Characterizing the microbiome of Listronotus maculicollis Kirby larvae reared on three varieties of turfgrass

The annual bluegrass weevil (Listronotus maculicollis) is the most destructive pest of short-mown turfgrass in eastern North America. It is found on annual bluegrass and creeping bentgrass at equal densities, but damage is far more pronounced on annual bluegrass. Given the frequent associations between weevils and bacterial endosymbionts, this study aimed to investigate the microbiome of the L. maculicollis reared on their primary and secondary host plants. Total DNA of adults and larvae was extracted, the bacterial 16S rRNA genes amplified, and sequenced via MiSeq. The overall microbiomes were significantly different between turfgrass varieties and between life stages, driven by a few key taxa. All weevils prominently featured Candidatus Nardonella, an intracellular, obligate mutualist of many weevils involved in cuticle hardening. Adult weevils had a significantly greater abundance of Wolbachia, a common reproductive symbiont of many insect species. Conversely, Pseudomonas was significantly elevated in all larval samples, potentially playing a role in the stem-boring, crown-feeding stage of this insect. Other bacterial taxa like Klebsiella and Aeromonas were dominant in larvae reared on the primary and secondary host plant, respectively. Further studies are needed to determine the specific role these bacteria play in the development and survival of annual bluegrass weevil on different host plants. By identifying key taxa involved in larval development on different hostplants, we can expand the number of potential targets to better manage this insect pest.