident species on the island with traits ofa species pool of assumed potential migrants from the Swedish mainland.3. Mobility was significantly related to adult activity period, length of flightperiod, and the interaction between host-plant specificity and distribution area. Widelydistributed host-plant generalists were more mobile than host-plant specialists withmore restricted distribution, and species with an adult activity period in August toSeptember moved to the island to a higher extent than species with an adult activityperiod in May to July. Our results remained qualitatively robust in additional analyses,after controlling for phylogeny and including all species recorded on the island, exceptfor the trait ‘length of flight period’.4. Our results highlight the importance of the relation between mobility and speciestraits. Noctuid moths with certain traits move over longer distances than earlier known.This finding is important to include when predicting range dynamics in fragmentedand changing landscapes, and when conservation measures of species are devised.

  • 6. Dalin, Peter
    et al.
    Nylin, Sören
    Stockholm University, Faculty of Science, Department of Zoology.
    Host-plant quality adaptively affects the diapause threshold: evidence from leaf beetles in willow plantations2012In: Ecological Entomology, ISSN 0307-6946, E-ISSN 1365-2311, Vol. 37, no 6, p. 490-499Article in journal (Refereed)
    Abstract [en]

    1. Voltinism of herbivorous insects can vary depending on environmental conditions. The leaf beetle Phratora vulgatissima L. is univoltine in Sweden but will sometimes initiate a second generation in short-rotation coppice (SRC) willow plantations. 2. The study investigated whether increased voltinism by P. vulgatissima in plantations can be explained by (i) rapid life-cycle development allowing two generations, or (ii) postponed diapause induction on coppiced willows. 3. In the field, no difference was found in the phenology or development of first-generation broods between plantations (S. viminalis) and natural willow habitats (S. cinerea). However, the induction of diapause occurred 12 weeks later in SRC willow plantations. 4. Laboratory experiments indicated no genetic difference in the critical day-length for diapause induction between beetles originating from plantations and natural habitats. Development time was unaffected by host-plant quality but critical day-length was prolonged by almost an hour when the beetles were reared on a non-preferred willow species (S. phylicifolia). When reared on new leaves from re-sprouting shoots of recently coppiced willow plants, diapause incidence was significantly less than when the beetles were reared on mature leaves from uncoppiced plants. 5. The study suggests that P. vulgatissima has a plastic diapause threshold influenced by host-plant quality. The use of host-plant quality as a diapause-inducing stimulus is likely to be adaptive in cases where food resources are unpredictable, such as when new host-plant tissue is produced after a disturbance. SRC willows may allow two beetle generations due to longer growing seasons of coppiced plants that grow vigorously.

  • 7. Ekholm, Adam
    et al.
    Tack, Ayco J. M.
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Bolmgren, Kjell
    Roslin, Tomas
    The forgotten season: the impact of autumn phenology on a specialist insect herbivore community on oak2019In: Ecological Entomology, ISSN 0307-6946, E-ISSN 1365-2311, Vol. 44, no 3, p. 425-435Article in journal (Refereed)
    Abstract [en]

    1. Variation in spring phenology - like tree budburst - affects the structure of insect communities, but impacts of autumn phenology have been neglected. Many plant species have recently delayed their autumn phenology, and the timing of leaf senescence may be important for herbivorous insects.

    2. This study explored how an insect herbivore community associated with Quercus robur is influenced by variation in autumn phenology. For this, schools were asked to record, across the range of oak in Sweden, the autumn phenology of oaks and to conduct a survey of the insect community.

    3. To tease apart the relative impacts of climate from that of tree phenology, regional tree phenology was first modelled as a function of regional climate, and the tree-specific deviation from this relationship was then used as the metric of relative tree-specific phenology.

    4. At the regional scale, a warmer climate postponed oak leaf senescence. This was also reflected in the insect herbivore community: six out of 15 taxa occurred at a higher incidence and five out of 18 taxa were more abundant, in locations with a warmerclimate. Similarly, taxonomic richness and herbivory were higher in warmer locations.

    5. Trees with a relatively late autumn phenology had higher abundances of leaf miners (Phyllonorycter spp.). This caused lower community diversity and evenness on trees with later autumn phenology.

    6. The findings of the present study illustrate that both regional climate-driven patterns and local variation in oak autumn phenology contribute to shaping the insect herbivore community. Community patterns may thus shift with a changing climate.

  • 8.
    Flenner, Ida
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Animal Ecology.
    Olne, Karin
    Suhling, Frank
    Sahlen, Goran
    Predator-induced spine length and exocuticle thickness in Leucorrhinia dubia (Insecta: Odonata): a simple physiological trade-off?2009In: Ecological Entomology, ISSN 0307-6946, E-ISSN 1365-2311, Vol. 34, no 6, p. 735-740Article in journal (Refereed)
    Abstract [en]

    1. Morphological defence structures evolve against predators but are costly to the individual, and are induced only when required. A well-studied example is the development of longer abdominal spines in dragonfly larvae in the presence of fish. Numerous attempts to discover trade-offs between spine size and behaviour, development time or body size have, however, produced little evidence. 2. We considered a physiological trade-off. Spines consist of cuticle and using material to build longer structures may result in less material remaining elsewhere. We therefore measured exocuticle thickness at nine locations on Leucorrhinia dubia larvae from habitats with and without fish. 3. Our results show a significant effect of the interaction between fish presence and spine length on head and fore leg exocuticle thickness. Relative thickness increased with relative length of lateral spine 9 in the absence of fish, whereas no such relationship existed with fish. Hence, synthesis and secretion of cuticle material occur as a trade-off when larvae react to fish presence. 4. We assume the mechanism to be a selective synthesis of material with different responses in different parts of the larval body. These findings offer a new angle to the fish/spine trade off debate.

