| Abstract/Contents: | "Objectives: 1) Evaluate the role of ants as beneficial predators in golf turf; determine the predominant species inhabiting golf courses; and develop tactics for managing mound-building pest ants on putting greens with reduced environmental risk or impact on beneficial species.; 2) Investigate synergism between endophyte-enhanced, resistant turfgrasses and biorational insecticides for improved management of white grubs and black cutworms.; 3) Examine the main and interacting effects of cultural practices (mowing height, irrigation, and N fertilization) on nutritional and defensive characteristics of creeping bentgrass, and on relative susceptibility to white grubs and black cutworms.; 4) Identify the sex pheromone of northern and southern masked chafers (Cyclocephala spp.) and explore practical uses for the pheromone in golf courses settings. Conservation of naturally-occurring biological controls is important for reducing need for insecticide usage on golf courses. Ants, the most abundant insects inhabiting turfgrass, are highly efficient predators on eggs and larvae of cutworms, grubs, and other pest insects. On golf courses, however, the positive aspects of ant predation must be weighed against the fact that same species build nests and mounds on putting greens and tees. This research seeks to identify beneficial and armful ant species, document their significance, and develop effective means for controlling pest ants while conserving useful, predatory species. Surveys of ants inhabiting roughs, fairways, tees, and putting greens of central Kentucky golf courses revealed that virtually all of the mound-building problems in close-cut creeping bentgrass are caused by one species, Lasius neoniger. Lasius appears to be the major nuisance ant on golf courses throughout much of the U.S. Surface insecticides usually won't eliminate these ants because they fail to reach the ground-nesting queen. We evaluated two novel approaches for suppressing mounding activity on tees and greens. The first involved use of target-selective ant baits, some of which already have revolutionized ant control tactics used by the structural pest control industry. After testing seven candidate baits for acceptability to Lasius, we selected the three most attractive ones for evaluation on golf courses. These baits contained as active ingredients either avermectin (Advance® Granular Carpenter Ant Bait; WhitMire Micro-Gen, Inc.) hydramethylnon (Maxforce® granular ant bait; Clorox, Inc.), or spinosad (NAF-464; Dow AgroSciences). Each has a different, insect-specific mode of action, low mammalian toxicity, and favorable environmental characteristics. Advance® and MaxForce® already are labeled for use on turfgrass sites. Field trials on golf tees showed that use of these baits will provide rapid, 80-95% elimination of Lasius mounds and nests, either by broadcast, or by selective application from a shaker can. In another study, fipronil (Chipco Choise®, Rhone-Poulenc, Inc.) was found to be effective for season-long suppression of Lasius nests and mounds on putting greens. This novel phenyl pyrazole, characterized by low mammalian toxicity and very low use rates, is a promising candidate for ant management on golf courses. Field experiments demonstrated that Lasius neoniger and other ant species are very important in suppressing other insect pests. In trial after trial on roughs, fairways, or putting greens, ants eliminated large numbers of eggs and young larvae of black cutworms, and eggs of Japanese beetle. This underscores the wisdom of selective, rather than fence-to-fence, management of nuisance ants where mound-building becomes a problem. Fortunately, our related work with halofenozide (Mach 2) and imidacloprid (Merit) has shown that these powerful new insecticides are compatible with preservation of beneficial species, including ants. Our second objective concerns whether use of insect-resistant grasses in combination with reduced-risk insecticides can provide levels of control previously possible only with more broad-spectrum pesticides. In 1998, we studied possible synergistic or antagonistic interactions between endophytic perennial ryegrass and efficacy of Bacillus thuringiensis (Bt), Bacillus popilliae (milky disease bacteria), and spinosad (Conserve®). We sought to determine if the sublethal stress endured by pests feeding on endophytic grass might enhance the activity of these products. Dose-mortality studies with Bt and spinosad were conducted with black cutworms fed on either endophytic (E+) or non-endophytic (E-) grass. Even full label rates of Bt provided no suppression of cutworms, irrespective of endophyte level. Spinosad provided 100% control, even at 1/4 label rate, on both E+ and E- grass. Dose-mortality studies with milky disease and Japanese beetle grubs showed significant rate effects, but disease incidence was not affected by endophyte level. Finally, progress continued toward identifying the female sex pheromone of northern and southern masked chafers, the most destructive native grubs species in the U.S. A synthetic bait would be useful for monitoring, fine-tuning treatment schedules, or assessing local grub densities on golf courses. Earlier, we discovered that the pheromone also is present in the grubs. In 1998, ≅10,000 grubs were dug from Kentucky golf courses for pheromone collection. The grubs were rinsed in hexane to remove the pheromone; extracts were sent to collaborators (A. Attygalle, J. Meinwald, Cornell University) for analysis. The chemical peak representing the pheromone was pinpointed by gas chromatography and electroantennogram analysis, and its molecular weight was determined. Gas phase IR was used to further characterize the compound's structure. Hopefully, the identification can be completed this winter, so that field testing during beetle flights can begin in 1999." |
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