Insight into the routes of Wolbachia transmission: Myrmecophily and horizontal transmission

While phylogenetic studies have implicated frequent horizontal transmission of Wolbachia from one species to another, ecological determinants of such lateral transfer are poorly known. We argue that intimate contacts between social insect and their guests provide opportunities for Wolbachia horizontal transmission. In this study, we examine kleptoparasitism (i.e. food-stealing) as a potential mechanism for Wolbachia horizontal transmission using ant crickets and their host ants as the model system. We compared prevalence and diversity of Wolbachia across multiple ant cricket species with different degrees of host specificity and integration level. Our analyses revealed at least three cases of inter-ordinal Wolbachia transfer among ant and ant crickets, and also showed that ant cricket species with high host-integration and host-specificity tend to harbor a higher Wolbachia prevalence and diversity than other types of ant crickets. This study provides empirical evidence that distribution of Wolbachia across ant crickets is largely attributable to horizontal transmission, but also elucidates the role of intimate ecological association in successful Wolbachia horizontal transmission.