Effects Of Elevated CO₂ On The Fitness And Symbiotic Bacteria Of Lipaphis Erysimi

In this study,three CO₂ concentrations（400μL/L,600μL/L and 800μL/L CO₂）were set up,and effects of elevated CO₂ on the growth,development and reproduction of multiple generations(1^st,3^rd,7^th,10^th,13^th,16^th generation)of Lipaphis erysimi Kaltenbach were studied.The changes of metabolic enzyme activities in the multi-generation of L.erysimi populations under different CO₂ concentrations were measured.The relative expression differences of stress resistance genes in L.erysimi under different CO₂ concentrations were analyzed.Using 16S r DNA sequencing,the effect of different CO₂ concentrations on the diversity and abundance of symbiotic bacteria of L.erysimi were surveyed.The metabolic differences of L.erysimi to different CO₂concentrations were analyzed by KEGG pathway,and the response of L.erysimi to elevated CO₂were clarified.In order to provide theoretical support for the control of L.erysimi under the condition of increasing atmospheric CO₂ concentration in the future The results are as follows:1.Effect of elevated CO₂ concentrations on individual life history and population parameters of L.erysimiUsing the two sex life table,the effect of three CO₂ concentration on the individual life history parameters of 16 generations of L.erysimi were studied.The experimental results showed that significantly lower adult lifespan and fecundity of the 1^st and 16^thgenerations of L.erysimi were observed under 800μL/L CO₂ treatment than those of400μL/L CO₂ treatment（P<0.05）.Significantly higher nymph duration of the 1^stgeneration of L.erysimi was found in 400μL/L CO₂ treatment compared with 800μL/L CO₂ treatment（P<0.05）.The 16^th generation nymph duration of L.erysimi was significantly lower than those of 400μL/L CO₂ treatment（P<0.05）.However,no significant difference was found im the survival rate of L.erysimi under the three CO₂concentrations（P>0.05）.There were no significant differences in the intrinsic rate of increase（r）,the finite rate of increase（λ）and net reproduction rate（R₀）of L.erysimi between 600μL/L CO₂ treatment and 400μL/L CO₂treatment（P>0.05）.Significantly higher the intrinsic rate of increase（r）and the finite rate of increase（λ）were found under 600μL/L CO₂ concentration treatment relative to 400μL/L CO₂ concentration treatment（P<0.05）.The experimental data showed that 600μL/L CO₂ concentration can promote the individual fitness and the population parameters of L.erysimi.2 Effects of different CO₂ concentrations on nutrient and enzyme activities of L.erysimiThe results of nutritious substances and enzyme activities of L.erysimi under three CO₂ concentrations showed that significantly higher total protein content in the 1^st and16^th generations of L.erysimi was found in 600μL/L CO₂ concentration than those of800μL/L CO₂ concentration（P<0.05）.The content of total amino acids in the 1^st,7^th,16^th generations of L.erysimi was significantly higher in 800μL/L CO₂ treatment than those in 400μL/L and 600μL/L CO₂ treatments（P<0.05）.The catalase（CAT）activity in the 1^st generation of L.erysimi was significantly lower in 400μL/L CO₂ treatment than those in 600μL/L and 800μL/L CO₂ treatments.The total superoxide dismutase（SOD）activity in the body of L.erysimi decreased gradually with the generation prolongation under three CO₂ concentrations.There was no significant difference in SOD activity in the 16^th generation of L.erysimi between 600μL/L CO₂ and 800μL/L CO₂ treatment（P>0.05）.Significantly lower glutathione-S transferase（GST）activities were observed in the 1^st,7^th and 16^th generations of L.erysimi under 400μL/L CO₂treatment compared with 600μL/L CO₂ treatment（P<0.05）.The results indicated that600μL/L CO₂ concentration can increase detoxification enzymes activities,which could increase the defense ability of L.erysimi against the increase of atmospheric CO₂concentration in the future.3 Effects of different CO₂ concentrations on the growth and development of L.erysimi and the expression of stress-resistant genesThere were no significant difference in relative expression levels of vitellogenin（Vg）and vitellogenin receptor（Vg R）in the body of L.erysimi under different CO₂concentrations（P>0.05）.However,the relative expression of Vg in the body of L.erysimi in 600μL/L CO₂ was higher than that in 400μL/L treatment,which indicated that 600μL/L CO₂ concentration can promote the reproduction of L.erysimi.Significantly higher HSP70 and HSP83 genes were found in the body of L.erysimi under 800μL/L and 600μL/L CO₂ treatments than those in 400μL/L CO₂ treatment（P<0.05）,which indicated that elevated CO₂ could stimulate the expression of HSP70and HSP83 genes in the body of L.erysimi.It is speculated that the relative expression of heat shock protein genes in the body of L.erysimi can be promoted when the atmospheric CO₂ concentration reaches 600μL/L in the middle of this century.L.erysimi populations can resist future global warming by increasing the expression of stress resistance genes.4 Effects of different CO₂ concentrations on symbiotic bacteria in L.erysimiUnder the high CO₂ concentration treatments,lower OTU value of symbiotic bacteria was found in the body of L.erysimi than those in 400μL/L CO₂ treatments.The higher of Buchnera abundance was found in the body of L.erysimi under 600μL/L CO₂ than those of 400μL/L and 800μL/L CO₂ treatments,while the higher of Acinetobacter abundance was found in the body of L.erysimi under 800μL/L CO₂treatment than those in 400μL/L and 600μL/L CO₂ treatments.The results of KEGG metabolic pathway showed that elevated CO₂ promoted the amino acid and lipid metabolism in the body of L.erysimi,and increased the number of pathway function genes in the body of L.erysimi.There was positively correlation in the growth parameters and symbiotic bacteria,such as Buchnera,Bacteroides,Prevotella under different CO₂ concentrations.The Acinetobacter in L.erysimi was negatively correlated with fecundity,r,λand R₀,indicating that the Acinetobacter is an important symbiosis in the body of L.erysimi.Acinetobacter can inhibit the growth and population outbreak of L.erysimi in the future climate warming.CO₂ concentration of 600μL/L accelerated the growth and development of a L.erysimi individuals and population reproduction,and promoted the outbreak and damage of L.erysimi populations.The results provide theoretical support for the prevention and control of aphid radish under future climate warming.