Bombyxin: an insect neurohormone targets the ovaries in Lepidoptera

Bombyxin, an insect hormone structurally related to insulin, was chemically synthesized and defined radioactively labeled probes were generated in order to detect and characterize bombyxin receptors in insect tissue. In all species tested, Bombyx mori (silkmoth), Samia cynthia ricini (Ailanthus moth). Manduca sexta (tobacco hornworm) and Spodoptera frugiperda (fall armyworm), bombyxin receptors were found in ovaries. A radioactive photolabeled bombyxin analog was crosslinked to the potential bombyxin receptor and the hormone-receptor complex identified by SDS PAGE. The bombyxin-receptor has an apparent molecular mass of about 300 kDa which after reduction forms a binding subunit of 90 to 110 kDa. The presence of bombyxin-receptors on ovaries suggests a function of this hormone in reproduction.