Evaluation of Bacterial Communities of <i>Listronotus maculicollis</i> Kirby Reared on Primary and Secondary Host Plants.

Abstract

The annual bluegrass weevil (<i>Listronotus maculicollis</i> Kirby) is a devastating insect pest of annual bluegrass (<i>Poa annua</i> L.) and, to a lesser extent, creeping bentgrass (<i>Agrostis stolonifera</i> L.) on golf courses. <i>Listronotus maculicollis</i>-reared <i>A. stolonifera</i>, a comparatively tolerant host, incurs fitness costs, including longer developmental periods and reduced larval survivorship. This study sought to characterize microbiota diversity in <i>L. maculicollis</i> adults and larvae reared on <i>P. annua</i> and <i>A. stolonifera</i> cultivars (Penncross & A4) to explore whether intrinsic factors, such as microbial community composition, vary across host plants and developmental stages, potentially influencing host suitability. Alpha diversity analyses showed adults feeding on A4 exhibited higher bacterial species richness than their offspring reared on the same cultivar. Beta diversity analysis revealed significant dissimilarities between <i>L. maculicollis</i> adults and offspring regardless of host. <i>Pseudomonas</i> sp. was consistently abundant in larvae across all turfgrasses, indicating a potential association with larval development. Elevated levels of <i>Wolbachia</i> sp., known for insect reproductive manipulation, were observed in adults, but appear to be unrelated to host plant effects. The most prevalent bacterium detected was <i>Candidatus</i> Nardonella, a conserved endosymbiont essential for cuticular hardening in weevils. Given the role of cuticular integrity in insecticide resistance, further investigations into insect-microbe-plant interactions could guide the development of targeted pest management strategies, reducing resistance and improving control measures for <i>L. maculicollis</i>.