Safety Evaluation Of Three Agrochemicals Including Quizalofop-p-ethyl Against Propylea Japonica

Propylea japonica is an important predatory natural enemy in farmland ecosystem.For a long time,the prevention and control of farmland diseases,pests and weeds mainly rely on chemical pesticides.Although the frequent use of pesticides can control the harm of diseases and insect pests,it can also pose a threat to the population of farmland natural enemies.At present,most of the studies on the safety assessment of agricultural chemicals to natural enemies insect often take insecticide as the research object,but the types of agricultural chemicals actually used in the field are not only that.Pesticides such as herbicides,fungicides,plant growth regulators,etc.,their potential threats to natural enemy insects are unclear.In this paper,experimental zoology,RT-q PCR,16 S r RNA and transcriptome sequencing techniques were used to systematically study the changes of the growth and development,symbiotic bacteria diversity and transcriptome of P.japonica.The effects of three pesticides on the safety of P.japonica were determined.This study provides a certain theoretical support for the rational application of chemical pesticides in cotton fields,and also has practical significance for the protection of natural enemy resources in farmland.The main results of this study are as follows:1.Revealed the effects of stress of three pesticides on the biological parameters of P.japonica.Compared with the control group,the survival rate of F2 generation females(P= 0.027),F3 generation females(P = 0.023)and males(P = 0.031)of P.japonica treated with quizalofop-p-ethyl significantly increased,and reached a significant level;The body weight of males of F3 generation P.japonica increased significantly by 20.0%;There was no significant effect on longevity,pre-oviposition period and fecundity of F1,F2 and F3 generations,and there was no significant effect on larvae development period and emergence rate of F2 and F3 generations;Thiophanate-methyl and mepiquat chloride had no significant effect on body weight,survival rate,longevity,pre-oviposition period and fecundity of F1,F2 and F3 generations of P.japonica;It had no significant effect on the larval stage time(F2,F3 and F4 generations)and emergence rate(F2 and F3 generations)of P.japonica.2.The effects of three pesticide on the composition and diversity of adult bacteria of P.japonica in F3 generation were determined.The results of 16 S r RNA sequencing of the F3 generation P.japonica found that the dominant genus of adult symbiotic bacteria was Serratia;The treatment of quizalofop-p-ethyl,thiophanate-methyl and mepiquat chloride had no significant effect on the OTU numbers,richness,diversity and dominant genus composition of P.japonica symbiotic bacterial;But the contents of Wolbachia,Ralstonia,Pseudomonas,Dyella and Reyranella were significantly increased under the exposure of quizalofop-p-ethyl by 132,4.2,4.5,6.2 and 7.9 times,respectively.3.The effects of three pesticides on the transcript levels of the whole genome of F3 adults of P.japonica were clarified.By sequencing the transcriptome of F3 generation P.japonica,the differentially expressed genes under thiophanate-methyl and mepiquat chloride accounted for 0.55% and 0.10% of the total genes,respectively,and the differentially expressed genes were not significantly enriched in the KEGG pathway.After quizalofop-p-ethyl treatment,the ratio of differentially expressed genes to the total number of genes was 1.0%,and the expression levels of genes related to drug metabolism pathways such as glucuronyl transferase and glutathione S-transferase were down-regulated,mostly related differential genes in FOXO,PI3K-Akt and mTOR pathway.