USA research to help with Stem Weevil

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A new step forward in managing a pernicious pest of golf course putting greens comes with an assist from an unlikely source: marine biology.

Researchers at Penn State University’s Center for Turfgrass Science have been seeking to improve management methods for the annual bluegrass weevil (Listronotus maculicollis), but a key challenge is to determine when the insects are most active in the grass canopy. Mowing putting greens can remove some of the weevils, and timing the mowing for the weevils’ active foraging period might remove more of them. But the weevils are small (at most 4.5 millimeters long) and difficult to monitor, says Benjamin McGraw, Ph.D., associate professor of turfgrass science at Penn State. So McGraw and then-Master’s student Benjamin Czyzewski needed a way to make the weevils easier to see, during both night and day.

Their first attempt ran into trouble. They marked weevils with fluorescent ink and placed them in cages with a UV light and a time-lapse camera. “No matter how hard we tried to exclude other insects, nocturnal insects would somehow get in, be attracted to the UV light, and block the time-lapse images,” McGraw says.

So, they went searching for solutions. On the tradeshow floor of the 2015 Entomological Society of America Annual Meeting, McGraw came across NightSea, which makes tools for fluorescent photography and whose founders originally created their equipment for exploring coral reefs and underwater sea life at night. NightSea’s flashes and camera filters block white light and allow fluorescence—whether natural or, in this case, via human-marked ink) to shine.

This led to a new experimental set up, using still photography taken at one-hour intervals instead of time-lapse video, and this time it worked. The results offered a new understanding of the weevils’ daily behavior patterns and are reported in a new article published in October in the Environmental Entomology.