Studies On The Function Of Juvenile Hormone Epoxide Hydrolase And Juvenile Hormone Esterase On Diapause Ladybug,Coccinella Septempunctata L.

The ladybug Coccinella septempunctata L.is an excellent natural enemy insect,which plays an important role in the biological control of aphids.The ladybug diapause overwinters or summers in adult form.Through the regulation and control of diapause,the large-scale propagation of ladybug can be promoted and the shelf life of commercial goods can be prolonged.Juvenile hormone(JH)is an important diapause hormone,which promotes the development of insect reproductive system and vitellogenin synthesis,and regulates insect diapause.Juvenile hormone epoxide hydrolase(JHEH)and juvenile hormone esterase(JHE)are the key degrading enzymes of JH,which can regulate the level of JH in insects.In the previous study,the full length of Csjhe gene was obtained,from the data analysis of seven-star ladybug transcript group,it was found that the expression of JHEH and JHE were differentially expressed in diapause and nondiapause individuals.It is speculated that the above two enzymes play an important role in the regulation of diapause,but their function and regulatory mechanism in diapause are not clear.In this study,ladybug C.septempunctata was taken as the experimental object.The full length of Csjheh gene was cloned and the expression patterns of Csjheh and Csjhe genes in different diapause stages of ladybug were analyzed,the functions of JHEH and JHE in diapause of ladybug were studied by RNAi technique.The results are as follows:1.After diapause induction,the ovary development of ladybug was more mature than that of the control group,the content of vitellogenin increased significantly,the total lipid content remained stable,and there was no obvious lipid enrichment in the control group.Under normal conditions,the amount of oviposition increased and the pre-oviposition period shortened.2.Based on the transcriptome data of C.septempunctata,the Csjheh gene of Coccinella septempunctata was cloned by RT-PCR and RACE using diapause cDNA of 60 days as template.The full length sequence is 2077 bp,which consists of a 1380 bp open reading frame(ORF)encoding 459 amino acids residues with a molecular mass of 51.39 kda and a theoretical isoelectric point of 8.79.The results of amino acid sequence alignment showed that CsJHEH was homologous to Dendroctonus ponderosae,Tribolium castaneum,Nasonia vitripennis and Zootermopsis nevadensis,amino acid identity among them were 64.24%.3.The expression of Csjheh and Csjhe genes was detected by qPCR in each stage of diapause,normal development stage and diapause release stage of ladybug,but the expression level was significantly higher in the early emergence and diapause stage than in other stages.4.The expression of target gene was the lowest on the 7th day by RNAi technique.after interference,the content of vitellogenin increased,the content of total lipid decreased,the amount of oviposition increased,and the pre-oviposition period shortened.