For capital-breeding insects,all resources available for adult metabolic needs are accumulated during larval feeding.Therefore,body size at adult eclosion represents the total energetic capacity of the individual.For ...For capital-breeding insects,all resources available for adult metabolic needs are accumulated during larval feeding.Therefore,body size at adult eclosion represents the total energetic capacity of the individual.For female capital breeders,body size is strongly correlated with lifetime fecundity,while in males,body size,which correlates with fitness,is less understood.In capital-breeding species with wingless,flightless,or dispersal-limited females,flight potential for male Lepidoptera has important implications for mate-finding and may be correlated with body size.At low population densities,failure to mate has been identified as an important Allee effect and can drive the success or failure of invasive species at range edges and in species of conservation concern.Th capital-breeding European subspecies of Lymantria dispar(L.),was introduced to North America in 1869 and now ranges across much of eastern North America.In L.dispar,females are flightless and mate-finding is entirely performed by males.We quantified male L.dispar flight capacity and propensity relative to morphological and physiological characteristics using fixed-arm flight mills.A range of male body sizes was produced by varying the protein content of standard artificial diets while holding other dietary components constant.Wing length,a proxy for body size,relative thorax mass,and forewing aspect were all important predictors of total flight distance and maximum speed.These results have important implications for mate-finding and invasion dynamics in L.dispar and may apply broadly to other capital-breeding insects.展开更多
Under global climate change,high and low temperature extremes can drive shifts in species distributions.Across the range of a species,thermal tolerance is based on acclimatization,plasticity,and may undergo selection,...Under global climate change,high and low temperature extremes can drive shifts in species distributions.Across the range of a species,thermal tolerance is based on acclimatization,plasticity,and may undergo selection,shaping resilience to temperature stress.In this study,we measured variation in cold temperature tolerance of early instar larvae of an invasive forest insect,Lymantria dispar dispar L.(Lepidoptera:Erebidae),using populations sourced from a range of climates within the current introduced range in the Eastern United States.We tested for population differences in chill coma recovery(CCR)by measuring recovery time following a period of exposure to a nonlethal cold temperature in 2 cold exposure experiments.A 3rd experiment quantified growth responses after CCR to evaluate sublethal effects.Our results indicate that cold tolerance is linked to regional climate,with individuals from populations sourced from colder climates recovering faster from chill coma.While this geographic gradient is seen in many species,detecting this pattern is notable for an introduced species founded from a single point-source introduction.We demonstrate that the cold temperatures used in our experiments occur in nature during cold spells after spring egg hatch,but impacts to growth and survival appear low.We expect that population differences in cold temperature performance manifest more from differences in temperature-dependent growth than acute exposure.Evaluating intraspecific variation in cold tolerance increases our understanding of the role of climatic gradients on the physiology of an invasive species,and contributes to tools for predicting further expansion.展开更多
American chestnut(Castanea dentata[Marsh.]Borkh.)was once the dominant hardwood species in Eastern North America before an exotic fungal pathogen,Cryphonec-tria parasitica(Murrill)Barr,functionally eliminated it acros...American chestnut(Castanea dentata[Marsh.]Borkh.)was once the dominant hardwood species in Eastern North America before an exotic fungal pathogen,Cryphonec-tria parasitica(Murrill)Barr,functionally eliminated it across its range.One promising approach toward restoring American chestnut to natural forests is development of blight-tolerant trees using genetic transformation.However,transformation and related processes can result in unexpected and unintended phenotypic changes,potentially altering ecologi-cal interactions.To assess unintended tritrophic impacts of transgenic American chestnut on plant herbivore interactions,gypsy moth(Lymantria dispar L.)caterpillars were fed leaf disks excised from two transgenic events,Darling 54 and Darling 58,and four control American chestnut lines.Leaf disks were previously treated with an LDso dose of either the speces-specific Lymantria dispar multiple nucleopolyhedrovirus(LdMNPV)or the generalist pathogen Bacillus thuringiensis subsp.kurstaki(Btk).Mortality was quantified and compared to water blank controls.Tree genotype had a strong efect on the efficacies of both pathogens.Larval mortality from Btk-treated foliage from only one transgenic event,Darling 54,differed from its isogenic progenitor,Ellis l,but was similar to an unre-lated wild-type American chestnut control.LdMNPV efficacy was unaffected by genetic transformation.Results suggest that although genetic modification of trees may affect interactions with other nontarget organisms,this may be due to insertion effects,and varia-tion amnon diMterent genvtypes(wlether uasgeic ul wild-typc)iupaults a giealci change in response than transgene presence.展开更多
基金Funding was provided by Macrosystems Biology(Grant 1702701 to Kristine Grayson,Sal Agosta,and Dylan Parry)Gypsy Moth Slow-the-Spread Foundation,Inc(Grant 19-01-13 to DP).
