Coevolution between hosts and parasites is driven by the reciprocal evolution of infectious ability of parasites and host resistance against it. Theory predicts that the vertically transmitted symbiont should evolve toward mutualism. However bacteria of the genus Wolbachia are known as reproductive manipulators of their hosts. When infected males are crossed with uninfected females, cytoplasmic incompatibility (CI) occurs resulting in high mortality of their offspring. The CI gives infected females a reproductive advantage and allows Wolbachia spread rapidly in a host population.

Here we report a countermeasure trait of hosts against the Wolbachia manipulation in Callosobruchus analis (Coleoptera: Chrysomelidae). C. analis is infected with one or two Wolbachia strains. CI is induced by one of them. We found that fecundity and longevity of black mutant females were deteriorated only when those were infected with the CI-inducing Wolbachia. We discuss the possibility that being black could prevent the proliferation of the CI-inducing Wolbachia strain in C. analis.