  • 9.
    Flenner, Ida
    et al.
    Halmstad University, School of Business and Engineering (SET), Biological and Environmental Systems (BLESS).
    Olne, Karin
    Halmstad University, School of Business and Engineering (SET), Biological and Environmental Systems (BLESS).
    Suhling, Frank
    Technische Universität Braunschweig.
    Sahlén, Göran
    Halmstad University, School of Business and Engineering (SET), Biological and Environmental Systems (BLESS).
    Predator-induced spine length and exocuticle thickness in Leucorrhinia dubia (Insecta: Odonata): a simple physiological trade-off?2009In: Ecological Entomology, ISSN 0307-6946, E-ISSN 1365-2311, Vol. 34, p. 735-740Article in journal (Refereed)
    Abstract [en]

    1. Morphological defence structures evolve against predators but are costly to the individual, and are induced only when required. A well-studied example is the development of longer abdominal spines in dragonfly larvae in the presence of fish. Numerous attempts to discover trade-offs between spine size and behaviour, development time or body size have, however, produced little evidence.

    2. We considered a physiological trade-off. Spines consist of cuticle and using material to build longer structures may result in less material remaining elsewhere. We therefore measured exocuticle thickness at nine locations on Leucorrhinia dubia larvae from habitats with and without fish.

    3. Our results show a significant effect of the interaction between fish presence and spine length on head and fore leg exocuticle thickness. Relative thickness increased with relative length of lateral spine 9 in the absence of fish, whereas no such relationship existed with fish. Hence, synthesis and secretion of cuticle material occur as a trade-off when larvae react to fish presence.

    4. We assume the mechanism to be a selective synthesis of material with different responses in different parts of the larval body. These findings offer a new angle to the fish/spine trade off debate.

     

     

  • 10. Friberg, Magne
    et al.
    Wiklund, Christer
    Stockholm University, Faculty of Science, Department of Zoology.
    Host preference variation cannot explain microhabitat differentiation among sympatric Pieris napi and Pieris rapae butterflies2019In: Ecological Entomology, ISSN 0307-6946, E-ISSN 1365-2311, Vol. 44, no 4, p. 571-576Article in journal (Refereed)
    Abstract [en]

    1. Often, closely related insect species feed on different host plant species, and the tremendous diversity of phytophagous insects is therefore attributed to host plant-driven speciation. However, for most taxa, host use information comes from field observations of egg-laying females or feeding caterpillars, which means that the underlying reason for a particular host-affiliation is not easily determined. 2. Therefore, it is often unclear whether an insect feeds on a certain host because it prefers that plant to alternative hosts, or because the host distribution overlaps with the habitat requirements of the insect. 3. We ask to what extent a divergent host use in the field mirrors the host plant preferences of two closely related butterflies, Pieris napi and Pieris rapae (Pieridae). In nature, P. napi typically occurs in moister habitats than P. rapae. 4. We scanned several microhabitats at a field site in Southern Sweden during multiple years, and collected Pieris eggs from three different plants, Cardamine pratensis (wet meadows), Barbarea vulgaris (drier micro-habitats) and Alliaria petiolata (intermediate areas). 5. As predicted, P. rapae eggs were more common than P. napi eggs on B. vulgaris, whereas all of the 358 individuals collected from C. pratensis were P. napi, indicating a divergence in host use between the Pieris species. However, under controlled laboratory conditions, both species had virtually identical oviposition preferences, laying eggs on all three plants, notably P. rapae also laying eggs on C. pratensis, indicating that habitat use, not plant preference, drives host plant use in nature.

  • 11.
    Hamback, Peter A.
    et al.
    Stockholm University, Faculty of Science, Department of Botany.
    Björkman, Maria
    Stockholm University, Faculty of Science, Department of Botany.
    Hopkins, Richard J.
    Patch size effects are more important than genetic diversity for plant-herbivore interactions in Brassica crops2010In: Ecological Entomology, ISSN 0307-6946, E-ISSN 1365-2311, Vol. 35, no 3, p. 299-306Article in journal (Refereed)
    Abstract [en]

    2. This paper examines the effect of intraspecific genetic diversity within Brassica fields on two Brassica specialists, cabbage root fly, and diamondback moth, and on a parasitoid attacking diamondback moths. Genetic diversity was manipulated both in a replacement and an additive design. 3. Both herbivore densities and parasitism rates were higher in smaller plots, with limited responses to increased within-plot diversity. All species showed variable densities across genotypes, and preference hierarchies were species specific. 4. Responses to plot size in root flies scaled with the diameter-to-area ratio, suggesting that patch detectability affected local density, whereas responses by diamondback moths and parasitoids deviated from this ratio. These species differences could be traced to differences in the residence time within patches, where diamondback moths typically spend longer and more variable time periods in patches than root flies. 5. The lack of response to genetic diversity by both herbivores suggests that egg-laying rates are affected by decisions on the plant and not by attraction from a distance, neither to the plant itself nor the patch. Patterns of differential attack may then be due to different acceptability for studied genotypes. 6. Future theories on insect responses to spatial heterogeneity should focus on species traits and how traits interact with information landscapes in the field.

