The nutritional physiology of the diamondback moth, Plutella xylostella, larvae was examined after parasitization by the solitary endoparasitoids Cotesia vestalis or Diadegma semiclausum. Examinations were performed i...The nutritional physiology of the diamondback moth, Plutella xylostella, larvae was examined after parasitization by the solitary endoparasitoids Cotesia vestalis or Diadegma semiclausum. Examinations were performed in two phases, one was examined at the time point of 24 h post-parasitization, and the other was done at the end of the 4th instar larvae of host. Rates of growth, food consumption, assimilation, excretion, and respiration were calculated as well as approximate digestibility and the rate ratios ECI （percent efficiency of conversion of ingested food to body substance）, and ECD （percent efficiency of conversion of digested food to body substance）. Parasitization by C. vestalis resulted in significant decrease in the rates of growth, feeding, excretion, assimilation, and respiration, but the final dry rate of respiration at the end of last larval stadium was elevated. The ECI and ECD were also reduced as the result of parasitization, but digestibility was increased. All these parameters in the larvae parasitized by D. semiclausum at 24 h post-parasitization were also significantly changed compared to the control; however, these differences were quantitatively, but not qualitatively before pupation, similar to those resulted from parasitization by C. vestalis. In spite of the similarities of the parasitism-induced effects caused by these endoparasitoids, the final metabolic rate, that is, the rate of intake of nutrients required to compensate for metabolism, was much lower in the larvae parasitized by C. vestalis than that of the larvae parasitized by D. semiclausum. All of the results discussed here will contribute toward explaining the different ways these two wasps regulate the parasitoid-host relationship.展开更多
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
基金Funding for this study was provided jointly by 973 Program （2006CB 102005）, Key Program of Natural Science Foundation of Zhejiang Province （Z306031）, National Science Funds for Distinguished Young Scholars （Grant No. 30625006）, Program for New Century Excellent Talents in University （NCET-04-0521）, Innovation Research Team Program of the Ministry of Education of China （IRT0355）, and the China Postdoctoral Science Foundation （20060400322）.
文摘The nutritional physiology of the diamondback moth, Plutella xylostella, larvae was examined after parasitization by the solitary endoparasitoids Cotesia vestalis or Diadegma semiclausum. Examinations were performed in two phases, one was examined at the time point of 24 h post-parasitization, and the other was done at the end of the 4th instar larvae of host. Rates of growth, food consumption, assimilation, excretion, and respiration were calculated as well as approximate digestibility and the rate ratios ECI （percent efficiency of conversion of ingested food to body substance）, and ECD （percent efficiency of conversion of digested food to body substance）. Parasitization by C. vestalis resulted in significant decrease in the rates of growth, feeding, excretion, assimilation, and respiration, but the final dry rate of respiration at the end of last larval stadium was elevated. The ECI and ECD were also reduced as the result of parasitization, but digestibility was increased. All these parameters in the larvae parasitized by D. semiclausum at 24 h post-parasitization were also significantly changed compared to the control; however, these differences were quantitatively, but not qualitatively before pupation, similar to those resulted from parasitization by C. vestalis. In spite of the similarities of the parasitism-induced effects caused by these endoparasitoids, the final metabolic rate, that is, the rate of intake of nutrients required to compensate for metabolism, was much lower in the larvae parasitized by C. vestalis than that of the larvae parasitized by D. semiclausum. All of the results discussed here will contribute toward explaining the different ways these two wasps regulate the parasitoid-host relationship.
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.
