Mowing Height Influences Listronotus maculicollis (Coleoptera: Curculionidae) Oviposition Behavior and Mechanical Removal from Golf Course Putting Greens, but Not Larval Development

The annual bluegrass weevil, Listronotus maculicollis (Kirby), is a highly destructive pest of golf course turfgrass in eastern North America. Previous research has demonstrated that females prefer to oviposit within short-mown turfgrasses (<1.25 cm), and these offspring have improved fitness traits compared with larvae developing in higher-mowed turf. However, damage to putting green turf (<3.55 mm) is rarely reported. We investigated whether this phenomenon was due to adult removal through mowing or an inability of larvae to develop within a shortened plant. Greenhouse studies revealed that between 26% and 38% of adults were removed when turf was mowed at 2.54 mm (0.100 in), but the effect diminished with increasing mowing heights. The majority of adults survived mowing, indicating a potential for adults to reinvade turf stands adjacent to areas where grass clippings are discarded. Females oviposited in all mowing height treatments in laboratory and field experiments. However, behavior was influenced by plant height, as significantly fewer eggs were placed inside of the turfgrass stem at the lowest mowing height. Larval development was not affected by egg placement or turf height, and significant numbers of larvae were capable of developing to damaging stages (fourth- and fifth-instar larvae) in all treatments. Our findings suggest that L. maculicollis poses a threat to putting green-height turf, but the probability of damage occurring and need for insecticide applications may be lessened on low-mown surfaces. Future studies are needed to determine factors that influence L. maculicollis movement within the turfgrass canopy to optimize mechanical control.