Host plant resistance/tolerance to annual bluegrass weevil (Listronotus maculicolis) in turfgrass

Annual bluegrass weevil (ABW), Listronotus maculicolis, is a damaging and difficult-to-manage pest of cool season, short-mown turfgrass, due to its multi-generation life cycle with asynchronous developmental stages. The ABW have long been known to have a feeding preference for annual bluegrass (Poa annua) but have increasingly been observed damaging creeping bentgrass (Agrostis stolonifera) especially in the absence of their primary host. In this study, we compared the larval survival rate and turf damage level between 25 commercially available bentgrass cultivars and annual bluegrass under greenhouse conditions. Adult weevil mating pairs were caged onto turfgrass pots and allowed to lay eggs for 1 week before removal. Larvae were left to develop in turfgrass for 4 weeks, after which samples were destructively processed to extract all stages using 10% saline solution. Larvae counts and instars were evaluated across all cultivars. To assess damage levels, turfgrass quality was evaluated via both visual ratings and digital image analysis at the beginning and end of test. Varying with cultivars, some bentgrass are expected to tolerate more damage and support less insect development. This study will improve our understanding of which bentgrass cultivars are most resilient to ABW damage and allow turf growers to incorporate host plant resistance into IPM strategies and combat pest infestations in a more sustainable manner.