Effects Of Different Conditions Stresses On Diversity Of Intestinal Microbes Of Grapholitha Molesta And Cydia Pomonella

Grapholitha molesta and Cydia pomonella are two important insect on drupe and pome fruit trees.It is mainly through eating new shoots and drilling into the fruit to eat the fruit damage,which causes significant loss of fruit quality and yield.In the long-term evolution process,insects and gut microbes select and adapt to each other,forming a very close relationship.Intestinal microorganisms can not only provide nutrients necessary for insect growth and development,but also produce a large number of enzymes to help the host digest food,and at the same time detoxify the host,defend against natural enemies,resist pathogen invasion.At present,most domestic researches on the Grapholitha molesta and Cydia pomonella focus on biology,ecology,integrated pest management,etc.The research on the intestinal microbial diversity of the two insects has not been reported.Based on the complex functions of intestinal microbes,we continue to in-depth study their drug resistance.In this study,16S r RNA technology was used to analyze the intestinal microbial composition of Grapholitha molesta and Cydia pomonella in different environmental conditions such as chemical agents,Beauveria bassiana and antibiotics.It aims to provide theoretical data reference for target control and drug resistance research.The main findings are as follows:1.The effects of the lethal concentration of four insecticides on the intestinal microbial diversity of Grapholitha molesta and Cydia pomonella.Grapholitha molesta and Cydia pomonella were most sensitive to Tetrachlorantraniliprole,with LC₅₀ values of 5.752 mg/L and 6.883 mg/L,Chlorantraniliprole was the least toxic to the larvae of Grapholitha molesta and Cydia pomonella among the four insectcide,with LC₅₀values of 53.975 mg/L and 63.434 mg/L,so Tetrachlorantraniliprole was chosen to control the Grapholitha molesta and Cydia pomonella.The diversity,richness and uniformity of the intestinal bacteria gruop are significantly reduced.Proteobacteria is the dominant bacteria phyla in all samples of Grapholitha molesta and Cydia pomonella treated with four insecticides.The relative abundance of the Proteobacteria in each treatment group of Grapholitha molesta is greater than the Cydia pomonella.Moraxellaceae is the dominant bacteria family of the four insecticides treatment group of Grapholitha molesta,the secondary dominant bacteria family is Enterobacteriaceae,Enterobacteriaceae is the dominant bacteria family of control group of Grapholitha molesta and Cydia pomonella treated with four insecticides,the secondary dominant bacteria family is Moraxellaceae.The dominant family of the Cydia pomonella control group is Enterobacteriaceae,and the secondary dominant family is Yersiniaceae.The relative abundance of Yersinaceae in the intestines of two kinds of fruit borers was significantly different,1.0%and 23.8%,respectively.The relative abundance of Enterobacteriaceae of the four insecticides in the lethal concentration to treat Grapholitha molesta was significantly lower than that of the Cydia pomonella.The dominant genus of all samples was Acinetobacter.The relative abundance of Serratia in the Grapholitha molesta control group was significantly greater than the Cydia pomonella control group.The relative abundance of Acinetobacter in Cydia pomonella treated with four insecticides was significantly greater than that of the same insecticide-treated Grapholitha molesta.The content of Grapholitha molesta treated with Tetrachlorantraniliprole was the lowest among all samples,the value is 8%,while the Grapholitha molesta and the Cydia pomonella were the most sensitive to Tetrachlorantraniliprole,and the Grapholitha molesta.is more sensitive to it than the Cydia pomonella The reason is related to the detoxification and immune regulation,digestion and metabolism.of Acinetobacter and Serratia.2.The effects of Beauveria bassiana on the intestinal microbes of Grapholitha molesta and Cydia pomonella.Different concentrations of Beauveria bassiana infested Grapholitha molesta and Cydia pomonella,both pests weakened their activities,slowed their movement speed,gradually swelled their bodies,gradually turned yellow-brown in color,bent their bodies,and completely curled up dead.Continue to cultivate the insect body to grow white hyphae,and then the insect body is covered with white conidia.When the concentration is greater than1.5×10³ spores/m L,it has a significant inhibitory effect on the changes in body weight and body length of Grapholitha molesta and Cydia pomonella（P<0.05）,and both increase with time,which will affect