文摘For capital-breeding insects,all resources available for adult metabolic needs are accumulated during larval feeding.Therefore,body size at adult eclosion represents the total energetic capacity of the individual.For female capital breeders,body size is strongly correlated with lifetime fecundity,while in males,body size,which correlates with fitness,is less understood.In capital-breeding species with wingless,flightless,or dispersal-limited females,flight potential for male Lepidoptera has important implications for mate-finding and may be correlated with body size.At low population densities,failure to mate has been identified as an important Allee effect and can drive the success or failure of invasive species at range edges and in species of conservation concern.Th capital-breeding European subspecies of Lymantria dispar(L.),was introduced to North America in 1869 and now ranges across much of eastern North America.In L.dispar,females are flightless and mate-finding is entirely performed by males.We quantified male L.dispar flight capacity and propensity relative to morphological and physiological characteristics using fixed-arm flight mills.A range of male body sizes was produced by varying the protein content of standard artificial diets while holding other dietary components constant.Wing length,a proxy for body size,relative thorax mass,and forewing aspect were all important predictors of total flight distance and maximum speed.These results have important implications for mate-finding and invasion dynamics in L.dispar and may apply broadly to other capital-breeding insects.
基金conducted under USDA APHIS permit numbers P526P-17-03681 and P526P-20-02026(K.L.G.)and P526P-16-04388(D.P.)supported by the National Science Foundation under Grant DEB 1702701(K.L.G.)and 1702312(D.P.)under the Macrosystems Biology Program and the Thomas F.and Kate Miller Jeffress Memorial Trust+1 种基金funding was provided by the Slow-the-Spread Foundationthe University of Richmond School of Arts&Sciences.
文摘Under global climate change,high and low temperature extremes can drive shifts in species distributions.Across the range of a species,thermal tolerance is based on acclimatization,plasticity,and may undergo selection,shaping resilience to temperature stress.In this study,we measured variation in cold temperature tolerance of early instar larvae of an invasive forest insect,Lymantria dispar dispar L.(Lepidoptera:Erebidae),using populations sourced from a range of climates within the current introduced range in the Eastern United States.We tested for population differences in chill coma recovery(CCR)by measuring recovery time following a period of exposure to a nonlethal cold temperature in 2 cold exposure experiments.A 3rd experiment quantified growth responses after CCR to evaluate sublethal effects.Our results indicate that cold tolerance is linked to regional climate,with individuals from populations sourced from colder climates recovering faster from chill coma.While this geographic gradient is seen in many species,detecting this pattern is notable for an introduced species founded from a single point-source introduction.We demonstrate that the cold temperatures used in our experiments occur in nature during cold spells after spring egg hatch,but impacts to growth and survival appear low.We expect that population differences in cold temperature performance manifest more from differences in temperature-dependent growth than acute exposure.Evaluating intraspecific variation in cold tolerance increases our understanding of the role of climatic gradients on the physiology of an invasive species,and contributes to tools for predicting further expansion.
基金Thanks to Hannah Nadel(USDA-APHIS)for kindly providing gypsy moth larvae,and John Podgwaite(USDA Forest Service)for providing purified LdM-NPV.We gratefully acknowledge Seaira Goetz and Elliot Hunsinger for their outstanding technical assistance in the laboratory.Substantive comments by T.Horton and M.K.Fierke improved earlier versions of the manuscript.This project was supported by Biotechnology Risk Assessment Grant Program competitive grant No.2012-33522-19863 from the USDA National Institute of Food and.Agriculture.
文摘American chestnut(Castanea dentata[Marsh.]Borkh.)was once the dominant hardwood species in Eastern North America before an exotic fungal pathogen,Cryphonec-tria parasitica(Murrill)Barr,functionally eliminated it across its range.One promising approach toward restoring American chestnut to natural forests is development of blight-tolerant trees using genetic transformation.However,transformation and related processes can result in unexpected and unintended phenotypic changes,potentially altering ecologi-cal interactions.To assess unintended tritrophic impacts of transgenic American chestnut on plant herbivore interactions,gypsy moth(Lymantria dispar L.)caterpillars were fed leaf disks excised from two transgenic events,Darling 54 and Darling 58,and four control American chestnut lines.Leaf disks were previously treated with an LDso dose of either the speces-specific Lymantria dispar multiple nucleopolyhedrovirus(LdMNPV)or the generalist pathogen Bacillus thuringiensis subsp.kurstaki(Btk).Mortality was quantified and compared to water blank controls.Tree genotype had a strong efect on the efficacies of both pathogens.Larval mortality from Btk-treated foliage from only one transgenic event,Darling 54,differed from its isogenic progenitor,Ellis l,but was similar to an unre-lated wild-type American chestnut control.LdMNPV efficacy was unaffected by genetic transformation.Results suggest that although genetic modification of trees may affect interactions with other nontarget organisms,this may be due to insertion effects,and varia-tion amnon diMterent genvtypes(wlether uasgeic ul wild-typc)iupaults a giealci change in response than transgene presence.
