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Department of Entomology

ISU Entomology / Paul A. Dahm Memorial Seminar: Chemical Coding of Innate Behavioral Sequences in Insects

Paul A. Dahm Memorial Seminar: Chemical Coding of Innate Behavioral Sequences in Insects

Michael E. Adams, Department of Entomology, University of California, Riverside, CA
Abstract: Molting and ecdysis are among the most distinctive and characteristic features of arthropod physiology and are vital for growth and metamorphosis from juvenile to the winged, reproductive adult. The programming of these events is under the control of steroid and peptide hormones. We are interested in how hormones initiate and schedule the ecdysis sequence, a series of innate behaviors that allows escape from the old cuticle to terminate the molt. These behaviors are initiated and scheduled by ecdysis triggering hormones (ETHs) that regulate neuropeptide signaling cascades in the central nervous system (CNS). Ecdysteroids signal onset of the molt and program expression of genes encoding ecdysis signaling molecules. In moths (Bombyx mori, Manduca sexta) and flies (Drosophila), we identified primary neuronal targets of ETH in the CNS by expression of ETH receptor (ETHR) transcripts and monitored activities of ETHR neurons by electrophysiology and calcium imaging. ETHRs are expressed predominantly in “peptidergic ensembles”, groups of central neurons that release FMRFamides, eclosion hormone, kinins, CCAP, MIPs, and bursicon into the CNS to schedule activation of central pattern generators that drive pre-ecdysis, ecdysis, and post-ecdysis. We are examining the roles played by these neurons in behavioral scheduling using genetics and physiological manipulations. Our findings offer insights into how neural substrates for behaviors are assembled and executed and provide new opportunities for insect control by targeting physiological processes unique to insects.