| There are many researches on the causes of insecticide resistance,but few of them took gut microbiota into consideration related to the gut microbiota of insect,Meanwhile,the function of the insect gut microbiota has also been extensively studied.The purpose of this study was to reveal the relationship between the insecticide resistance of E.obliqua and the gut bacteria.The main results are listed as follows:1.Effects of different antibiotic concentrations on survival rate of E.obliqua larva and gut bacterial clearance.In this part of the experiment,200 ?g / m L,300 ?g / m L,and 400 ?g / m L antibiotics were mixed into the tea powder feed,and the survival rates between every two treatments were compared.Antibiotic clearance effect and the effect of antibiotics on the life history of E.obliqua.The results showed that the survival rate of E.obliqua fed with antibiotics at a concentration of 400?g / m L was extremely low,and E.obliqua could not complete its life history.Agarose gel result of PCR run showed that the concentration of 300?g / m L can effectively remove the gut microbiota,but the antibiotic tea powder feed at a concentration of 200?g / m L increased the total amount of gut microbes of number of gut microflora of E.obliqua,Both cultivation-based method and q PCR results confirmed that antibiotics at a concentration of 300?g / m L can effectively clear the gut microflora of E.obliqua.2.The study on gut microbiota of E.obliqua mediated insecticide resistance.we divided E.obliqua into two lines,one strain was constantly fed with bifenthrin insecticide,and the other lines was raised normally.Two lines were subcultured for fourteen generations to form resistant and sensitive lines.The semi-lethal concentration of the resistant line increased from 20.924 ?g/m L to 47.427 ?g/m L using the drip method,while the sensitive line reduced to 13.997 ?g/m L The gastrotoxicity test for the fourteenth generation found that the semi-lethal dose of the resistant strain was 68.775 ?g/m L,while the susceptible line was 33.385 ?g/m L,which was 2.06 times folds than.After antibiotic treatment,the half lethal dose of the sensitive line remained almost unchanged,but the half lethal dose of the resistant line was significantly reduced to 48.220 ?g/m L.In the experiment of in vitro degradation,we used bifenthrin as the only carbon source,cultured the gut bacterial liquid of the resistant and sensitive line,and only obtained Brevibacterium epidermidis in resistant line.The degradation rate of bifenthrin at a concentration of 5 mg per liter reached 43.98%..3.Effects of Bifenthrin treatment on the gut bacteria of E.obliqua larvae.The effect of bifenthrin on the gut microflora of the E.obliqua was compared.The results showed that the sequencing technique was used to analyze the intestinal flora structure of E.obliqua.The dominant strains of sensitive line were Firmicutes(43.91 ± 4.88%),Proteobacteria(41.88±7.83%),and Bacteroidetes(3.56±4.35%).And Cyanobacteria(9.78±7.15%),and the resistant line are Firmicutes(81.99± 0.08%),Proteobacteria(1.77±0.02%);at the level of the genus,the gut tract of inductive strains The top five bacterial abundances are Enterococcus(42.06 ± 4.17%),Wolbachia(23.84 ± 17.60%),Cyanobacteria(9.77 ± 7.16%),Acinetobacter(8.83 ± 13.62%),and Thin layer bacteria Hymenobacter(3.24 ± 4.41%),resistant strains are Enterococcus(78.82 ± 0.10%),Wolbachia(15.49±0.03%),Cyanobacteria(0.56±0.06%),Acinetobacter(0.27±0.01%),Hymenobacter(0.05±0.01%).The intestinal flora is more abundant and diverse in sensitive line than in resistant line. |
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