  • 12. Härdling, R
    et al.
    Borg, A
    Carrasco, D
    Katvala, Mari
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Animal Ecology.
    Kaitala, A
    Male golden egg bugs (Phyllomorpha laciniata Vill.) do not preferentially accept their true genetic offspring: comment on the paper by García-González et al. (2005, Ecological Entomology, 30, 444–455)2007In: Ecological Entomology, ISSN 0307-6946, E-ISSN 1365-2311, Vol. 32, no 5, p. 575-577Article in journal (Refereed)
  • 13.
    Jander, K. Charlotte
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Plant Ecology and Evolution. Yale Univ, Dept Ecol & Evolutionary Biol, New Haven, CT USA. Smithsonian Trop Res Inst, Panama City, Panama..
    Indirect mutualism: ants protect fig seeds and pollen dispersers from parasites2015In: Ecological Entomology, ISSN 0307-6946, E-ISSN 1365-2311, Vol. 40, no 5, p. 500-510Article in journal (Refereed)
    Abstract [en]

    1. Mutualisms are ubiquitous and ecologically important, but may be particularly vulnerable to exploitation by species outside of the mutualism owing to a combination of an attractive reward and potentially limited defence options. For some mutualisms, ants can offer dynamic and relatively selective protection against herbivores and parasites. 2. The mutualism between fig trees and their pollinating wasps, a keystone mutualism in tropical forests, is particularly well suited for ant protection because pollinators are protected inside hollow inflorescences but parasites are exposed on the outside. 3. In the present study, it was shown that the presence of ants provides a fitness benefit for both the pollinators and the hosting fig tree. The presence of ants (i) reduced abortions of developing figs, (ii) reduced herbivory of figs, and (iii) reduced parasitic wasp loads, resulting in more pollinators and more seeds in ant-protected figs. Even when taking costs such as ant predation on emerging pollinators into account, the total fitness increase of hosting ants was threefold for the tree and fivefold for the pollinators. 4. It was further shown that the seemingly most vulnerable parasitic wasps, of the genus Idarnes, have a specific behaviour that allows them to evade ant attack while continuing to oviposit. 5. Ants were present on 79% of surveyed Panamanian fig trees. Together with previous studies from the Old World, the results found here imply that ants are both powerful and common protectors of the fig mutualism worldwide.

  • 14.
    Janz, Niklas
    et al.
    Stockholm University, Faculty of Science, Department of Zoology. Stockholm University, Faculty of Science, Department of Zoology, Department of Animal Ecology. Stockholm University, Faculty of Humanities, Centre for the Study of Cultural Evolution.
    Söderlind, Lina
    Stockholm University, Faculty of Science, Department of Zoology. Stockholm University, Faculty of Science, Department of Zoology, Department of Animal Ecology.
    Nylin, Sören
    Stockholm University, Faculty of Science, Department of Zoology. Stockholm University, Faculty of Science, Department of Zoology, Department of Animal Ecology.
    No effect of larval experience on adult host preferences in Polygonia c-album (Lepidoptera: Nymphalidae): on the persistence of Hopkins' host selection principle2009In: Ecological Entomology, ISSN 0307-6946, E-ISSN 1365-2311, Vol. 34, no 1, p. 50-57Article in journal (Refereed)
    Abstract [en]

    1. The possible effect of juvenile imprinting or 'chemical legacy' on the subsequent oviposition - often called the 'Hopkins' host selection principle' - has been a controversial but recurrent theme in the literature on host-plant preference. While it appears possible in principle, experimental support for the hypothesis is equivocal. The present study points out that it is also important to consider its theoretical implications, and asks under what circumstances, if any, it should be favoured by natural selection.

    2. Following this reasoning, it is predicted that host preference in the polyphagous butterfly Polygonia c-album L. (Lepidoptera, Nymphalidae) should not be influenced by larval environment. This was tested by rearing larvae on three natural host plants: the high-ranked Urtica dioica and the medium-ranked Salix cinerea and Ribes uva-crispa, and exposing the naive females to oviposition choices involving the same set of plants.

    3. It was found that larval host plant had no effect on oviposition decisions of the adult female. Hence, the Hopkins' host selection principle does not seem to be applicable in this species.

    4. Based on recent insights on how accuracy of environmental versus genetic information should affect the control of developmental switches, the conditions that could favour the use of juvenile cues in oviposition decisions are discussed. Although the Hopkins' host selection hypothesis cannot be completely ruled out, we argue that the circumstances required for it to be adaptive are so specific that it should not be invoked as a general hypothesis for host selection in plant-feeding insects.

     

  • 15.
    Johansen, Aleksandra I.
    et al.
    Stockholm University, Faculty of Science, Department of Zoology.
    Exnerová, Alice
    Hotová Svádová, Katerina
    Stys, Pavel
    Gamberale-Stille, Gabriella
    Stockholm University, Faculty of Science, Department of Zoology.
    Tullberg, Birgitta S.
    Stockholm University, Faculty of Science, Department of Zoology.
    Adaptive change in protective coloration in adultstriated shieldbugs Graphosoma lineatum (Heteroptera:Pentatomidae): test of detectability of two colour formsby avian predators2010In: Ecological Entomology, ISSN 0307-6946, E-ISSN 1365-2311, Vol. 35, no 5, p. 602-610Article in journal (Refereed)
    Abstract [en]

    1. Protective coloration in insects may be aposematic or cryptic, and some species change defensive strategy between instars. In Sweden, the adult striated shieldbugs Graphosoma lineatum (Heteroptera: Pentatomidae) undergo a seasonal colour change from pale brown and black striation in the pre-hibernating adults, to red and black striation in the same post-hibernating individuals. To the human eye the pre-hibernating adults appear cryptic against the withered late summer vegetation, whereas the red and black post-hibernating adults appear aposematic. This suggests a possibility of a functional colour change. However, what is cryptic to the human eye is not necessarily cryptic to a potential predator.

    2. Therefore we tested the effect of coloration in adult G. lineatum on their detectability for avian predators. Great tits (Parus major) were trained to eat sunflower seeds hidden inside the emptied exoskeletons of pale or red G. lineatum. Then the detection time for both colour forms was measured in a dry vegetation environment.

    3. The birds required a longer time to find the pale form of G. lineatum than the red one. The pale form appears more cryptic on withered late summer vegetation than the red form, not only to the human eye but also to avian predators. The result supports the idea that the adult individuals of G. lineatum undergo a functional change from a cryptic protective coloration to an aposematic one.

