Pheromone-mediated behavior of the gypsy moth

The pheromone-mediated behavior of gypsy moth males was studied in both natural and simulated populations in central Pennsylvania. Feral males released into 50-m-diam plots, each with 2 feral females around the perimeter, oriented initially to trees and not to females. Neither exposure to virgin females nor exposure to wicks baited with approx 6 mg disparlure affected the subsequent sexual activity of males released into the 0.2-hectare plots. Males released into untreated plots, following 24 hr exposure in an area treated with approx 37 g/hectare of microencapsulated disparlure, located and mated with feral females within 4 min after release. None of the released males was caught in disparlure-baited Delta traps. In the disparlure-treated plot none of the females was mated. Males within this treated plot continued to search actively but did not settle down on the bark surface and initiate short-range (< 15 cm) search behavior. In plots testing the effect of various ratios of baited wicks to virgin females on disruption, there was no evidence of mating disruption due to point-source confusion. There were no significant differences in the responses of feral males to either virgin females or the various portions of Hercon wicks placed out in 0.2-hectare plots. In a series of tests using feral virgin females given various treatments to alter their physical and chemical characteristics (i.e., removed wings, denuded abdomen, washed in xylene, etc.), all females elicited the full range of sexual behavior responses of the male moths in natural populations. Apparently, males stimulated by pheromone are capable of using a number of different additional stimuli to initiate and terminate short-range sexual behavior patterns.Lymantria dispar (L.); Lymantriidae: Lepidoptera.Authorized for publication on April 19, 1976 as paper no. 5066 in the journal series of the Pennsylvania Agricultural Experiment Station, Experiment Station Project No. 2044.