Wolbachia induce cytoplasmic incompatibility and affect mate preference in Habrobracon hebetor to increase the chance of its transmission to the next generation.

Abstract

Wolbachia are common intracellular bacteria that are generally found in arthropods, including a high proportion of insects and also some nematodes. This intracellular symbiont can affect sex ratio with a variety of reproductive anomalies in the host, including cytoplasmic incompatibility (CI) in haplodiploids. In this study, we questioned if the parasitoid wasp, Habrobracon hebetor (Hym.: Braconidae), an important biological control agent of many lepidopteran larvae, is infected with Wolbachia. To test this, DNA was extracted from adult insects and subjected to PCR using specific primers to Wolbachia target genes. The results showed a high rate of Wolbachia infection in this parasitoid wasp. To determine the biological function of Wolbachia in H. hebetor, we removed this bacterium from the wasps using antibiotic treatment (cured wasps). Results of crossing experiments revealed that Wolbachia induced CI in H. hebetor in which cured females crossed with infected males produced only males, while both male and female progeny were observed for other crosses. Also, we showed that the presence of Wolbachia in females increased fecundity and female offspring of this parasitoid wasp. The presence of Wolbachia in the males had no significant effect on fecundity and female production, but might have incurred costs. We also investigated the effect of Wolbachia on mate choice and found that Wolbachia affects mating behavior of H. hebetor. Together, we showed that Wolbachia induces CI in H. hebetor and affects host mating behavior in favor of its transmission. Wolbachia utilize these strategies to increase the frequency of infected females in the host population.