Synergistic Effects Of Three Thiosemicarbazone Compounds On Chlorantraniliprole Against Plutella Xylostella

Diamondback moth?Plutella xylostella L.?is an important vegetable pest,which is resistant to 95 active ingredients because of its short life cycle,strong reproductive capacity,high dose and frequent use of pestcide in production.Chlorantraniliprole,as a kind of bisamide insecticide,has been widely recognized in the market since it was put on the market because of its new target,good quick-acting persistence and low toxicity to mammals.However,with the wide use of pesticides,the resistance of diamondback moth to chlorantraniliprole is becoming more and more prominent.In order to dissect the mechanism of phenoloxidase-mediated immune involved in the development of resistance to chlorantraniliprole in diamondback moth?Plutella xylostella?,and to identify the possibility of phenol oxidase high-efficiency inhibitor as synergistic agent to control Plutella xylostella,indoor bioassay,fluorescence quantitative PCR,western blotting,enzyme activity determination were carried out.Here are the following results:1.Based on the former resistance selection,the resistance level of diamondback moth?Plutella xylostella?to chlorantraniliprole was obtained from dropping method.The results showed that the LD₅₀ of the resistant population was 411.39 g/g and the resistance multiple was 473 times of the sensitive population.2.3,4-dihydroxybenzaldehyde thiosemicarbazone?hereinafter,compound A?,4-methoxybenzaldehyde thiosemicarbazone?compound B?,salicylaldehyde thiosemicarbazone?compound C?and other thiosemicarbazone compounds were incubated for 24 hours,and then the toxicity of the thiosemicarbazone compounds was determined by chlorantraniliprole.The results showed that the resistance of diamondback moth induced by compounds A and B increased by 37.87 and 26.09 times in different generations.The resistance multiple of diamondback moth decreased after induction of compound C,and the resistance of different generations decreased by 13.42 times on average.3.The transcriptional level of PPO,relative expression level of PPO 2 and PO unit enzyme activity were quantified by fluorescence quantitative method,western blotting and enzyme activity measurement.The results showed that the changes of phenoloxidase induced by chlorantraniliprole alone were not obvious and almost unchanged.The transcriptional level of phenoloxidase,relative expression level and unit enzyme activity of Plutella xylostella induced by compounds A and B were significantly higher,but those induced by compound C were significantly lower comparing to the control group.4.Salicylaldehyde thiosemicarbazone can be used as a synergist in combination with chlorantraniliprole to control resistant diamondback moth.