Effects Of Host Plants And Sublethal Effects Of Cyhalothrin On The Development, Reproduction And Digestive Enzyme Activity In Lygus Pratensis

Lygus pratensis(Linnaeus)is an important pest in northwestern China,mainly damaging cash crops such as cotton and alfalfa.In this paper,we studied the effects of host plants on the development,reproduction,and digestive enzyme activity of L pratensis.The effects of sublethal of cyhalothrin on L.pratensis were also studied,and the screening of reference genes for qPCR on L pratensis was performed.The main results are as follows:1.To clarify the effects of host plant switching,the effects of eight host plants(Vigna radiata,Vigna umbellate,Glycine maxean,Glycine max,Gossypium hirsutum.,Phaseolus vulgaris,Medicago sativa and Zea mays)on the development,reproduction,survival rate of L pratensis were investigated in the lab,and amylase and trehalase activities in L.pratensis adults were determined.The results showed that different host plants had different effects on the growth and development of adults and nymphs of L.pratensis.alfalfa and green beans had a high fitness for L.pratensis.The use of green beans to raise L.pratensis promoted its growth and development.Amylase activities increased significantly after L.pratensis were switched to cotton and alfalfa,but trehalase activities were not obviously changed.2.To study the sublethal effects of cyhalothrin on the experimental population of L.Pratensis.After L.pratensis were treated with LCs and LC25 of cyhalothrin,the development duration and fertility were tested.The results showed that the treatment with LC5 and LC25 cyhalothrin shortened the adult lifespan,pre-ovulation period and spawning period,and decreased single-female egg production.Moreover,the F1 generation nymph developmental duration was slightly extended,and survival rate was significantly reduced.3.The mRNA expression stability of ten house-keeping genes(a-tubulin,β-tubulin,ACT,EF,SDHA,UBQ,TAF,GST,RPL32,and TATA-box)was detected by the quantitative real-time PCR(qPCR).The results showed that the analysis by BestKeeper,NormFinder,geNorm and RefFinder showed that the optimal internal reference genes for different adult parts were RPL32,TAF,RPL32 and RPL32,respectively.The optimal internal reference genes for different resistant adults were RPL32,GST,EF,RPL32 and RPL32,respectively.The optimal internal reference genes for different temperature treatments was UBQ.The optimal internal reference genes for different sex adults were TAF,SDHA,SDHA and SDHA,respectively.The optimal internal reference genes for different insecticide treatments were RPL32,EF,β-tubulin and β-tubulin,respectively.The optimal internal reference genes for different developmental stages were ACT,UBQ,TAF and TAF,respectively.In these six groups,it showed that the best combination of reference genes was RPL32+ TAF,RPL32+GST,UBQ+ACT+β-tubulin,SDHA+GST,β-tubulin+TAF+RPL32 and TAF+ GST+UBQ,respectively.