| Insect sex pheromones are trace information compounds that carry out chemical communication between male and female insects of the same species after sexual maturity of sexual reproduction insects,could attract the opposite sex to approach and ensure the successful completion of courtship and mating process.Plagiodera versicolora(Coleoptera:Chrysomelida)is one of the most important pests of Salicaceae,which seriously damages vegetation and causes extremely serious economic losses to the development of landscape industry.Sex pheromones,as a new technology of integrated pest management,have been widely used in pest monitoring and management at home and abroad.However,sex pheromones and their related genes of P.versicolora has not been studied.In this paper,the dynamic rhythm of courtship and mating,the isolation and identification of sex pheromones,the behavioral determination of candidate active components,and the transcriptome sequencing and analysis of gonad tissues before and after sexual maturity of P.versicolora were systematically studied.The main results are as follows:1.The P.versicolora adopt knapsack mating,with male on top and female on bottom.They only seek mating and mating in light period.Most of them could develop sexual maturity on the 3-4 days after eclosion,and the peak of mating time is 0.5 h to 2.5 h after photoperiod.The Y type olfactory selection test showed that P.versicolora sex pheromones were released by female,and the most suitable solvent for extracting sex pheromones was hexane.2.The sex pheromones of P.versicolora were extracted by organic solution soaking method,and the gonadal extracts were analyzed by gas chromatography-antennae potential(GC-EAD)and gas chromatography-mass spectrometry(GC-MS).It was found that there were 15 compounds in female same as male gonadal extracts.There were 26 and 30 specific compounds were identified from male and female gonadal extracts,respectively.According to the results of GC-EAD,three active substances were found in the gonadal extract,which could induce antennae electrical response in male adult of P.versicolora.Three candidate compounds were 2-methylnonane,salicylaldehyde and 2-(2-Butoxyethoxy)ethyl acetate.3.The standard of three compounds were selected and conducted GC-EAD antennae potential analysis,and the results showed that three compounds caused a significant antennae potential response in male adult P.versicolora.To test the behavioral responses of male adults for the sex pheromone components,a Y-tube olfactometer assay was conducted.The male adults showed significantly selected to 2-(2-Butoxyethoxy)ethyl acetate at 1,0.1,0.01 μg/μL.Therefore,2-(2-Butoxyethoxy)ethyl acetate was identified as the candidate sex pheromone component of P.versicolora.4.The transcriptome sequencing of female gonads was performed on Illumina sequencing technology and 40910 transcripts were obtained.According to the preliminary identification of P.versicolora sex pheromone components 2-(2-Butoxyethoxy)ethyl,a total of 106 genes related to sex pheromone biosynthesis were identified,including 3 ACC genes,16 FAS genes,19 FAR genes,16 ATF genes and 52 cytochrome P450 genes.The expression levels of 106 candidate genes related to sex pheromone synthesis before and after sexual maturation were analyzed,and 24 genes were significantly up-regulated,including 5 FAS genes,5 FAR genes,1 ATF gene and 13 CYP450 genes.These genes may be involved in the biosynthesis process of sex pheromone of P.versicolora.In this study,the courtship behavior and the release rhythm of sex pheromone were obtained of P.versicolora.The preliminary identification and activity verification showed2-(2-Butoxyethoxy)ethyl was the sex pheromone in P.versicolora.According to the expression of female gonadal transcripts and the structure of sex pheromone,the biosynthetic pathway was speculated and 24 genes that might be involved in the biosynthetic process of the sex pheromone were obtained.The results of this study not only provided basic data for the study of the structural components of sex pheromones and the molecular mechanism of biosynthesis,but also provided a natural and efficient method for the control of P.versicolora,which is expected to reduce the use of pesticides and improve the environmental safety of gardens. |
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