Nardonella endosymbiont in the West Indian sweet potato weevil Euscepes postfasciatus (Coleoptera: Curculionidae)

The West Indian sweet potato weevil, Euscepes postfasciatus, is a notorious pest of the sweet potato, Ipomoea batatas. We examined the potential presence of a bacterial endosymbiont in the pest weevil. The bacterial 16S rRNA gene and groEL gene were detected by PCR from the insects. Cloning, sequencing and molecular phylogenetic analyses of the bacterial genes demonstrated that E. postfasciatus is associated with a gamma-proteobacterial endosymbiont of the genus Nardonella. In situ hybridization detected the endosymbiont in the female ovaries, indicating its transovarial transmission through host generations. This study is the first to identify Nardonella from the weevil subfamily Cryptorhynchinae. The potential relevance of the endosymbiont in the biology and management of E. postfasciatus is discussed.