In assessing an insect-resistant genetically engineered(IRGE)crop before its commercialization,researchers normally use so-called"Tier-1 assays"as the initial step to determine the effects of the crop on non...In assessing an insect-resistant genetically engineered(IRGE)crop before its commercialization,researchers normally use so-called"Tier-1 assays"as the initial step to determine the effects of the crop on non-target organisms.In these tests,the insecticidal proteins(IPs)produced by the IRGEs are added to the diets of test organisms in the laboratory.Test organisms in such assays can be directly exposed to much higher concentrations of the test IPs than they would encounter in the field.The results of Tier-1 assays are thus more conservative than those generated in studies in which the organisms are exposed to the IPs by feeding on IRGE plant tissue or in the case of predators or parasites,by feeding on invertebrate prey or hosts that have fed on IRGE plant tissue.In this report,we consider three important factors that must be considered in Tier-1 assays:(i)methods for delivery of the IP to the test organisms;(ii)the need for and selection of compounds used as positive controls;and(iii)methods for monitoring the concentration,stability and bioactivity of the IP during the assay.We also analyze the existing data from Tier-1 assays regarding the toxicity of Bt Cry proteins to non-target arthropod species.The data indicate that the widely used Bt proteins have no direct toxicity to non-target organisms.展开更多
The biological parameters of Macrolophus pygmaeus Rambur afler prolonged rearing in the absence of plant materials were compared with those of conventionally plant-reared predators. When eggs of Ephestia kuehniella Ze...The biological parameters of Macrolophus pygmaeus Rambur afler prolonged rearing in the absence of plant materials were compared with those of conventionally plant-reared predators. When eggs of Ephestia kuehniella Zeller were provided as food, developmental and reproductive fitness of M. pygmaeus reared for over 30 consecutive generations using artificial living and oviposition substrates was similar to that of predators kept on tobacco leaves. Plantless-reared fifth instars of the predator also had similar predation rates on second instars of the tobacco aphid, Myzus persicae nicotianae Blackman, as their peers maintained on plant materials. In a further experiment, predation on aphid prey by fifth instar M. pygmaeus fed one of two egg yolk-based artificial diets was compared with that of nymphs fed E. kuehniella eggs. Despite their lower body weights, preda- tors produced on either artificial diet killed similar numbers of prey as their counterparts reared on lepidopteran eggs. Our study indicates that artificial rearing systems may be useful to further rationalize the production of this economically important biological control agent.展开更多
文摘In assessing an insect-resistant genetically engineered(IRGE)crop before its commercialization,researchers normally use so-called"Tier-1 assays"as the initial step to determine the effects of the crop on non-target organisms.In these tests,the insecticidal proteins(IPs)produced by the IRGEs are added to the diets of test organisms in the laboratory.Test organisms in such assays can be directly exposed to much higher concentrations of the test IPs than they would encounter in the field.The results of Tier-1 assays are thus more conservative than those generated in studies in which the organisms are exposed to the IPs by feeding on IRGE plant tissue or in the case of predators or parasites,by feeding on invertebrate prey or hosts that have fed on IRGE plant tissue.In this report,we consider three important factors that must be considered in Tier-1 assays:(i)methods for delivery of the IP to the test organisms;(ii)the need for and selection of compounds used as positive controls;and(iii)methods for monitoring the concentration,stability and bioactivity of the IP during the assay.We also analyze the existing data from Tier-1 assays regarding the toxicity of Bt Cry proteins to non-target arthropod species.The data indicate that the widely used Bt proteins have no direct toxicity to non-target organisms.
文摘The biological parameters of Macrolophus pygmaeus Rambur afler prolonged rearing in the absence of plant materials were compared with those of conventionally plant-reared predators. When eggs of Ephestia kuehniella Zeller were provided as food, developmental and reproductive fitness of M. pygmaeus reared for over 30 consecutive generations using artificial living and oviposition substrates was similar to that of predators kept on tobacco leaves. Plantless-reared fifth instars of the predator also had similar predation rates on second instars of the tobacco aphid, Myzus persicae nicotianae Blackman, as their peers maintained on plant materials. In a further experiment, predation on aphid prey by fifth instar M. pygmaeus fed one of two egg yolk-based artificial diets was compared with that of nymphs fed E. kuehniella eggs. Despite their lower body weights, preda- tors produced on either artificial diet killed similar numbers of prey as their counterparts reared on lepidopteran eggs. Our study indicates that artificial rearing systems may be useful to further rationalize the production of this economically important biological control agent.
