Detection of Listronotus maculicollis (Coleoptera: Curculionidae) Turfgrass Canopy Activity With the Use of a Novel Fluorescent Marking System Suggests Opportunities for Improved Mechanical Control.

The annual bluegrass weevil, Listronotus maculicollis Kirby, is a severe pest of short-mown turfgrasses in eastern North America. Previous research has demonstrated that adults can be removed from golf course putting greens during mowing. However, the impact of mechanical control on adult removal diminishes with increases in mowing height. Therefore, to optimize adult removal we sought to describe adult presence on top of the turfgrass canopy to identify periods when mowing would be most effective. Growth chamber studies using time-lapse photography revealed that greatest activity occurred between 15 and 20°C, with few weevils active on the surface when temperatures were less than 10°C. A mark-release technique combining fluorescent marks with still photography was used to assess adult movement in the field. This novel mark-recapture system confirmed laboratory findings that adult activity on top of the turfgrass canopy was greatest during the day and strongly correlated with temperature early in the season (April, May). However, adult presence on the surface in early summer was greatest briefly after sunrise, then declined during the mid-morning when temperatures exceeded 21°C. The effect of temperature on surface activity was best described by a second-order polynomial function, which predicts maximum adult surface activity between 14 and 17°C. Our findings suggest that adult surface activity is strongly associated with temperature and not photophase, and therefore, monitoring populations and scheduling mowing with the intent to remove adults need to be adjusted seasonally with changes in temperature.