MODIFIED THORACIC EPITHELIUM OF THE BAGWORM (LEPIDOPTERA, PSYCHIDAE) - SITE OF PHEROMONE PRODUCTION IN ADULT FEMALES

The site of synthesis and release of R-1-methylbutyl decanoate, the sex pheromone of the female bagworm, Thyridopteryx ephemeraeformis (Haworth), is unusual in Lepidoptera. Large amounts of pheromone were extracted and verified by gas chromatography from deciduous setae from ventral thoraces of calling females. Surface features of this part of the thorax, as revealed by scanning electron microscopy, include linear arrays of cuticular excrescences free of setal sockets. Within the excrescences of the ventral thorax and first abdominal segment are swollen cuboidal epithelial cells with enlarged nuclei. These large epithelial cells resemble cells responsible for pheromone synthesis in abdomens of other insects. This is the first report of the localization of a sex pheromone gland in modified epithelial cells of the adult thorax and first abdominal segment of a Nearctic lepidopteran species.