  • 16.
    Larsson, Magnus
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Ecological Botany. Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Ecological Botany.
    Franzén, Markus
    Estimating the population size of specialised solitary bees2008In: Ecological Entomology, ISSN 0307-6946, E-ISSN 1365-2311, Vol. 33, no 2, p. 232-238Article in journal (Refereed)
    Abstract [en]

    1. Reliable methods for quantifying population size are crucial for strategies to conserve endangered wild-bee species. Estimates of population size obtained through survey walks were compared with estimates obtained through mark–recapture studies in 10 populations of the red-listed solitary bee Andrena hattorfiana in southern Sweden.

    2. The mean number of bees observed during survey walks was strongly correlated with estimates of population size obtained with mark–recapture. It was found that 5.5–23.4% (mean 13.4%) of the total population was observed during an average survey walk.

    3. One component in mark–recapture analysis is the measure of survival of individuals. In the largest bee population, females of A. hattorfiana that emerged in early season were found to forage for pollen on average 18.4 days.

    4. The findings suggest that during large-scale surveys, for example re-inventories for red-listed species, the population size of solitary bees can be quantified reliably and effectively by performing survey walks in a two-step process. The first step consists of survey walks to establish the relationship between number of bee observations per survey walk and mark–recapture population size for a small set of populations. In the second, simple observation survey walks can be performed for a large set of populations. In each population of A. hattorfiana, it is recommended that at least six survey walks are performed.

  • 17.
    Maklakov, Alexei A.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution. Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Animal ecology.
    Fricke, Claudia
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution. Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Animal ecology.
    Sexual selection did not contribute to the evolution of male lifespan under curtailed age at reproduction in a seed beetle2009In: Ecological Entomology, ISSN 0307-6946, E-ISSN 1365-2311, Vol. 34, no 5, p. 638-643Article in journal (Refereed)
    Abstract [en]

    1. Sexual selection is a powerful evolutionary force that is hypothesised to play an important role in the evolution of lifespan. Here we test for the potential contribution of sexual selection to the rapid evolution of male lifespan in replicated laboratory populations of the seed beetle, Callosobruchus maculatus. 2. For 35 generations, newly hatched virgin male beetles from eight different populations were allowed to mate for 24 h and then discarded. Sexual selection was removed in half of these populations by enforcing random monogamy. 3. Classic theory predicts that because of sexual competition, males from sexually selected lines would have higher age-specific mortality rates and shorter lifespan than males from monogamous lines. 4. Alternatively, condition-dependent sexual selection may also favour genes that have positive pleiotropic effects on lifespan and ageing. 5. Males from all eight populations evolved shorter lifespans compared with the source population. However, there was no difference in lifespan between males from populations with or without sexual selection. Thus, sexual selection did not contribute to the evolution of male lifespan despite the fact that such evolution did occur in our study populations.

  • 18.
    Maklakov, Alexeia A.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution.
    Bilde, Trine
    Lubin, Yael
    Inter-sexual combat and resource allocation into body parts in the spider, Stegodyphus lineatus2006In: Ecological Entomology, ISSN 0307-6946, E-ISSN 1365-2311, Vol. 31, no 6, p. 564-567Article in journal (Refereed)
    Abstract [en]

    1. Sexual conflict, which results from the divergence of genetic interests between males and females, is predicted to affect multiple behavioural, physiological, and morphological traits. 2. Sexual conflict over mating may interact with population density to produce predictable changes in resource allocation into inter-sexual armament. 3. In the spider Stegodyphus lineatus, males fight with females over re-mating. The outcome of the fight is influenced by the cephalothorax size of the contestants. The investment in armament - the cephalothorax, may be traded-off against investment in abdomen, which is a trait that affects survival and fecundity. Pay-offs may depend on population density. Both sexes are expected to adjust resource allocation into different body parts accordingly. 4. Males had increased cephalothorax/body size ratio in low densities where probability of finding another receptive female is low and females had increased cephalothorax/body size ratio in high densities where cumulative costs of multiple mating are high. 5. The results support the theoretical conjecture that population density affects resource allocation into inter-sexual armament and call for further research on the interaction between sexual selection and population density.

  • 19.
    Metcalfe, Daniel B.
    et al.
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences. Department of Physical Geography and Ecosystem Science, Lund University, Lund, Sweden.
    Cherif, Mehdi
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Jepsen, Jane U.
    Vindstad, Ole Petter L.
    Kristensen, Jeppe A.
    Belsing, Ulrika
    Ecological stoichiometry and nutrient partitioning in two insect herbivores responsible for large-scale forest disturbance in the Fennoscandian subarctic2019In: Ecological Entomology, ISSN 0307-6946, E-ISSN 1365-2311, Vol. 44, no 1, p. 118-128Article in journal (Refereed)
    Abstract [en]

    1. Outbreaks of herbivorous insects can have large impacts on regional soil carbon (C) storage and nutrient cycling. In northernmost Europe, population outbreaks of several geometrid moth species regularly cause large‐scale defoliation in subarctic birch forests. An improved understanding is required of how leaf C and nutrients are processed after ingestion by herbivores and what this means for the quantity and quality of different materials produced (frass, bodies).

    2. In this study, larvae of two geometrid species responsible for major outbreaks (Epirrita autumnata and Operophtera brumata) were raised on exclusive diets of Betula pubescens var. czerepanovii (N. I. Orlova) Hämet Ahti and two other abundant understorey species (Betula nanaVaccinium myrtillus). The quantities of C, nitrogen (N) and phosphorus (P) ingested and allocated to frass, bodies and (in the case of C) respired were recorded.

    3. Overall, 23%, 70% and 48% of ingested C, N and P were allocated to bodies, respectively, rather than frass and (in the case of C) respiration. Operophtera brumata consistently maintained more constant body stoichiometric ratios of C, N and P than did E. autumnata, across the wide variation in physico‐chemical properties of plant diet supplied.

