The comprehensive knowledge that the delayed systemic and reproduction side effects can be even more deleterious than acute toxicity, has caused a shift in focus toward sublethal effects assessment on physiology and b...The comprehensive knowledge that the delayed systemic and reproduction side effects can be even more deleterious than acute toxicity, has caused a shift in focus toward sublethal effects assessment on physiology and behavior of beneficial insects. In this study, we assessed the risks posed by some insecticides with different mode of action through lethal and delayed systemic sublethal effects on the pupation, adult emergence, and repro- duction of the chrysopid Chrysoperla externa （Hagen, 1861; Neuroptera： Chrysopidae）, an important predator in pest biological control. The maximum field recommended dose （MFRD） and twice （2xMFRD） for chlorantraniliprole, tebufenozide, and pyriproxyfen were harmless to C. externa. In contrast, all the tested chitin synthesis inhibitors （CSIs） were highly detrimental to the predator, despite of their lack of acute lethal toxicity. There- fore, the safety assumed by using IGRs toward beneficial insects is not valid for chrysopids. Dose-response data showed that although all CSIs have a similar mechanism of action, the relative extent of toxicity may differ （novaluron 〉 lufenuron 〉 teflubenzuron）. For CSIs, the delayed systemic effects became obvious at adult emergence, where the predicted no observable effect dose （NOED） was 1/2 048 of the MFRD for novaluron （0.085 ng/insect）, and 1/256 of the MFRD for both lufenuron （0.25 ng/insect） and teflubenzuron （0.6 ng/insect）. Finally, this work emphasized the significance of performing toxicity risk assessments with an adequate posttreatment period to avoid underestimating the toxicities of insecticides, as the acute lethal toxicity assays may not provide accurate information regarding the long-range effects of hazardous compounds.展开更多
ABC transporters have been suggested to be involved in insecticide detoxification in different insect species mainly based on the indirect observation of transcriptional upregulation of ABC gene expression in response...ABC transporters have been suggested to be involved in insecticide detoxification in different insect species mainly based on the indirect observation of transcriptional upregulation of ABC gene expression in response to insecticide exposure.Previous studies performed by us and others in the red flour beetle,Tribolium castaneum,have analyzed the function of TcABCA-C and TcABCG-H genes using RNA interference(RNAi)and demonstrated that specific TcABCA and TcABCC genes are involved in the elimination of the pyrethroid tefluthrin and the benzoylurea diflubenzuron,because gene silencing increased the beetle's susceptibility to the insecticides.In this study,we focused on the potential functions of TcABCA-C genes in detoxification of the pyrethroid cyfluthrin(CF),the organophosphate malathion(MAL)and the diacylhdyazine tebufenozide(TBF).Analysis of transcript levels of selected TcABCA-C genes in response to treatment with these three chemically unrelated insecticides revealed that some genes were particularly upregulated after insecticide treatment.In addition,the ABC inhibitor verapamil synergized significantly the toxicity of MAL but only negligibly CF and TBF toxicities.Finally,silencing of two TcABCC genes by RNAi revealed a significant increase in susceptibility to MAL.In contrast,we did not observe a significant increase in insecticide-induced mortalities when knocking down TcABC genes in larvae treated with CF or TBF,although they were upregulated in response to insecticide treatment.Our results suggest that two pleiotropic ABCC transporters expressed in metabolic and excretory tissues contribute to the elimination of MAL.展开更多
文摘The comprehensive knowledge that the delayed systemic and reproduction side effects can be even more deleterious than acute toxicity, has caused a shift in focus toward sublethal effects assessment on physiology and behavior of beneficial insects. In this study, we assessed the risks posed by some insecticides with different mode of action through lethal and delayed systemic sublethal effects on the pupation, adult emergence, and repro- duction of the chrysopid Chrysoperla externa （Hagen, 1861; Neuroptera： Chrysopidae）, an important predator in pest biological control. The maximum field recommended dose （MFRD） and twice （2xMFRD） for chlorantraniliprole, tebufenozide, and pyriproxyfen were harmless to C. externa. In contrast, all the tested chitin synthesis inhibitors （CSIs） were highly detrimental to the predator, despite of their lack of acute lethal toxicity. There- fore, the safety assumed by using IGRs toward beneficial insects is not valid for chrysopids. Dose-response data showed that although all CSIs have a similar mechanism of action, the relative extent of toxicity may differ （novaluron 〉 lufenuron 〉 teflubenzuron）. For CSIs, the delayed systemic effects became obvious at adult emergence, where the predicted no observable effect dose （NOED） was 1/2 048 of the MFRD for novaluron （0.085 ng/insect）, and 1/256 of the MFRD for both lufenuron （0.25 ng/insect） and teflubenzuron （0.6 ng/insect）. Finally, this work emphasized the significance of performing toxicity risk assessments with an adequate posttreatment period to avoid underestimating the toxicities of insecticides, as the acute lethal toxicity assays may not provide accurate information regarding the long-range effects of hazardous compounds.
基金We are grateful to Johanne Tietmeyer for generating the used pGEM-T plasmids containing TcABC-cDNA inserts.This work was supported by a grant from the Deutsche Forschungsgemeinschaft(DFG Me2210/4-1).
文摘ABC transporters have been suggested to be involved in insecticide detoxification in different insect species mainly based on the indirect observation of transcriptional upregulation of ABC gene expression in response to insecticide exposure.Previous studies performed by us and others in the red flour beetle,Tribolium castaneum,have analyzed the function of TcABCA-C and TcABCG-H genes using RNA interference(RNAi)and demonstrated that specific TcABCA and TcABCC genes are involved in the elimination of the pyrethroid tefluthrin and the benzoylurea diflubenzuron,because gene silencing increased the beetle's susceptibility to the insecticides.In this study,we focused on the potential functions of TcABCA-C genes in detoxification of the pyrethroid cyfluthrin(CF),the organophosphate malathion(MAL)and the diacylhdyazine tebufenozide(TBF).Analysis of transcript levels of selected TcABCA-C genes in response to treatment with these three chemically unrelated insecticides revealed that some genes were particularly upregulated after insecticide treatment.In addition,the ABC inhibitor verapamil synergized significantly the toxicity of MAL but only negligibly CF and TBF toxicities.Finally,silencing of two TcABCC genes by RNAi revealed a significant increase in susceptibility to MAL.In contrast,we did not observe a significant increase in insecticide-induced mortalities when knocking down TcABC genes in larvae treated with CF or TBF,although they were upregulated in response to insecticide treatment.Our results suggest that two pleiotropic ABCC transporters expressed in metabolic and excretory tissues contribute to the elimination of MAL.
