The Effects Of Continuous Elevated CO₂ On Helicoverpa Armigera And The Explore Of Function Of Bacillus Safensis AN1

Elevated atmospheric CO₂ concentration is one of the key factors of global warming,which can produce complex and far-reaching effects on the organisms in ecosystem of the earth.Three different CO₂ concentrations?control:380?l/L,intermediate-elevated:550?l/L and double-elevated:750?l/L?were set for researching the important chewing pest cotton bollworm?Helicoverpa armigera?on economic crop cotton in this study.The effects of continuous elevated CO₂ concentration on the growth and development,expression of key metabolic gene,microbial composition of H.armigera in multiple generations?more than 20 generations?,and the growth and physiological microbial function of Bacillus safensis for cotton bollworm were researched.The experiment results are as follows:1 Effects of continuous elevated CO₂ on the two sex life table of cotton bollworm.The effects of different CO₂ concentrations on growth and development parameters of the 20th generation of H.armigera were analyzed by using the two-sex life table.The results showed that significantly lower larval duration?P<0.05?and female larvae?P<0.05?and significantly higher pupal weight of female?P<0.05?were observed under 550?l/L and 750?l/L CO₂ concentrations treatments relative to 380?l/LCO₂ treatment.The survival rate of cotton bollworm was the lowest at the treatment of 550?l/L CO₂concentration.The population parameter results showed that significantly lower mean generation time T of the population by 26.563 d was found under 750?l/L CO₂ treatment than those of 380?l/LCO₂ treatment?P<0.05?.The finite consumption rate?was increased obviously in 750?l/L CO₂ treatment compared with380?l/L CO₂ treatment?P<0.05?.The results showed that significantly higher population consumption?P<0.05?,growth of population?P<0.05?and the population quantity?P<0.05?of cotton bollworm were observed in 750?l/L CO₂ treatment relative to 380?l/L CO₂ treatment.2 Effect of elevated CO₂ concentration on the expression of genes on cotton bollwormThe gene expression related to the development and stress protein were detected by real-time fluorescence quantitative RT-PCR.The results showed that the expression levels of growth and development related genes?JHE,EcR?and stress protein genes?Hsp90,Hsp70,Hsc70?of cotton bollworm were up-regulated under the 750?l/L CO₂ treatment relative to 380?l/L CO₂ treatment.The expression levels of Hsp90 and JHE were significantly up-regulated by 2.0 and 2.1 times,respectively,under 750?l/L CO₂treatment relative to 380?l/L CO₂ treatment?P<0.05?,which was increased 2.0 and 2.1times respectively to the control.Under the treatment of 550?l/L CO₂,the relative expression of genes Hsp90 and JHE of cotton bollworm were not significantly different from those in the control 380?l/L CO₂ concentration?P>0.05?.There was no significant difference in the expression levels of Hsp70 and Hsc70 among there different CO₂concentrations?P>0.05?.3 Isolation and identification of culturable bacteria from the midgut of cotton bollworm under the different CO₂ concentrationsThe results showed that 20 strains of intestinal culturable bacteria were isolated from380?l/L CO₂ treatment,10 strains of intestinal culturable bacteria were isolated at550?l/L CO₂ treatment,and 13 strains of intestinal culturable bacteria were isolated from750?l/L CO₂ treatment by traditional isolated method and 16S rRNA sequencing technology.The results showed that the bacteria isolated from 380?l/L and 550?l/L CO₂treatment were both high homology with Proteobacteria and Firmicutes,and the bacteria isolated from 750?l/L CO₂ concentrations was high homology with Firmicutes and Actinomycetes.Firmicutes were the dominant culturable bacteria of cotton bollworm intestinal tract at different CO₂ concentrations,among which Bacillus subtilis and Bacillus safensis were the most abundant and numerous species.The results showed that Bacillus safensis can form an obvious hydrolysis cycle in the screening of medium,indicating that Bacillus safensis can decompose cellulose and protein in our research.4 Effect of Bacillus safensis AN1on the nutritional and enzyme activity of cotton bollwormThe dominant strain Bacillus safensis AN1 isloted from intestinal of cotton bollworm was selected and added into the ordinary artificial diet to feed cotton bollworm,the nutritional index and metabolic enzyme activity of cotton bollworm were determined.The results showed that,the consumption,the fecal excretion and the protein content of cotton bollworm were significantly increased fed on Bacillus safensis AN1 compared with those fed on normal artificial diet?P<0.05?.After feeding on Bacillus safensis AN1,the approximate digestibility?AD?and food net conversion?ECD?of cotton bollworm were reduced significantly those fed on normal artificial diet?P<0.05?.After feeding on Bacillus safensis AN1,the activity of catalase?CAT?in cotton bollworm was significantly higher than those of fed on normal artificial diet treatment?P<0.05?,and the activity of total superoxide dismutase?T-SOD?was significantly lower than that those in fed on normal artificial diet treatment?P<0.05?.There were no significant differences in the content of trehalose,the total antioxidant capacity?T-AOC?,the relative growth rate?RGR?,the relative consumption rate?RCR?,the mean relative growth rate?MRGR?,and the efficiency of conversion of ingested food?ECI?of cotton bollworm between the Bacillus safensis feeding treatment and the common artificial feeding treatent?P>0.05?.This study carried out the influence of development,gene function and microbial components of cotton bollworm under continuous elevated CO₂ concentration stress,The characteristics and mechanism of cotton bollworm were study to response continuous elevated CO₂ concentration Also the function of Bacillus safensis AN1 impacts on the nutritional and physiological metabolism of cotton bollworm were studied.This study can provide the data support for the population dynamics of cotton bollworm,which can use for controlling of cotton bollworm in the future incresing CO₂ levels,which also provide new ideas for the development of probiotic feed and bio-pesticides.