    4. These observed differences and similarities on C and nutrient processing may improve researchers' ability to predict the amount and stoichiometry of frass and bodies generated after geometrid outbreaks.

  • 20.
    Nylin, Sören
    et al.
    Stockholm University, Faculty of Science, Department of Zoology, Animal Ecology.
    Söderlind, Lina
    Stockholm University, Faculty of Science, Department of Zoology, Animal Ecology.
    Gamberale-Stille, Gabriella
    Stockholm University, Faculty of Science, Department of Zoology, Ethology.
    Audusseau, Hélène
    Stockholm University, Faculty of Science, Department of Zoology, Animal Ecology.
    Celorio-Mancera, Maria de la Paz
    Stockholm University, Faculty of Science, Department of Zoology, Animal Ecology.
    Janz, Niklas
    Stockholm University, Faculty of Science, Department of Zoology, Animal Ecology.
    Sperling, Felix A. H.
    Vestiges of an ancestral host plant: preference and performance in the butterfly Polygonia faunus and its sister species P. c-album2015In: Ecological Entomology, ISSN 0307-6946, E-ISSN 1365-2311, Vol. 40, no 3, p. 307-315Article in journal (Refereed)
    Abstract [en]

    1. In the study of the evolution of insect-host plant interactions, important information is provided by host ranking correspondences among female preference, offspring preference, and offspring performance. Here, we contrast such patterns in two polyphagous sister species in the butterfly family Nymphalidae, the Nearctic Polygonia faunus, and the Palearctic P. c-album. 2. These two species have similar host ranges, but according to the literature P. faunus does not use the ancestral host plant clade-the urticalean rosids'. Comparisons of the species can thus test the effects of a change in insect-plant associations over a long time scale. Cage experiments confirmed that P. faunus females avoid laying eggs on Urtica dioica (the preferred host of P. c-album), instead preferring Salix, Betula, and Ribes.3. However, newly hatched larvae of both species readily accept and grow well on U. dioica, supporting the general theory that evolutionary changes in host range are initiated through shifts in female host preferences, whereas larvae are more conservative and also can retain the capacity to perform well on ancestral hosts over long time spans.4. Similar rankings of host plants among female preference, offspring preference, and offspring performance were observed in P. c-album but not in P. faunus. This is probably a result of vestiges of larval adaptations to the lost ancestral host taxon in the latter species. 5. Female and larval preferences seem to be largely free to evolve independently, and consequently larval preferences warrant more attention.

  • 21.
    Outomuro, David
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics.
    Cordero Rivera, Adolfo
    Nava-Bolanos, Angela
    Cordoba-Aguilar, Alex
    Does allometry of a sexually selected ornamental trait vary with sexual selection intensity?: A multi-species test in damselflies2014In: Ecological Entomology, ISSN 0307-6946, E-ISSN 1365-2311, Vol. 39, no 3, p. 399-403Article in journal (Refereed)
    Abstract [en]

    <list list-type="1"> Ornaments may show hyperallometry in certain taxa, i.e. large individuals have proportionally larger ornaments than small ones. One hypothesis suggests that higher sexual selection intensity leads to steeper hyperallometric patterns. This study tested whether an ornamental trait subject to both intra- and intersexual selection showed steeper allometric slopes than when subject solely to intrasexual selection. The study employed the sexually selected male wing pigmentation of 14 calopterygid species (damselflies) that differ in sexual selection intensity (intrasexual selection versus intra- and intersexual selection). Hyperallometry was not a uniform pattern in the study species. Furthermore, the allometric slopes did not differ between sexual selection intensities. The allometry of ornamental traits is therefore highly variable even among related species. Other selection pressures-probably species-specific and at a local scale-acting on wing pigmentation might explain the diversity of allometric patterns.

  • 22.
    Rasmussen, Pil U.
    et al.
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Amin, Tarique
    Bennett, Alison E.
    Karlsson Green, Kristina
    Timonen, Sari
    Van Nouhuys, Saskya
    Tack, Ayco J. M.
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Plant and insect genetic variation mediate the impact of arbuscular mycorrhizal fungi on a natural plant-herbivore interaction2017In: Ecological Entomology, ISSN 0307-6946, E-ISSN 1365-2311, Vol. 42, no 6, p. 793-802Article in journal (Refereed)
    Abstract [en]

    1. While both arbuscular mycorrhizal (AM) fungi and plant and insect genotype are well known to influence plant and herbivore growth and performance, information is lacking on how these factors jointly influence the relationship between plants and their natural herbivores. 2. The aim of the present study was to investigate how a natural community of arbuscular mycorrhizal fungi affects the growth of the perennial herb Plantago lanceolata L. (Plantaginaceae), as well as its interaction with the Glanville fritillary butterfly [Melitaea cinxia L. (Nymphalidae)]. For this, a multifactorial experiment was conducted using plant lines originating from multiple plant populations in the angstrom land Islands, Finland, grown either with or without mycorrhizal fungi. For a subset of plant lines, the impact of mycorrhizal inoculation, plant line, and larval family on the performance of M. cinxia larvae were tested. 3. Arbuscular mycorrhizal inoculation did not have a consistently positive or negative impact on plant growth or herbivore performance. Instead, plant genetic variation mediated the impact of arbuscular mycorrhizal fungi on plant growth, and both plant genetic variation and herbivore genetic variation mediated the response of the herbivore. For both the plant and insect, the impact of the arbuscular mycorrhizal community ranged from mutualistic to antagonistic. Overall, the present findings illustrate that genetic variation in response to mycorrhizal fungi may play a key role in the ecology and evolution of plant-insect interactions.

