Demonstration of an ecdysis-triggering compound in the epitracheal gland of the cotton bollworm, Helicoverpa armigera (Hubner) (Lepidoptera : Noctuidae)

The recent report of an ecdysis-triggering hormone (ETH) in the tobacco hor nworm Manduca sexta and several other Lepidoptera prompted the search for t he homologous hormone in the pest noctuid, Helicoverpa armigera. In M. sext a, ETH is produced in a large cell that forms part of a three-cell epitrach eal gland complex found near each of the the larval and pupal spiracles. Th e homologous glands were found in H. armigera and an ecdysis-triggering fun ction of the gland contents was confirmed by the induction of premature ecd ysis after injection of a crude gland extract into pupae.