Understanding the thermal dynamics of host-parasitoid interactions is crucial to predicting how biological control of pest insects by parasitoids might be affected by geographic location and climate change.We compared...Understanding the thermal dynamics of host-parasitoid interactions is crucial to predicting how biological control of pest insects by parasitoids might be affected by geographic location and climate change.We compared performance traits of Plutella xylostella(Lepidoptera:Plutellidae)and its solitary endo-larval parasitoid Diadegma semiclausum(Hymenoptera:Ichneumonidae),over a wide range of constant rearing temperatures(10-30℃).Parasitoids reared at 30℃ experienced reductions in pupation rate,pupal mass,egg load,and adult life span when compared with those reared at lower temperatures.Our analyses of the fate of parasitoids and their hosts and intergenerational population growth at different rearing temperatures show that D.semiclausum and P.xylostella respond differently to temperature,leading to divergent outcomes under different temperature conditions.Some parasitoid larvae could not complete development at 30℃,the temperature at which the host biomass was least and the metabolic demands of the parasitoid could be high,suggesting that parasitoid development might be constrained by lack of host resources at higher temperatures.We discuss the potential mechanisms of parasitoid susceptibility to elevated temperatures,which likely explain the pronounced seasonal dynamics of D.semiclausum in subtropical regions and its failure to establish in lowland tropical regions,where P.xylostella is a serious pest.Similar interactions in other host-parasitoid associations would constrain the efficacy of parasitoids as biological control agents as global temperatures increase.展开更多
Rapid learning in the young of most endothermic animals can be expected to be favored by natural selection because early independence reduces the period of vulnerability.Cases of comparatively slow juvenile developmen...Rapid learning in the young of most endothermic animals can be expected to be favored by natural selection because early independence reduces the period of vulnerability.Cases of comparatively slow juvenile development continue,therefore,to attract scientific attention.In most species of birds,including raptors,the young depend on their parents for some time after fledging for the provisioning of food and for protection while they learn to become nutritionally and otherwise independent.Among raptors,post-fledging dependence periods that exceed 6 months are exclusive to the largest species and these have reproductive cycles that exceed 12 months.By contrast,young of the medium-sized grey falcon Falco hypoleucos have been reported in close company with their parents up to 12 months after fledging,that is,at a time when the adults are expected to breed again.We investigated the occurrence and characteristics of prolonged adult–juvenile association relative to other falcons and similar-sized raptors.We found that the behavioral development of grey falcon young is extremely delayed,and that they even depend nutritionally on their parents for up to 12 months after fledging.We suggest that these 2 distinctive features are,ultimately,adaptations of the grey falcon to its extreme environment,Australia’s arid and semi-arid zone,one of the hottest environments in the world.展开更多
To survive in nature,organisms may need to take direct action to mitigate specific dangers from their environmental surroundings.Tiny flying insects are thought to be at particular risk from rainfall that would be of ...To survive in nature,organisms may need to take direct action to mitigate specific dangers from their environmental surroundings.Tiny flying insects are thought to be at particular risk from rainfall that would be of negligible concern to larger animals.The study species Frankliniella schultzei is a thrips that inhabits flowers and feeds mostly on petal tissue and pollen.While found to respond in the laboratory to decreases in atmospheric pressure associated with cyclonic conditions (rather than merely heavy rainfall),their responses to conditions preceding rainfall have not been tested in the field.Initial field sampling investigated the relationship between floral development and sites at which male,female,and larval thrips were generally present on sunny days.We then designed a sampling strategy to test if these thrips can anticipate imminent rainfall or storms and so seek shelter deep within flowers,by sampling host flowers (in sections)on multiple days with different weather conditions.Sticky traps were used to intercept thrips in flight,thus providing a measure of flight behavior across different days.The initial sampling found adult thrips primarily at the petal apex of anthesis-stage flowers where pollen is distributed. We subsequently found that rainfall,atmospheric pressure change,temperature,humidity and wind had no effect on flight behavior of E schultzei,or on their positions within flowers.These findings suggest rainfall is not a serious hazard for them.Perhaps thrips can survive raindrop collisions during flight,as impacts with water droplets are not expected to break the surface tension.展开更多
基金This project is funded in part by Australian Centre for International Agricultural Research project HORT/2016/185.
