The Functional Study Of Key Genes For Insulin Signaling Pathway In Imidacloprid Induced Stimulation Of Reproduction In Cyrtorhinus Lividipennis Reuter(Hemiptera:Miridae)

The mirid bug,Cyrtorhinus lividipennis(Reuter)(Hemiptera:Miridae),preys on the eggs and nymphs of brown planthopper(Nilaparvata lugens)and plays an important role in the integrated management of rice pests.In agricultural system,chemical control is a commonly used management tactic against rice pests,which may produce sublethal effects on C.lividipennis.Our previous studies indicated that the sublethal concentrations of imidacloprid increased the fecundity of C.lividipennis,and this phenomenon may be mediated by insulin signaling pathway.In this study,the function of serine/threonine kinase(ClAkt)in the imidacloprid-induced reproduction of C.lividipennis was studied.The mainly results were as follows:(1)The sequences and the spatio-temporal expression profiles of ClAkt and ClPI3K1 in C.lividipennis.The full-length sequences of ClAkt(Genbank ID:MT096376)and ClPI3K1(Genbank ID:MT096375)were 2,969 bp and 3,614 bp,respectively.The qPCR results showed that ClAkt and ClPI3K1 were primarily expressed during the adult stages,and the expression of these two genes continued increasing to reach the peak on day 5.The ClAkt had highest expression level in the midgut of 5th-instar nymph and newly emerged female adults of(about 27-fold and 41-fold higher than that in the thorax,respectively).The ClPI3K1 had highest expression level in the midgut of 5th-instar nymph and newly emerged female adults of(about 18.8-fold and 25.59-fold higher than that in the thorax,respectively).(2)The function of ClAkt in reproduction and its function in imidacloprid-induced reproduction of C.lividipennis.The qPCR was employed to investigate the expression of ClAkt in C.lividipennis treated with a sublethal concentration of imidacloprid.The expression level of ClAkt was increased by 330.57%,202.59%,26.58%at 1 d,2 d and 3 d after treated,respectively.The expression of ClAkt in midgut of C.lividipennis which was treated with a sublethal concentration of imidacloprid for 1 d was increased by 70.65%.These results indicated that imidacloprid stimulated the expression of ClAkt in C.lividipennis female adults.RNA interference-mediated knockdown of ClAkt significantly reduced the transcription of ClVg by 57.77%,and the numbers of eggs laid by dsAKT injected C.lividipennis were reduced 48.51%.The expression of ClVg in C.lividipennis treated with imidacloprid was increased by 154.18%,and the numbers of eggs laid by imidacloprid treated C.lividipennis was increased by 49.58%.Furthermore,the expression of ClVg in dsAKT+imidacloprid treated C.lividipennis was increased by 104.90%,and the numbers of eggs laid by dsAKT+imidacloprid treated C.lividipennis was increased by 20.57%.These results indicated that ClAkt plays roles in reproduction of C.lividipennis,and the imidacloprid-induced reproduction of C.lividipennis might result from the up-regulation of ClAkt.