the body weight and body length of the two pests.The effect of inhibiting changes is more obvious（P<0.05）.1.5x10⁷ spores/m L and1.5x10⁵spores/m L can be selected as the most economical and effective concentration to control Grapholitha molestas;and Cydia pomonella.The diversity,dominance and abundance of the intestinal bacteria group of the two insects were lower than those of the control,with the increase of the concentration of Beauveria bassiana,the more obvious the effect on the intestinal bacteria group of Grapholitha molesta and Cydia pomonella.Proteobacteria is the dominant phylum among all samples infected with different concentrations of Beauveria bassiana for Grapholitha molesta and Cydia pomonella.The relative abundances of Proteobacteria and Firmicutes of Grapholitha molesta and Cydia pomonella in different concentrations Beauveria bassiana treatment groups were increased compared with the control.The dominant genus of high-concentration Beauveria bassiana infected Grapholitha molesta is Serratia,which accounts for 24.51%,and others treaement group dominant genus of each treatment is Acinetobacter.The difference of bacterial genus of High-concentration of Beauveria bassiana infecting Grapholitha molesta and Cydia pomonella were Serratia.The relative abundance of Acinetobacter in the intestine of Cydia pomonella infected with low,medium and high concentrations of Beauveria bassiana was greater than that of the same concentration treatment of Grapholitha molesta.Serratia and Acinetobacter can detoxify,digest and decompose cellulose.Therefore,different concentrations of Beauveria bassiana infects Grapholitha molesta and Cydia pomonella to change the type and abundance of intestinal bacteria,which also affects its growth and development.3.The effects of changes in intestinal microbes of Grapholitha molesta and Cydia pomonella on their nutritional metabolism.Antibiotic treatment reduced the dominance,richness and diversity of intestinal bacterial group of Grapholitha molesta and Cydia pomonella,and the diversity and richness of intestinal samples of Cydia pomonella treated with antibiotics were higher than that of Grapholitha molesta.Proteobacteria are the dominant bacteria in all samples of Grapholitha molesta and Cydia pomonella treated with antibiotics.The dominant bacterial order of the Cydia pomonella control group was Enterobacter,Pseudomonadales is the dominant order of the Cydia pomonella antibiotic treatment group,the Grapholitha molesta antibiotic treatment group and the control group.The dominant order of the Cydia pomonella control group is Enterobacteriaceae,The relative abundances of Enterobacter and Pseudomonas in the antibiotic treatment group of Cydia pomonella were higher than those in the treatment group of Grapholitha molesta.Acinetobacter was the dominant genus of all samples.The relative abundances of Acinetobacter in the antibiotic treatment group of Grapholitha molesta and Cydia pomonella increased by 31.5%and 36.2%than each control group,The relative abundance of Serratia was reduced compared with the control by 0.9%and 23.1%.Antibiotic treatment of Grapholitha molesta and Cydia pomonella reduced the relative abundance of Massilia by 0.1%and 0.7%With the increase of treatment time,the antibiotic treatment of Grapholitha molesta had no significant effect on body length,but had a significant effect on body weight.It has a significant effect on the contents of albumin,glucose and triglyceride in the body of Grapholitha molesta（P<0.05）,and has a significant effect on the content of albumin and triglyceride in the Cydia pomonella（P<0.05）and the effect on glucose content is not significant（P>0.05）.Therefore,the antibiotic treatment of Grapholitha molesta and Cydia pomonella caused significant changes in the intestinal bacterial groups,reduced the diversity of intestinal bacterial groups,and also reduced the abundance of the dominant bacteria Serratia and Marseilla,it affects the growth and nutrient changes of Grapholitha molesta and Cydia pomonella.In summary,the use of four insecticides,different concentrations of Beauveria bassiana and antibiotics to treat Grapholitha molesta and Cydia pomonella affects the diversity of intestinal bacteria and changes the abundance of intestinal bacterial groups It was found that the relative abundance of Acinetobacter,Serratia,and Massilia in the dominant genus after treatment with different environmental factors changed significantly,thereby enhancing host resistance and affecting host growth and development.Therefore,it is necessary to explore the target and mechanism of the change of the intestinal bacterial groups with Grapholitha molesta and Cydia pomonella.