  • 23.
    Roubinet, Eve
    et al.
    Department of Ecology, Swedish University of Agricultural Sciences, Uppsala, Sweden.
    Straub, Cory
    Biology Department, Ursinus College, Collegeville, Pennsylvania, U.S.A.
    Jonsson, Tomas
    Department of Ecology, Swedish University of Agricultural Sciences, Uppsala, Sweden.
    Staudacher, Karin
    Mountain Agriculture Research Unit, Institute of Ecology, University of Innsbruck, Innsbruck, Austria.
    Traugott, Michael
    Mountain Agriculture Research Unit, Institute of Ecology, University of Innsbruck, Innsbruck, Austria.
    Ekbom, Barbara
    Department of Ecology, Swedish University of Agricultural Sciences, Uppsala, Sweden.
    Jonsson, Mattias
    Department of Ecology, Swedish University of Agricultural Sciences, Uppsala, Sweden.
    Additive effects of predator diversity on pest control caused by few interactions among predator species2015In: Ecological Entomology, ISSN 0307-6946, E-ISSN 1365-2311, Vol. 40, no 4, p. 362-371Article in journal (Refereed)
  • 24.
    Slove, Jessica
    et al.
    Stockholm University, Faculty of Science, Department of Zoology, Animal Ecology.
    Janz, Niklas
    Stockholm University, Faculty of Science, Department of Zoology, Animal Ecology.
    Phylogenetic analysis of the latitude-niche breadth hypothesis in the butterfly subfamily Nymphalinae2010In: Ecological Entomology, ISSN 0307-6946, E-ISSN 1365-2311, Vol. 35, no 6, p. 768-774Article in journal (Refereed)
    Abstract [en]

    One possible explanation for the latitudinal gradient in species richness often demonstrated is a related gradient in niche breadth, which may allow for denser species packing in the more stable environments at low latitudes.

    The evidence for such a gradient is, however, ambiguous, and the results have varied as much as the methods. Several studies have considered the non-independence of species, but few have performed explicit phylogenetic analyses.

    In the present study, we tested for a correlation between diet breadth and latitude of distribution in Nymphalinae butterflies using generalised estimating equations (GEE) and accounting for phylogenetic independence.

    Using a simple model with only latitude of distribution as a predictor variable revealed a significant positive relationship with diet breadth. Previous studies, however, have shown that diet breadth is also correlated with butterfly range size, and in turn, that range size may be correlated with latitude of distribution. Including geographical range size in the model also turned out to have a profound effect on the results – to the extent that the relationship between latitude of distribution and diet breadth was effectively reversed.

    We conclude that, at least for this group of butterflies, there is no evidence for a positive correlation between latitude of species distribution and diet breadth when controlling for range size, and that the effect may actually even be reversed.

  • 25. Sniegula, Szymon
    et al.
    Drobniak, Szymon M.
    Golab, Maria J.
    Johansson, Frank
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Animal ecology.
    Photoperiod and variation in life history traits in core and peripheral populations in the damselfly Lestes sponsa2014In: Ecological Entomology, ISSN 0307-6946, E-ISSN 1365-2311, Vol. 39, no 2, p. 137-148Article in journal (Refereed)
    Abstract [en]

    In order to predict evolutionary responses to environmental changes one needs to identify the evolutionary potential in terms of genetic variation of traits and of the traits' plasticity. We studied genetic variance in life history traits and their reaction norms in response to manipulated photoperiods in central, northern, and northernmost peripheral populations of the damselfly Lestes sponsa (Hansemann). After the central-marginal hypothesis, it is predicted that central populations will express the highest genetic variance. Northern and northernmost populations showed the highest development and growth rates. All populations expressed shorter development and accelerated growth when raised in a northern compared with a central latitude photoperiod. The slopes of reaction norms differed between regions resulting in a region-by-photoperiod interaction. There was genetic variation in development time; however, it did not differ across regions. There was no genetic variation in growth rate or in the plasticity of development time and growth rate to photoperiod. Results did not support the central-marginal hypothesis. However, evidence was found that the development time has the potential to evolve at similar rates across study regions. In contrast, the growth rate seems to be genetically constrained for further evolution, probably because of a strong past directional selection on this trait. The presence of low genetic variation in the slope of the reaction norms could be a result of stabilising selection imposed by seasonality.

  • 26.
    Sniegula, Szymon
    et al.
    Polish Acad Sci, Inst Nat Conservat, Dept Ecosyst Conservat, Krakow, Poland..
    Golab, Maria J.
    Polish Acad Sci, Inst Nat Conservat, Dept Ecosyst Conservat, Krakow, Poland..
    Johansson, Frank
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Animal ecology.
    A large-scale latitudinal pattern of life-history traits in a strictly univoltine damselfly2016In: Ecological Entomology, ISSN 0307-6946, E-ISSN 1365-2311, Vol. 41, no 4, p. 459-472Article in journal (Refereed)
    Abstract [en]

    1. Variation in thermal conditions and season length along latitudinal gradients affect body size-related traits over different life stages. Selection is expected to optimise these size traits in response to the costs and benefits. 2. Egg, hatchling, larval and adult size in males and females were estimated along a latitudinal gradient of 2730km across Europe in the univoltine damselfly Lestes sponsa, using a combination of field-collection and laboratory-rearing experiments. In the laboratory, individuals were grown in temperatures and photoperiod simulating those at the latitude of origin, and in common-garden conditions. 3. The size of adults sampled in nature was negatively correlated with latitude. In all populations the females were larger than the males. Results from simulated and common-garden rearing experiments supported this pattern of size difference across latitudes and between sexes, suggesting a genetic component for the latitudinal size trend and female-biased size dimorphism. In contrast, hatchling size showed a positive relationship with latitude, but egg size, although differing between latitudes, showed no such relationship. 4. The results support a converse Bergmann cline, i.e. a negative body size cline towards the north. This negative cline in body size is probably driven by progressively stronger seasonal time and temperature constraints towards the higher latitudes and by the obligate univoltine life cycle of L. sponsa. As egg size showed no relationship with latitude, other environmental factors besides temperature, such as desiccation risk, probably affect this trait.

