Combined Effects And Mechanisms Of Elevated CO₂ Concentration And Endosymbiotic Wolbachia Infection On Hylyphantes Graminicola?Araneae: Linyphiidae?

The effects of ecological environment caused by the instantly rising atmosphere CO2 concentraion have attractived more and more attention.At present,there are many research concerning about elevated CO2 concentraion affect on paints,phytophagous insects and the interaction effects between plants and insects.Wolbachia,an endosymbiotic bacterium,widespreadly in insecta and arachnida,have important effects on growth,development and reproduction.Hylyphantes graminicola,is one of domain species in the fielded of maize and cotton.Our experimental material was H.graminicola.According to CO2 concentration and Wolbachia status,we divided H.graminicola into four treatments:W-(Wolbachia-uninfected)400 ppm(ambient atmosphere CO2 concentration),W-800 ppm(high CO2 concentration,2-fold of ambient atmosphere CO2 concentraion),W+(Wolbachia-infected)400 ppm,and W+800.Combined effects and mechanisms of elevated CO2 concentraion and Wolbachia infection on the survival rate,growth and development,propagation of H.graminicola were researched.At the same time,to clarify the molecular mechanism of the combined effects of elevated CO2 concentration and Wolbachia infection,the transcriptome and difference expression of stress-related genes under different treatment were researched.Combined effects and mechanisms of these 2 factors can not only expore the reproductional regulation and propagation but also enrich the effects of theoretical research of predatory enemy field,moreover,give theoretical evidences for spider's protection and effectively utilization for agriculture pests biological control.Our main research contents and results are as follows:1.Combined effects of elevated CO2 concentration and Wolbachia infection on survival rate,growth and developmet,propagation of H.graminicola.F1 generation of H.graminicola which have known Wolbachia status were reared under different CO2 artificial climate box,the days from second instar to adult were recorded,the data of survival rate,sex ratio,carapace size,weight and oviposition were recorded.Our results showed that no combined effects of elevated CO2 concentration and Wolbachia-infection on survival rate of H.graminicola(P>0.05).Although in Wolbachia-uninfected spiders,the total developmental duration was not variant under different CO2 concentration(female:P = 0.402;male:P =0.690),Wolbachia-infected spiders significantly decreased developmental duration(female:P<0.0001;male:P = 0.009).Elevated CO2 could significantly decrease the width of carapace(P<0.0001),but no obvious effects on carapace length.There were no significant effects on carapace length and width affected by Wolbachia-infection(P>0.05).The combined effects of these 2 factors significantly shorten the carapace length and width(P<0.05).There were no significant effects on body weight sex ratio,net reproductive rate under elevated CO2 concentration or Wolbaechia-infection and the interaction of these two factors was not found(P>0.05).2.Combined effects of elevated CO2 concentration and Wolbachia-infection on nutrition content and digestive and protective enzymes activity ofH.graminicola.Adult spiders were randomly selected from every treatment and detected with test kits,with 5 biological replications on every treatment.Our studies found that the level of total amino acid was not significantly affected in Wolbachia-uninfected female spiders reared under high CO2 concentration(P = 0.496),while it was significantly increased in Wolbachia-infected female spiders(P<0.0001).The levels of protein,specific activities of amylase and peroxidase were increased significantly under elevated CO2 concentration or Wolbachia-infected spiders(P<0.05).The combined effects of these 2 factors significantly increased the levels of total amino acid,protein,specific activities of peroxidase and amylase(P<0.0001).3.Combined effects of elevated CO2 concentration and Wolbachia-infection on transcriptome and stress-related gene expression of H.graminicola.Female adult spiders were randomly selected from every treatment and were freezed for transcriptome sequencing,with 3 biological replications on every treatment.Differentially expressed genes(DEGs)were filtered,then stress-related genes were selected for RT-qPCR detection.The results of transcriptome sequencing showed that,84 DEGs were found because of elevated CO2 concentration(W-400 VS W-800),including 74 up-regulated and 10 down-regulated genes,which enrich in "carabohydrate and metabolism","catalytic activity" pathways.Between Wolbachia-infected and Wolbachia-uninfected treatment(W-400 VS +400),21DEGs were found,including 13 up-regulated and 8 down-regulated genes,which enrich in "response to stimulus" and "phagosome".In addition,157 DEGs were detected in Wobachia-infected spiders reared under high CO2 concentration(W-400 VS W+ 800),including 64 up-regulated and 93 down-regulated genes,which mainly enrich in "catalytic activity","metabolic process" and "phagosome".The results showed that combined effects of these 2 factors have strong effects on metabolism and catalyze process of H.graminicola.From the Unigene which were mapped with GO,KEGG and other databases,we filtrated 8 DEGs which under the stress of elevated CO2 concentration and Wolbachia-infection,to test by RT-qPCR,and expression of DEGs were in line with transcriptome sequencing(the expression of DEGs in up-relation or down-regulation),suggesting that in order to suit the elevated CO2 concentration and Wolbachia-infection,the expression of stress-ralated genes on H.graminicola were significantly changed.