The Physiological And Biochemical Mechanisms Of Resurgence Of Brown Planthoppers(Nilaparvata Lugens St(?)l) Induced By Insecticides And Effects Of Insecticides On Enzyme Activity Of Non-target Species

Brown planthopper(BPH) Nilaparvata lugens(St(?)l) is an important insect pest of rice in China,often outbreaks in some areas which resulted in serious damage of serious rice production.In particular,BPH resurgence occurred in recent years,which led to serious threat to rice production.The examination of BPH resurgence mechanism was important significance for sustainable insect control.In this paper,we researched the effects of insecticides and the rice variety on levels of crude fat and soluble sugars in brown planthopper under insecticide-induced reproduction stimulation,and effects of insecticides on enzyme activity of BPH and other non-target species.The results are as follows:1.Effects of insecticides and the rice variety on levels of crude fat and soluble sugars in brown planthopper,Nilaparvata lugens(St(?)l)(Homoptera: Delphacidae) under insecticide-induced reproduction stimulationThe percentage of brachypterous adults and number of laid egg by femal adults developed from nymphs feeding on the plants treated with insecticides varied significantly with rice varieties,insecticide varieties and their consentrations.The number of laid eggs by femal adults developed from nymphs fed on treated TN1 plants was significantly higher than that on Xieyou 963.The number on plants treated with triazophos was significantly higher than that with deltamethrin and imidacloprid.The number on plants treated with high concentrations of the insecticides was significantly higher than that with middle and low concentrations and on control(untreated) plants,increasing 9.9%,108.5% and 205%,respectively.Contents of crude fat and soluble sugar in the insect that developed from feeding on plants treated with insecticides significantly varied with rice varieties insecticides and their concentrations.Three-way Anova showed that crude fat and soluble sugar contents in fifith instar numph and adult on treated TN1 plant were significantly highter than those on treated Xieyou 963 plant except for third instar numph.Content of crude fat and soluble sugar in adult developed from TN1 and in third and fifth instar nymphs and adult from Xieyou 963 significantly increased compared to control.2.The activity of enzyme in BPH and other non-target species under stress of several insecticidesThe present paper examined physiological and biochemical changes in BPH and several non-target species in rice field following insecticide treatments.The results showed that there was no significant changes in catalase and superoxide dismutase activity in BPH following insecticide treatments,however,there was a significant increase of carboxylesterase and glutathione-S-transfer activity.In contrast,the enzyme activity of uperoxide dismutase and POD in rice leaffolder and wolf spider significantly decreased,but there was no impact of insecticides on carboxylesterase and GST.Arginine contents in BPH following insecticides treatments was relected to rice variety,insecticide varieties and their concentrations and that for insecticide treatments was significantly higher than that for control.