  • 27. Sniegula, Szymon
    et al.
    Johansson, Frank
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Photoperiod affects compensating developmental rate across latitudes in the damselfly Lestes sponsa2010In: Ecological Entomology, ISSN 0307-6946, E-ISSN 1365-2311, Vol. 35, no 2, p. 149-157Article in journal (Refereed)
    Abstract [en]

    1. Although there is a great deal of theoretical and empirical data about the life history responses of time constraints in organisms, little is known about the latitude-compensating mechanism that enables northern populations' developmental rates to compensate for latitude. To investigate the importance of photoperiod on development, offspring of the obligatory univoltine damselfly Lestes sponsa from two populations at different latitudes (53°N and 63°N) were raised in a common laboratory environment at both northern and southern photoperiods that corresponded to the sites of collection.

    2. Egg development time was shorter under northern photoperiod regimes for both populations. However, the northern latitude population showed a higher phenotypic plasticity response to photoperiod compared with the southern latitude population, suggesting a genetic difference in egg development time in response to photoperiod.

    3. Larvae from both latitudes expressed shorter larval development time and faster growth rates under northern photoperiod regimes. There was no difference in phenotypic plastic response between northern and southern latitude populations with regard to development time.

    4. Data on field collected adults showed that adult sizes decreased with an increase in latitude. This adult size difference was a genetically fixed trait, as the same size difference between populations was also found when larvae were reared in the laboratory.

    5. The results suggest phenotypic plasticity responses in life history traits to photoperiod, but also genetic differences between north and south latitude populations in response to photoperiod, which indicates the presence of a latitudinal compensating mechanism that is triggered by a photoperiod.

  • 28. Sniegula, Szymon
    et al.
    Prus, Monika A.
    Golab, Maria J.
    Outomuro, David
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Animal ecology.
    Do males with higher mating success invest more in armaments?: An across-populations study in damselflies2017In: Ecological Entomology, ISSN 0307-6946, E-ISSN 1365-2311, Vol. 42, no 4, p. 526-530Article in journal (Refereed)
    Abstract [en]

    1. Males with higher mating success would be expected to invest more in traits that facilitate mating, leading to steeper allometry of those traits with respect to body size. Across-population studies following latitudinal variation in male mating success are an excellent study system to address this question.

    2. Males of the damselfly Lestes sponsa were used to investigate whether the allometric patterns of the length and width of the anal appendages, used for grasping the female prior tomating, corresponded to male mating success. Across a large latitudinal gradient, it was hypothesised that there is a larger investment in the grasping apparatus, i.e. a steeper allometric slope, following higher mating success.

    3. Behavioural observations in field enclosures showed the highest mating success at high latitude, while there were no significant differences in mating success between the central and low latitudes. Positive allometry was found for the length of the anal appendages in high-latitude males, while central-and low-latitude males showed no significant regressions of the traits on body size.

    4. These results partially support the hypothesis, as high-latitude, more successful males invested more in the length ( but not the width) of the grasping apparatus than did central-and low-latitude males. Therefore, higher mating success might be facilitated by larger investment in armaments. Intraspecific studies on allometric patterns of traits that participate in mating success might offer new insights into the role of those traits in the reproductive behaviour of a species.

  • 29.
    Tegelaar, Karolina
    et al.
    Stockholm University, Faculty of Science, Department of Zoology.
    Leimar, Olof
    Stockholm University, Faculty of Science, Department of Zoology.
    Alate production in an aphid in relation to ant tending and alarm pheromone2014In: Ecological Entomology, ISSN 0307-6946, E-ISSN 1365-2311, Vol. 39, no 5, p. 664-666Article in journal (Refereed)
    Abstract [en]

    1. Winged dispersal is vital for aphids as predation pressure and host plant conditions fluctuate. 2. Ant-tended aphids also need to disperse, but this may represent a cost for the ants, resulting in an evolutionary conflict of interest over aphid dispersal. 3. The combined effects of aphid alarm pheromone, indicating predation risk, and ant attendance on the production of winged aphids were examined in an experiment with Aphis fabae (Homoptera: Aphididae) (Scopoli 1763) aphids and Lasius niger (Formicidae: Formicinae) (Linne, 1758) ants. 4. This study is the first to investigate the joint effects of alarm pheromone and ant attendance, and also the first to detect an influence of alarm pheromone on the production of winged morphs in A. fabae. 5. After a period of 2 weeks, it was found that aphid colonies exposed to intermittent doses of alarm pheromone produced more winged individuals, whereas ant tending had the opposite effect. The effects were additive on a log scale, and ant attendance had a greater proportional influence than exposure to alarm pheromone. A tentative conclusion is that ants have gained the upper hand in an evolutionary conflict about aphid dispersal.

  • 30.
    Victorsson, Jonas
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Animal Ecology.
    Semi-field experiments investigating facilitation: arrival order decides the interrelationship between two saproxylic beetle species2012In: Ecological Entomology, ISSN 0307-6946, E-ISSN 1365-2311, Vol. 37, no 5, p. 395-401Article in journal (Refereed)
    Abstract [en]

    1. Acanthocinus aedilis (Linnaeus) and Rhagium inquisitor (Linnaeus) both colonise the cambial layer in newly dead Scots pine Pinus sylvestris L. and thus are potential competitors. 2. Species interactions and in particular priority effects were investigated in an experiment with a replacement series design. Four pairs of adult beetles were released on each of 91 caged pine bolts (0.35 m long, 13 replicates). To test for priority effects, a 2-week interval was used to separate the species. 3. The interrelationship in simultaneous coexistence was positive for A. aedilis and negative for R. inquisitor (+,-). Acanthocinus aedilis produced 161% more offspring per female in coexistence than alone. Rhagium inquisitor had lower offspring quality in coexistence where its larvae weighed 39% less than in one-species bolts. 4. The interrelationship depended on arrival order. When A. aedilis had priority the interaction was again advantageous to A. aedilis (+,-) but when R. inquisitor had priority no species interaction occurred (0,0). Both species therefore fared better when having priority. 5. Facilitation in cerambycids is novel and the facilitative effect on A. aedilis could be oviposition incitement or resource enhancement by R. inquisitor.

