Aphids suck plant juices with their sharp mouthparts,causing deterioration of plant nutrition,even defoliating,wilting and dying.In the meanwhile,aphids also spread a variety of plant viruses,which brings out severe economic losses.As aphids can live on multiple sorts of crops,they are regarded as one of most destructive pests in the agriculture.As is known to all,steroidal and oxadiazole compounds are two kind of chemical substances with good biological activity,and they are excellent activity against aphids.In this study,a series of novel core steroidal structure of perplocoside derivatives with a substituted1,3,4-oxadiazole structure were designed and synthesized,and these compounds showing remarkable bioactivities.And then,all compounds were tested their biological activities in six insects,including Schizaphis graminum,Aphis gossypii,Myzus persicae,Eriosoma lanigerum(Hausmann),Aphis citricola,and Trialeurodes vaporariorum Westwood.Based on previous researches,we also carried out a field trial to test the bioactivity of compound 20g against E.lanigerum.Forthermore,we also preliminarily explored the potential action site of compound through transmission electron microscopy(TEM).The results are as follows:Twenty-six new steroidal oxadiazole compounds were synthesized and their structures were determined by nuclear magnetic resonance,single crystal X-ray diffraction and high resolution mass spectrometry.The LC50of seven compounds against E.lanigerum,M.persicae and A.citricola were all under 100μg/ml.Notably,compound 20g exhibited excellent insecticidal activity,whose LC50 is 27.58,33.60 and 31.04μg/m L,respectively.Therefore,we drew a conclusion that compound 20g showed similar bioactivity with the positive control Chlorpyrifos(LC50=29.35μg/m L)and Thiamethoxam(LC50=28.96μg/m L).The field trial showed that the effect of compound 20g against E.lanigerum is 83.21%and 87.79%in 100 and 200μg/m L after 14th,which was similar with 40%Chlorpyrifos EC(91.31%)in 200μg/m L and 25%Thiamethoxam WG(84.15%)in 100μg/m L.And the effect of compound 20g against E.lanigerum midgut cells by transmission electron microscopy.Therefore,it can be used to become a novel alternative pesticide for field control of E.lanigerum on account of its outstanding application prospect.The LC50 of compound 23g was 151.20μg/m L,showing alike bioactivity to the positive control Spirotetramat.A series of steroidal oxadiazole derivatives were synthesized,and found that they had remarkable bioactivity against aphids,which were similar activity compared with Chlorpyrifos and Thiamethoxam.It provides relevant data support for solving the pesticide resistance crisis and insecticide research and development. |