Effect Of Matrine On Control Effect And Intestinal Bacterial Of Dioryctria Abietella

Dioryctria abietella is one of the main cone pests harmful to Pinus koraiensis in Northeast China.The larval stage of this pest hides in the cone to feed and develop,which seriously threatens the yield of Korean pine cone seeds.The tall pine trees increase the difficulty of prevention and control.The extensive use of pesticides in recent years has led to increased resistance of this pest.Insect gut bacteria have a profound impact on various physiological characteristics such as host development,nutrient metabolism,and foraging behavior,and also play a huge role in the production of host insect resistance.In this study,the effects of matrine on the activities of detoxification enzymes and protective enzymes in the larvae of D.abietella were determined by field experiments;Amplificon sequencing was used to study the differences in intestinal bacterial community structure of D.abietella,and to explore the effects of plant-derived pesticide matrine on the intestinal bacterial community of D.abietella,in order to reveal the role of intestinal bacteria in the host ’s resistance to pesticide stress.The main results are as follows:(1)Different concentrations of matrine had a certain effect on the control of D.abietella larvae.In the forest,500 times,1000 times,1500 times,2000 times and 2500 times liquid concentration of matrine were tested.The results showed that 5 concentrations of 2 % matrine aqueous solution could kill the larvae of D.abietella in different degrees,and the mortality rate of larvae was positively correlated with the concentration of matrine.After 2 days and 7 days of application,the mortality of larvae treated with matrine 500 times solution was the highest,47.36 % and 43.75 %,respectively.(2)Different concentrations of matrine treatment had different degrees of interference on the detoxification enzymes of D.abietella larvae.The response of detoxification enzymes to matrine was affected by treatment time and concentration.After 2 days of pesticide spraying,matrine 500 times,1000 times and 2000 times could significantly activate the detoxification enzymes of D.abietella larvae.The 1500-fold solution had an activation effect on the MFO activity of the fir shoot borer,but the effect was not significant;the Car E activity was inhibited by 2500 times liquid,and the inhibition effect was not significant.There was no significant activation and inhibition of GST and MFO activity.After 7 days of pesticide spraying,matrine at five concentrations could activate the detoxification enzymes of D.abietella larvae to varying degrees.1000 times liquid,1500 times liquid,2000 times liquid showed significant activation effect on the three detoxification enzymes;the activity of MFO was activated by 500 times and 2500 times,but the effect was not significant.(3)Matrine treatment also had different degrees of interference on the protective enzymes of the larvae of D.abietella.Similar to detoxification enzymes,the response of protective enzymes to matrine was also affected by treatment time and concentration.Two days after spraying pesticides,matrine 500 times significantly activated three protective enzyme activities(SOD,POD and PO);matrine activated POD activity first and then inhibited it.SOD activity was significantly activated by 500 times,1000 times and 2000 times.PO activity was significantly activated by 500 times,1000 times,1500 times and 2000 times.(4)Matrine affects the intestinal bacterial community composition of D.abietella larvaeThe composition and relative abundance of intestinal bacteria in D.abietella were analyzed by 16 s rDNA sequencing.The results showed that the dominant bacteria in the intestinal tract of D.abietella were Proteobacteria and Firmicutes.Compared with the control group,the abundance of Proteobacteria in the treatment group increased and the abundance of Firmicutes decreased.Matrine treatment increased the abundance of Wolbachia and Enterococcus in the larval intestine,but the increase of Wolbachia abundance was not obvious at low concentration.Rahnella1 and Pantoea are two unique genera of intestinal bacteria in the four matrine treatment groups.From the above results,it can be seen that the plant-derived pesticide matrine has a certain control effect by interfering with the detoxification enzyme and protective enzyme activities of D.abietella and its intestinal microbial community,which provides a theoretical reference for finding plant-derived pesticides that can effectively control D.abietella.