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The rate and periodicity of the emission of the sex pheromone [(Z)-11-hexadecenal] from the pheromone glands of individual female artichoke plume moths, Platyptilia carduidactyla, were quantified. The mean rate of volatilization of (Z)-11-hexadecenal from the glands of the moths peaked at 1.52 ± 0.41 (SE) ng/min during the scotophase, and was at low levels during the entire photophase. This periodicity in emission rate paralleled the behavioral periodicity of calling by females, indicating a close coordination of the biochemical and behavioral aspects of pheromone release. The highest recorded emission rate from a female P. carduidactyla was 5.1 ng/min. No other pheromone-like compounds were detected in these pheromone collections.

A high-efficiency collection device for sex pheromones volatized from forcibly extruded female glands is described. Filtered nitrogen gas is the carrier and glass wool the adsorbent. Small quantities of distilled carbon disulfide are used to rinse the glass wool. Recovery efficiency of synthetic compounds was usually 90-100%, and a mean of 2.4 ± 0.65 SD ng/min of (Z)-7-dodecenyl acetate was recovered in emissions from individualTrichoplusia ni (Hubner) glands.

The airborne volatiles emitted from individual female Heliothis zea (Boddie) pheromone glands were collected by adsorption onto glass wool, analyzed, and quantified on an SP-2330 capillary GLC column. All of the compounds previously reported from gland washes, 16:Ald, Z7-16:Ald, Z9-16:Ald and Z11-16:Ald, were found in the volatile emissions. The forcibly extruded female H. zea pheromone glands exhibited a periodicity of pheromone release: maximal pheromone emission occurred between 1 and 2 h and the minimal pheromone emission between 5 and 21 h after the onset of scotophase.

After an extensive examination of the release rates and blend ratios of pheromonal components emitted by field-collected femalePectinophora gossypiella (Saunders), we find no evidence of resistance to pheromones applied to cotton fields to disrupt mating. Females from fields with 3-5 years of exposure to disruptant pheromones as well as those from fields with only minimal exposure to disruptant pheromones emitted (Z,Z)-7,11-hexadecadienyl acetate at a rate of ca. 0.1 ng/min and (Z,E)7,11-hexadecadienyl acetate at ca. 0.06 ng/min. The ratio of pheromonal components was much less variable than the measured emission rate and was centered about a 61:39Z, Z to Z,E ratio. In contrast to the blend ratio emitted by females, the composition of the pheromonal blend used in monitoring populations and disrupting mating is centered about 50:50 Z,Z to Z.E. In general there was a remarkable consistency in the release rate and blend ratio among populations of females throughout southern California and those from a laboratory colony. It would appear that, although resistance to theP. gossypiella pheromone is still a very real possibility when it is used heavily in pest management as a mating disruptant, there are current agricultural practices and conditions which would hinder its development.