Trichogramma brassicae(Bezdenko)is an important biological control agent that has been used widely against many lepidopteran pests.Commonly,colonies of Trichogramma are mass reared on factitious hosts such as Sitotrog...Trichogramma brassicae(Bezdenko)is an important biological control agent that has been used widely against many lepidopteran pests.Commonly,colonies of Trichogramma are mass reared on factitious hosts such as Sitotroga cerealella(Olivier)over many generations.In this study,we evaluated the quality and performance of a colony of T.brassicae that had been reared for over 45 generations(G)using two-sex life table parameters and parasitism capacity.We found that female adult longevity was significantly different among sequential generations,ranging from 5.58±2.5 d(at G5)to 3.75±1.42 d(at G45).However,no significant difference was found in male adult longevity among different generations.Although female wasps survived longer until the 15th gener・ation,they allocated more days for egg laying at G5 and GIO.The highest values of gross reproductive rate(GRR),net reproductive rate(7.),intrinsic rate of increase(r),finite rate of increase(λ)and mean generation time(T)were found in G5 and GIO,which also showed significantly higher cq.No significant difference in the finite parasitism rate(co)was found among generations up to G15.These results suggest that T.brassicae wasps held under continuous laboratory rearing can be used successfully in biological control programs until the 15th generation without any loss of quality or performance.However,laboratory mass rearing colonies declined in quality after 15 generations and we suggest that they should be rejuvenated regularly by adding field-collected parasitoids periodically.展开更多
The majority o f adult parasitoid wasps are unable to synthesize lipids and therefore face a trade-off between the investment of lipids in eggs or in the maintenance of soma.It has been shown that resource allocation ...The majority o f adult parasitoid wasps are unable to synthesize lipids and therefore face a trade-off between the investment of lipids in eggs or in the maintenance of soma.It has been shown that resource allocation should depend on body size in parasitoids.Given that smaller females have shorter expected life times,they should concentrate their reproductive effort into early life.To test this prediction,we investigated the relationship between body size and the timing of egg production in parasitoids.We measured body size,lipid reserves,and reproductive investment(number of eggs,ovigeny index equivalent[OIE]and egg size)at eclosion in five species of Asobara(Hymenoptera:Braconidae)originating from different geographic and climatic environments.Our results show significant interspecific variation in all these traits.A diagnostic test for phylogenetic independence revealed that closely related species did not resemble each other more closely than expected by chance for all traits measured.Lipid reserves scaled positively with body size both between and within species.In agreement with theory,01 correlated negatively with body size both between and within species.Total egg area at eclosion correlated negatively with lipid reserves both between and within species.This indicates the existence of a trade-off between allocation of lipids to current reproduction and survival/future reproduction.With the exception of the most extreme pro-ovigenic species,A.pers im ilis,we found that proovigeny was compensated for by small egg size.Our results indicate the role of habitats in shaping interspecific variation in resource allocation strategies.展开更多
文摘Trichogramma brassicae(Bezdenko)is an important biological control agent that has been used widely against many lepidopteran pests.Commonly,colonies of Trichogramma are mass reared on factitious hosts such as Sitotroga cerealella(Olivier)over many generations.In this study,we evaluated the quality and performance of a colony of T.brassicae that had been reared for over 45 generations(G)using two-sex life table parameters and parasitism capacity.We found that female adult longevity was significantly different among sequential generations,ranging from 5.58±2.5 d(at G5)to 3.75±1.42 d(at G45).However,no significant difference was found in male adult longevity among different generations.Although female wasps survived longer until the 15th gener・ation,they allocated more days for egg laying at G5 and GIO.The highest values of gross reproductive rate(GRR),net reproductive rate(7.),intrinsic rate of increase(r),finite rate of increase(λ)and mean generation time(T)were found in G5 and GIO,which also showed significantly higher cq.No significant difference in the finite parasitism rate(co)was found among generations up to G15.These results suggest that T.brassicae wasps held under continuous laboratory rearing can be used successfully in biological control programs until the 15th generation without any loss of quality or performance.However,laboratory mass rearing colonies declined in quality after 15 generations and we suggest that they should be rejuvenated regularly by adding field-collected parasitoids periodically.
文摘The majority o f adult parasitoid wasps are unable to synthesize lipids and therefore face a trade-off between the investment of lipids in eggs or in the maintenance of soma.It has been shown that resource allocation should depend on body size in parasitoids.Given that smaller females have shorter expected life times,they should concentrate their reproductive effort into early life.To test this prediction,we investigated the relationship between body size and the timing of egg production in parasitoids.We measured body size,lipid reserves,and reproductive investment(number of eggs,ovigeny index equivalent[OIE]and egg size)at eclosion in five species of Asobara(Hymenoptera:Braconidae)originating from different geographic and climatic environments.Our results show significant interspecific variation in all these traits.A diagnostic test for phylogenetic independence revealed that closely related species did not resemble each other more closely than expected by chance for all traits measured.Lipid reserves scaled positively with body size both between and within species.In agreement with theory,01 correlated negatively with body size both between and within species.Total egg area at eclosion correlated negatively with lipid reserves both between and within species.This indicates the existence of a trade-off between allocation of lipids to current reproduction and survival/future reproduction.With the exception of the most extreme pro-ovigenic species,A.pers im ilis,we found that proovigeny was compensated for by small egg size.Our results indicate the role of habitats in shaping interspecific variation in resource allocation strategies.
