Sex pheromones of noctuid moths. VII. Quantitative aspects of the production and release of pheromone by females of Trichoplusia ni (Lepidoptera: Noctuidae).

Abstract

Ether extracts of the terminal abdominal segments of females of Trichoplusia ni (Hubner) (Lepidoptera: Noctuidae) were assayed for sex pheromone activity by gas-liquid chromatography and by bioassay. No pheromone was found in female pupae. Immediately following the moths' emergence from the pupa approximately 0.01 µg of sex pheromone per female moth was detected. The amount increased to approximately 0.2 µg on the first night following emergence, and stabilized at approximately 1 µg on the second through sixth nights. No correlation was found between the quantity of sex pheromone per female and the time of day at which they had been collected and extracted. The sex pheromone level remained high among females that had mated; this fact is consistent with observations that T. ni females characteristically mate more than once. The quantity of sex pheromone in mature females was positively correlated with their initial weights. No evidence was found indicating the presence of a sex pheromone or pheromone-potentiator in any area of the female body except the terminal abdominal segments. The T. ni sex pheromone volatilizes rapidly from filter paper, having a half-life retention time of approximately 8 minutes. The sex pheromone released by individual living T. ni females stimulated more males than did filter papers impregnated with extract equivalent to 1 female. However, no reduction has been detected in the amount of sex pheromone remaining in females that have been releasing the pheromone for up to 30 minutes.