We tested the hypotheses 1 “Endosymbiotic diversity in a host insect affects parasitoid (predator) species diversity” and 2 “Endosymbiotic diversity in a host affects densities and persistence of host and parasitoid populations under climate change and therefore affects resource mass”, using laboratory host–parasitoid(s) systems. We introduced either one or two species of parasitoids, Heterospilus prosopidis and Anisopteromalus calandrae, to a host population, a bruchine beetle feeding on azuki beans, infected by either one or two strains of the endosymbiont Wolbachia. The number of emerged adults, weight of remaining beans, and population extinction were monitored under control or climate change (+ 2 ℃ and double concentration of CO2) conditions for up to 210 days. Wolbachia diversity affected the density of a parasitoid population and the time to extinction of a species in a single-parasitoid system. The host went extinct earlier in a single-parasitoid and two-parasitoids systems. Percentage bean mass that remained uninfested by the host was affected by the climate change and parasitoid diversity but not by Wolbachia diversity. The results partly support both hypotheses and indicate that endosymbiotic diversity can impact populations at a higher trophic level, irrespective of climate, but not a population at a lower trophic level.