Gypsy moth mating disruption: Dosage effects

Abstract

Small (1-hectare) plots in a dense gypsy moth (Lymantria dispar) infestation were treated with 5, 50, or 500 g racemic disparlure, and effects on male trap catch and mating behavior were studied. Capture of males in traps baited with 1, 10, 100, or 1000 μg (+)-disparlure declined as disruptant dosages increased. Traps with high levels of attractant caught moths when capture in those with lower baitings was dramatically reduced. While all disruptant dosages reduced trap catch, it was reducd at least 95% at all attractant levels at the 500-g disruptant application rate. Visual estimates indicated that male moth density was similar in treated and control plots; female mating success was reduced 6.5, 34.5, and 84% in plots with 5, 50, and 500 g/ hectare disruptant, respectively. The duration of precopulatory and copulatory periods was similar for all females that were observed mating, regardless of disruptant treatment. It is proposed that reduced trap catch and female mating success are due to effects of atmospheric synthetic disparlure (disruptant) camouflaging natural attractant point sources.

Monitoring and testing different doses of disparlure for Indian gypsy moth, Lymantria obfuscata, in a temperate region of India (Kashmir Valley)

“…Dose response curve (Fig. 1) was calculated by regression equation as Y=10.41x-10.2, with a regression coefficient (R²=0.9959) of 99%, revealing strong correlation between applied doses (Thorpe et al, 1999) showed decrease in moth capture with increasing doses of disparlure (Schwalbe and Mastro, 1988;Webb et al, 1988), but the results of the present investigation may suggest that the highest dosage is effective even at low population densities of L. obfuscata. Sex pheromone lures have been used to study the behavioral polymorphism of L. dispar (Beroza et al, 1973;Punjabi et al, 1974), but no such studies have yet been undertaken for L. obfuscata.…”

“…They can be used, in combination with other methods, to provide estimates of population densities and to monitor populations for the implementation of envi-ronmentally sound management strategies (Sanders, 1988), with examples including insect pests of forest (Granett, 1974;Shepherd et al, 1985;Evenden, 2005) and agricultural ecosystems (Shelton and Wyman, 1979;Tingle and Mitchell, 1981;Ngollo et al, 2000). Also, disruption of chemical communication between the sexes can also be an option for control (Hussain et al, 2014) Studies have been conducted on the use of disparlure [(Z)-7,8-epoxy-2-methyloctadecane], sex pheromone of L. dispar L., for monitoring population dynamics (Schwalbe and Mastro, 1988;Webb et al, 1988), but no such reports are available for L. obfuscata, which is considered to be one of the most destructive defoliators of hardwood trees in Kashmir. Furthermore, the degree day model for different developmental stages of L. obfuscata is still not available.…”

Control of low-density gypsy moth (Lepidoptera: Lymantriidae) populations by mating disruption with pheromone

“…USDA milk carton traps baited with the standard pheromone dispenser were used in all plots (Table 1) to monitor adult male moth flight (Schwalbe and Mastro, 1988). Generally one trap was placed every 6.2 ha (3-17 traps per plot); three traps were placed in the one plot (C2) that was smaller than 18.6 ha.…”

“…Ground applications of dispaflure at rates of 5, 50, and 500 g/ha, dispensed from plastic laminate tapes in plots with high-density gypsy moth populations, resulted in 6.5, 34, and 84% decreases in mating success, respectively, as measured against controls in small plot tests (Schwalbe and Mastro, 1988). Similar studies with disparlure applied in plastic laminate tape (plastic rope) showed that doses as high as 250 g/ha were insufficient to disrupt mating in isolated, high-density populations in which pretreatment surveys showed that immature stages of gypsy moths averaged over 40 per burlap-banded tree (Webb et al, 1990).…”

Gypsy moth,Lymantria dispar, outbreak in northeast London, 1995 – 2003

“…Although it is impossible to determine the influence of buildings and trees on pheromone plumes generated in such an urbanised area, it remains a possibility that mating disruption occurred as a result of the high density of pheromone traps. The incidence of mating disruption is positively correlated with dose rate, and population suppression by mating disruption is perhaps most effective against relatively sparse, low-density gypsy moth populations (Schwalbe and Mastro, 1988;Webb et al, 1990) and can be used to eradicate small isolated colonies with low population density (Sharov et al, 2002b).…”