Research On The Symbiotic Bacteria SY5 Affecting On Intestinal,Olfactory Behavior And Respiratory Metabolism Of Plutella Xylostella

Plutella xylostella?L.?,one of the most serious pests of cruciferous vegetables,It is also one of the fastest pests in drug resistance development.The development of new biological insecticides to control P.xylostella and delay the development of its resistance has become our current urgent need to be solved.The entomopathogenic nematode symbiotic bacterium SY5 is a highly virulent strain screened by our research group.The toxins showed significant insecticidal activity in the indoor and outdoor against P.xylostella tests.Is an ideal biocontrol agent against the P.xylostella.In this study,16S rDNA gene sequencing technology was used to analyze the microbial diversity of the midgut V3-V4 in the healthy P.xylostella and the larvae which were feed by SY5 insecticidal toxin.The target receptor genes of SY5 toxin were screened by RT-PCR and qRT-PCR techniques.The olfactory behavior and respiratory metabolism affected by SY5 were determined.The research will provide basis for revealing the insecticidal molecular mechanism of symbiotic bacteria SY5 and a theoretical basis for the development and utilization of SY5.It is of great significance for biological control and resistance control of P.xylostella.The main findings are as follows:1.The V3-V4 regions of 16S rDNA in the midgut of P.xylostella were amplification according to the Miseq platform.And the microbial diversity information was analyzed.The results showed that compared with the midgut microbiota of the healthy P.xylostella,the community structure and bacterial richness and diversity of the midgut of the P.xylostella after feeding the symbiotic SY5 toxin significantly changed.The study showed that Pseudomonas,Geobacillus,Enterobacter,Streptococcus,Leuconostoc and Acinetobacter levels increased after the symbiotic bacteria SY5 toxin was fed.The Enterobacter bacterium increased most significantly.2.Three target acceptor genes?PxCR10-11 gene,E-P.xy-cad I and E-P.xy-cad III?of SY5 insecticidal toxins in the P.xylostella midgut were screened by RT-PCR.The expression pattern of PxCR10-11 gene between the healthy and fed SY5 toxin of P.xylostella was determined by qRT-PCR.The study found that the expression level of the gene in the healthy midgut was 2.5 times that of the fed one,and there was a significant difference between them?P<0.05?.The cadherin PxCR_10-11 gene is considered to be the receptor gene of SY5 insecticidal toxin in P.xylostella midgut preliminarily.3.The effects of symbiotic bacteria SY5 fermentation broth and insecticidal toxins on the olfactory behavior of P.xylostella were investigated using an insect olfactory analyzer.The results showed that P.xylostella had no circumvention behavior against symbiotic SY5 fermentation broth and insecticidal toxins.The effects of symbiotic bacteria SY5 fermentation broth and insecticidal toxins on the respiratory metabolism were measured using an animal insect respiration tester.The study found that the respiration rate reduced and respiratory rhythm disordered after P.xylostella ate the SY5 fermentation broth or insecticidal toxins.