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Title: EFFECTS OF INTENTIONAL GAPS IN SPRAY COVERAGE ON THE EFFICACY OF GYPSY MOTH MATING DISRUPTION

Author
item TCHESLAVSKAIA, K.S. - VA. TECH
item BREWSTER, C.C. - VA. TECH
item THORPE, KEVIN
item SHAROV, K.W. - VA. TECH
item LEONARD, D.S. - USDA, FOREST SERV.
item ROBERTS, E.A. - VA TECH

Submitted to: Journal of Applied Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/21/2005
Publication Date: 9/2/2005
Citation: Tcheslavskaia, K., Brewster, C., Thorpe, K.W., Sharov, K., Leonard, D., Roberts, E. 2005. Effects of intentional gaps in spray coverage on the efficacy of gypsy moth mating disruption. Journal of Applied Entomology. 129(9-10):475-480.

Interpretive Summary: The gypsy moth is the most serious pest of hardwood trees in the northeastern United States. To slow the rate at which this pest is spreading to the west and south, the United States Department of Agriculture (USDA) conducts a Slow-the-Spread of the Gypsy Moth program (STS) along a 1,200 mile front which extends from North Carolina to Wisconsin. The primary control tactic used in STS is mating disruption because it is highly effective and has no unintended environmental impacts. Mating disruption involves the aerial application of synthetic gypsy moth sex pheromone to prevent moth mating. While the tactic is highly effective, aerial application of mating disruptants is costly and funds are limited. Therefore, improvements in cost effectiveness of the method would be desirable. Previous research showed that gypsy moth mating is disrupted beyond the edges of treated areas. This finding led to the efforts reported here to determine if deliberate gaps in pheromone spray coverage could reduce flight time and distance without reducing effectiveness. When a single swath, or aircraft path, was left untreated, mating was disrupted in the unsprayed areas to the same degree that it was in the treated areas. However, when three swaths were left untreated between treated swaths, mating disruption was not effective in the unsprayed areas. Alternating treated and untreated swaths provides an option for gypsy moth mating disruption treatments that could reduce application costs by reducing flight time and fuel costs without reducing effectiveness. The information presented in this report will provide guidance to government agencies, gypsy moth control specialists, and other persons interested in gypsy moth mating disruption programs.

Technical Abstract: Forested plots in Virginia, USA were treated aerially with a gypsy moth, Lymantria dispar (L.) (Lepidoptera: Lymantriidae), mating disruption formulation to determine if intentional gaps in coverage resulted in reduced efficacy. Capture of gypsy moth males in pheromone-baited traps and female mating success were significantly reduced in plots treated with Disrupt II, a plastic laminated flake formulation of racemic disparlure, at an overall application rate of 37.5 g of active ingredient/ha but with untreated gaps of 30 m or 90 m between 30-m wide treated swaths. In one of two plots with 90 m gaps, significantly more males were captured in traps in the untreated areas compared to those in treated areas within the plot. However, in the other plot with 90 m gaps, significant differences did not occur. No difference in male moth capture was observed between treated and untreated areas with 30 m gaps between treated swaths. These results suggest that it may be possible to lower costs associated with gypsy moth mating disruption applications by alternating 30 m treated and untreated swaths, which would reduce flight time and fuel costs, without a reduction in efficacy.