Study On Effects Of Two Endosymbionts On Reproduction And Fitness Of A Pest And A Predatory Mite

To clarify the effects of Cardinium and Wolbachia on the reproductive traits and fitness of two infected mite species Tetranychus turkestani and Neoseiulus Californicus,the experiments were performed in the lab populations of the two mites.The experimental populations of double-infected and single-infected mites were obtained by screening and continuous rearing,and the uninfected were obtained by treatment with 0.3% tetracycline solution.Different cros s combinations were made to explore effects of the two symbiotic bacteria on reproduction of Tetranychus turkestani and Neoseiulus Californicus,meanwhile comparison of relevant parameters was made between the infected and uninfected respectively to study the effects of Cardinium and Wolbachia on fitness of Tetranychus turkestani and Neoseiulus Californicus.The main results were as follows:1.Cytoplasmic incompatibility(CI)was induced by both single-infection and double-infection of Cardinium and Wolbachia in Tetranychus turkestani: The former showed a decline in fecundity,the number of F1 females and percentage of F1 females while the latter showed a decline in hatching rate,survival rate,number of F1 females and percentage of F1 females.Cardinium and Wolbachia could also influence fitness of T.turkestani by shortening lifespan and developmental durations.Furthermore,when infected with Cardinium and Wolbachia,the CI could be even stronger.Cardinium and Wolbachia had no influence on CI strength or rescue of the other.2.Cytoplasmic incompatibility(CI)was induced by both single-infection and double-infection of Cardinium and Wolbachia in Neoseiulus Californicus: Single infected with Cardinium and Wolbachia could induce strong CI in Neoseiulus Californicus.When Cardinium-infected males crossed with uninfected females,fecundity of female adults,hatching rate,survival rate,the number of F1 females and percentage of F1 females were all decreased.Crosses between the Wolbachia-infected males and uninfected females led to decline in hatching rate,survival rate,the number of F1 females and percentage of F1 females,but it didn’t affect female fecundity.Double-infection could also induce CI,and both endosymbionts could affect inducing and rescue ability of the other.Meanwhile,both Cardinium and Wolbachia could affect the fitness of Neoseiulus Californicus.In summery,the endosymbionts Cardinium and Wolbachia could regulate reproduction of Tetranychus turkestani and Neoseiulus Californicus by inducing CI,and impact population fitness of the two different mites simultaneously,thus affecting their population dynamics.