Biology and Control Of The Annual Bluegrass Weevil On Golf Courses
Dr. Patricia Vittum, University of Massachusetts, 4 years ($21,200, $25,090,
$25,630, $15,390)
Objective(s): Dr. Vittum began this study in the summer of 1999 to refine our
understanding of the biology of the insect, number of generations, over wintering sites,
feeding preferences, and determining whether the insect is nocturnal or diurnal. She plans
to investigate non-traditional management approaches and products. Develop a refined
degree day model to assist in the prediction of larval activity.
1999 Results: 1. Turf samples were collected from late April through August, when the
larvae were expected to be active at several locations, and daily air temperature data was
recorded to begin to develop a degree day model. 2. Over wintering sites are being
evaluated other than White Pine litter to see if other sites are regularly used by the insect
adults. 3. Adult reproductive monitoring and feeding preferences are being evaluated to
help understand the biology and cycles the ABW has. 4. A small field trial using
Entomopathogenic Nematode against the weevil adults is also being evaluated.
2000 Results: Hyperodes Weevil (Listronotus masculicollis) is a known pest in highly maintained turfgrass throughout the Northeastern United States. The research will include studies to confirm the Hyperodes feeding preference theory of Poa annua. Research plots on Dunwoodie Golf Club of Yonkers, NY, showed differences between populations on Poa annua vs Creeping Bentgrass were not significantly different. At Minnesceongo Country Club, Pomona, NY, it was found true that Hyperodes prefer Poa annua at the same height under actual golf course conditions. It maybe that the higher maintenance level on golf courses make Poa the optimal grassplant for Hyperodes larvae.
The 2001 season should supply enough information to understand the life history of Hyperodes Weevil. Reproductive, insemination, and hibernation habits will continue to be researched in order to better understand this species and to help prevent future outbreak populations.
2001 Results: During the 2001 growing season, Dr. Vittum's PhD Candidate Nikki Rothwell expanded the work to include reproductive seasonality of adult weevils, refined a growing degree-day model, and set up field sites studying weevil preferences for grass species and mowing heights. Several field trials testing the efficacy of three biological control studies were also setup.
Reproductive Seasonality: Weevils were collected monthly in 2000 and 2001, and dissected to determine their reproductive development to predict degree-days. Some female adults were found to be inseminated in the fall and some in the spring, which should effect control recommendations.
Growing Degree-day Model: Nikki has collected data on daily air temperatures, soil temperatures, and rainfall amounts from several golf courses in the Westchester County area, Vermont, Connecticut and Massachusetts in 2001 to further refine a growing degree-day model to be validated in 2002.
Grass Species Preferences, Mowing Heights and Fertility: Nikki expanded the study to include looking at different heights of cut, grass species and fertility levels and found that under certain agronomic conditions weevil larvae were "very willing to feed on creeping bentgrass plots particularly at lower heights." More larvae were found in turf at lower heights of cut, and less in higher cut turf.
Combining the data and along with some lab tests will determine if the weevil's preference is to lay her eggs in Poa Annua.
Fairway Transects: Were set-up to test if more insects were along the edges of fairways than in other areas of the fairway. It was found that there were no significant differences between the center of the fairway and along the edges.
Non-chemical Control Alternatives: Three non-chemical controls were applied to the plots and it was found that they were mostly ineffective. The products were Heterorhabditis bacteriophora (nematode), spinosad (Conserve), Bacillus thuringiensis (Novodor).
2003 plans to repeat the turf species/mowing height/ fertility study and transect study and to make further field observations on weevil behavior.