文摘Understanding the thermal dynamics of host-parasitoid interactions is crucial to predicting how biological control of pest insects by parasitoids might be affected by geographic location and climate change.We compared performance traits of Plutella xylostella(Lepidoptera:Plutellidae)and its solitary endo-larval parasitoid Diadegma semiclausum(Hymenoptera:Ichneumonidae),over a wide range of constant rearing temperatures(10-30℃).Parasitoids reared at 30℃ experienced reductions in pupation rate,pupal mass,egg load,and adult life span when compared with those reared at lower temperatures.Our analyses of the fate of parasitoids and their hosts and intergenerational population growth at different rearing temperatures show that D.semiclausum and P.xylostella respond differently to temperature,leading to divergent outcomes under different temperature conditions.Some parasitoid larvae could not complete development at 30℃,the temperature at which the host biomass was least and the metabolic demands of the parasitoid could be high,suggesting that parasitoid development might be constrained by lack of host resources at higher temperatures.We discuss the potential mechanisms of parasitoid susceptibility to elevated temperatures,which likely explain the pronounced seasonal dynamics of D.semiclausum in subtropical regions and its failure to establish in lowland tropical regions,where P.xylostella is a serious pest.Similar interactions in other host-parasitoid associations would constrain the efficacy of parasitoids as biological control agents as global temperatures increase.
基金This work was supported by the Dampier Bunbury Pipeline,Perth,Western AustraliaThe Peregrine Fund,Boise IDthe Department of Biodiversity,Conservation and Attractions,Western Australia.J.S.was supported by the Australian Government Research Training Program Scholarship.
文摘Rapid learning in the young of most endothermic animals can be expected to be favored by natural selection because early independence reduces the period of vulnerability.Cases of comparatively slow juvenile development continue,therefore,to attract scientific attention.In most species of birds,including raptors,the young depend on their parents for some time after fledging for the provisioning of food and for protection while they learn to become nutritionally and otherwise independent.Among raptors,post-fledging dependence periods that exceed 6 months are exclusive to the largest species and these have reproductive cycles that exceed 12 months.By contrast,young of the medium-sized grey falcon Falco hypoleucos have been reported in close company with their parents up to 12 months after fledging,that is,at a time when the adults are expected to breed again.We investigated the occurrence and characteristics of prolonged adult–juvenile association relative to other falcons and similar-sized raptors.We found that the behavioral development of grey falcon young is extremely delayed,and that they even depend nutritionally on their parents for up to 12 months after fledging.We suggest that these 2 distinctive features are,ultimately,adaptations of the grey falcon to its extreme environment,Australia’s arid and semi-arid zone,one of the hottest environments in the world.
文摘To survive in nature,organisms may need to take direct action to mitigate specific dangers from their environmental surroundings.Tiny flying insects are thought to be at particular risk from rainfall that would be of negligible concern to larger animals.The study species Frankliniella schultzei is a thrips that inhabits flowers and feeds mostly on petal tissue and pollen.While found to respond in the laboratory to decreases in atmospheric pressure associated with cyclonic conditions (rather than merely heavy rainfall),their responses to conditions preceding rainfall have not been tested in the field.Initial field sampling investigated the relationship between floral development and sites at which male,female,and larval thrips were generally present on sunny days.We then designed a sampling strategy to test if these thrips can anticipate imminent rainfall or storms and so seek shelter deep within flowers,by sampling host flowers (in sections)on multiple days with different weather conditions.Sticky traps were used to intercept thrips in flight,thus providing a measure of flight behavior across different days.The initial sampling found adult thrips primarily at the petal apex of anthesis-stage flowers where pollen is distributed. We subsequently found that rainfall,atmospheric pressure change,temperature,humidity and wind had no effect on flight behavior of E schultzei,or on their positions within flowers.These findings suggest rainfall is not a serious hazard for them.Perhaps thrips can survive raindrop collisions during flight,as impacts with water droplets are not expected to break the surface tension.