  • 31.
    Wiklund, Christer
    et al.
    Stockholm University, Faculty of Science, Department of Zoology.
    Stefanescu, Contanti
    Friberg, Magne
    Host plant exodus and larval wandering behaviour in a butterfly: diapause generation larvae wander for longer periods than do non-diapause generation larvae2017In: Ecological Entomology, ISSN 0307-6946, E-ISSN 1365-2311, Vol. 42, no 4, p. 531-534Article in journal (Refereed)
    Abstract [en]

    1. Prior to pupation, lepidopteran larvae enter a wandering phase lasting up to 30 h before choosing a pupation site. Because stillness is important for concealment, this behaviour calls for an adaptive explanation. 2. The explanation most likely relates to the need to find a suitable pupation substrate, especially in terms of shelter from predation, and given that many predators and parasitoids use host plants as prey-location cues, mortality probably decreases with distance from the host plant. Hence, remaining on the host includes a long-term risk, while moving away from the host introduces an increased risk during locomotion. 3. Bivoltine species that overwinter in the pupal stage produce two kinds of pupae; non-diapausing pupae from which adults emerge after 1-2 weeks, or diapausing pupae that overwinter with adults emerging after 8-10 months. 4. Given the hypothesis of distance-from-host-plant-related predation, this should select for phenotypic plasticity with larvae in the diapausing generation having a longer wandering phase than larvae under direct development, if there is a trade-off between mortality during the wandering phase and accumulated mortality during winter. 5. Here this prediction is tested by studying the duration of the wandering period in larvae of the partially bivoltine swallowtail butterfly, Papilio machaon, under both developmental pathways. 6. The results are in agreement with the predictions and show that the larval wandering phase is approximately twice as long under diapause development. The authors suggest that the longer duration of the wandering phase in the diapause generation is a general phenomenon in Lepidoptera.

  • 32.
    Wiklund, Christer
    et al.
    Stockholm Univ, Dept Zool, SE-10691 Stockholm, Sweden..
    Stefanescu, Contanti
    Nat Hist Museum Granollers, Granollers, Spain.;CREAF, Cerdanyola Del Valles, Spain..
    Friberg, Magne
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Plant Ecology and Evolution.
    Host plant exodus and larval wandering behaviour in a butterfly: diapause generation larvae wander for longer periods than do non-diapause generation larvae2017In: Ecological Entomology, ISSN 0307-6946, E-ISSN 1365-2311, Vol. 42, no 4, p. 531-534Article in journal (Refereed)
    Abstract [en]

    1. Prior to pupation, lepidopteran larvae enter a wandering phase lasting up to 30 h before choosing a pupation site. Because stillness is important for concealment, this behaviour calls for an adaptive explanation.

    2. The explanation most likely relates to the need to find a suitable pupation substrate, especially in terms of shelter from predation, and given that many predators and parasitoids use host plants as prey-location cues, mortality probably decreases with distance from the host plant. Hence, remaining on the host includes a long-term risk, while moving away from the host introduces an increased risk during locomotion.

    3. Bivoltine species that overwinter in the pupal stage produce two kinds of pupae; non-diapausing pupae from which adults emerge after 1-2 weeks, or diapausing pupae that overwinter with adults emerging after 8-10 months.

    4. Given the hypothesis of distance-from-host-plant-related predation, this should select for phenotypic plasticity with larvae in the diapausing generation having a longer wandering phase than larvae under direct development, if there is a trade-off between mortality during the wandering phase and accumulated mortality during winter.

    5. Here this prediction is tested by studying the duration of the wandering period in larvae of the partially bivoltine swallowtail butterfly, Papilio machaon, under both developmental pathways.

    6. The results are in agreement with the predictions and show that the larval wandering phase is approximately twice as long under diapause development. The authors suggest that the longer duration of the wandering phase in the diapause generation is a general phenomenon in Lepidoptera.

  • 33.
    Åhman, Mikael
    et al.
    Stockholm University, Faculty of Science, Department of Zoology.
    Karlsson, Bengt
    Stockholm University, Faculty of Science, Department of Zoology, Animal Ecology.
    Flight endurance in relation to adult age in the green-veined white butterfly Pieris napi2009In: Ecological Entomology, ISSN 0307-6946, E-ISSN 1365-2311, Vol. 34, p. 783-787Article in journal (Refereed)
    Abstract [en]

    Abstract. 1. The flight apparatus in butterflies as well as in other insects is costly to manufacture. Since most animals live in a world where resources are limited, trade-offs are expected and available resources must thus be allocated between flight and other functions such as reproduction.

    2. To mitigate this trade-off, previous studies have shown that butterflies can break down flight muscles in the thorax as they age in order to use muscle nutrients for reproduction.

    3. Although breakdown of flight muscles is expected to reduce flight ability, relative flight muscle ratio (thorax mass/body mass) in many butterfly species does not decrease with age.  Our aim in this study was to test the relationship between flight endurance and adult age in the green-veined white butterfly Pieris napi (L.). The tests were performed in the laboratory under five different temperatures.

    4. The results showed that age has a significant influence on butterfly flight endurance; older butterflies showed reduced flight endurance. Male butterflies fly for a longer time than females and flight endurance increase with temperature in both sexes.

1 - 33 of 33
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