EXTRACTION AND BIOASSAY OF FEMALE SEX PHEROMONE OF WHITE-MARKED TUSSOCK MOTH, ORGYIA LEUCOSTIGMA (LEPIDOPTERA: LYMANTRIIDAE)

Factors affecting the extraction and bioassay of the sex pheromone of white-marked tussock moths were evaluated. Dipping the female pheromone glands in a solvent (preferably hexane) to produce a wash containing active material was a particularly effective and reproducible method of obtaining a potent extract. These were most active if obtained from virgin females < 2 days old. Extracts from recently mated females were only slightly less active than those from virgin females. Males were most responsive in bioassays when 2 to 3 days old. The maximum percentage response of males was obtained at 1 × 10−4 FE (female equivalents); beyond this concentration the percentage response decreased. Characteristically, extracts lost their potency within 1–3 weeks of preparation. It is suggested that either an inhibitor or loss of a chemical component of the sex pheromone causes an extract to become inactive.