You are what you harbour: contrasting microbial communities detected in parthenogenetic and sexual weevils

Abstract

Relationships between insects and microbiota have profound effects in the biology of interacting partners. Previous results in weevils from the tribe Naupactini showed that species reproducing parthenogenetically are infected with high loads of Wolbachia pipientis, while sexually reproducing ones are infected with low densities or uninfected. In this work, we aimed to deepen the study of the main facultative symbionts in four Naupactini species. The results showed different profiles depending on the reproductive mode: parthenogenetic weevils had Wolbachia and Rickettsia sp. as main endosymbionts, while in sexual species the dominant bacteria was Spiroplasma spp. Furthermore, sexually reproducing species showed much more diverse bacterial communities than those hosted by parthenogenetic weevils. For all hosts, the three dominant symbionts were scattered across the whole body. Thus, both bacterial pairs (Wolbachia/Rickettsia sp. and Wolbachia/Spiroplasma spp.) were observed in the same tissues. Considering the previously reported link between Wolbachia and Naupactini weevil’s reproduction, this initial investigation allows us to hypothesise that, under certain conditions, the resident microbiota might restrict Wolbachia loads. The actual roles of endosymbionts in weevil’s biology related to host reproduction remain an open question that warrants further study.