Effectiveness of gypsy moth mating disruption from aerial applications of plastic laminate flakes with and without a sticking agent

Abstract

Summary1 The plastic laminate flake formulation, Disparlure II, is currently the only gypsy moth mating disruption product available for aerial application. The elimination of a sticking agent from the formulation would reduce costs, simplify application, and make it possible to apply the product without specialized equipment.2 A test was conducted in wooded plots in Virginia during 1997 and 1998 to determine whether a sticking agent is necessary. Treatment effectiveness was assessed from the rates of male moth capture in pheromone‐baited traps and mating success of both laboratory‐reared and wild females.3 Male moth capture was reduced 75.6 and 92.9% in plots treated with flakes without and with a sticking agent, respectively. The percentage of mated females that produced egg masses with more than 5% fertile eggs was reduced by 86.3 and 99.5% in plots treated with flakes without and with a sticking agent, respectively.4 Moth capture and mating success of laboratory‐reared females did not differ significantly between plots treated with flakes with and without a sticking agent. However, the consistently greater reduction in mating success in both years provides strong evidence that mating disruption is less effective when flakes are applied without a sticking agent. The proportion of wild egg masses collected in 1998 with more than 5% fertile eggs was significantly higher under the no‐sticking agent treatment.5 In special situations where the use of a sticking agent may be problematic, such as in residential areas, the data indicate that a high level of mating disruption is likely to occur even without the use of a sticking agent.

Mating Disruption for the 21st Century: Matching Technology With Mechanism

“…Because the results obtained in 1997 were inconclusive, the efficacy of Disrupt II flakes applied without sticker was tested again in 1998 (Thorpe et al 2000). Twelve 250-acre study plots were established within a continuously-forested area in Augusta and Rockbridge counties, Virginia.…”

The role of Allee effects in gypsy moth,Lymantria dispar(L.), invasions

“…This floods the area with pheromone and consequently chemically inhibits the male moth's ability to locate females (Tcheslavskaia et al 2005;Thorpe et al 2006). This tactic has been shown to be effective in eradicating low-density populations, even though no individuals are actually killed (Thorpe et al 2000;Tobin and Blackburn 2007).…”

Gypsy moth mating disruption in open landscapes

“…First, most previous experimental and operational experience with gypsy moth mating disruption has been in forested areas where the dispensers are applied with a sticking agent and are distributed throughout the canopy. In an earlier experiment, gypsy moth mating was disrupted by the aerial application of flakes to a forest canopy without a sticking agent, even though the flakes fell to the forest floor ( Thorpe et al , 2000 ). In open landscapes lacking a canopy, except for the isolated target trees, most of the dispensers fall to the ground, creating a much different distribution of dispensers than occurs in the forest.…”

“…In the male -female proximity experiment, percent mating success was calculated for all females deployed on a given day in each plot. Because gypsy moth mating disruption treatments sometimes fail to eliminate mating but do reduce the number of fertile eggs to a very low level ( Thorpe et al , 2000 ), mating is considered successful only if the female produces ³ 5% fertile eggs. This definition of mating success is considered to be more biologically relevant because females producing < 5% fertile eggs contribute little to the next generation.…”

“…Similar behaviour also occurs when males encounter areas treated with mating disruptants ( Richerson et al , 1976b ). Based on numerous examples of successful operational and experimental mating disruption treatments on low-density gypsy moth populations in forested areas ( Leonhardt et al , 1996;Thorpe et al , 1999Thorpe et al , , 2000Sharov et al , 2002a;Tcheslavskaia et al , 2005a, b ), it appears that a shift to visual searching in treated areas does not confer a sufficient advantage to males to overcome the effects of treatments. However, in situations where females are concentrated on isolated trees in open areas, a visual searching strategy could be more advantageous to searching males.…”