Receptivity Terminating Factor in Heliothis Zea and its Interaction with PBAN

Abstract

Mating in most species of Lepidoptera is mediated by the production and release of sex pheromones. In the corn earworm, Heliothis zea, virgin females, while releasing the pheromone, are receptive to approaching males. After mating there is a switch from the virgin to the mated behavior expressed by termination of pheromone production and loss of receptivity to further mating (Raina et al., 1986; Raina, 1989). This switch is caused by a putative receptivity terminating factor (RTF), transferred by the male to the female at the time of mating (Raina, 1989). The testes or the sperm do not contribute to the presence or transfer of this factor, and it was postulated that the source of RTF is the male accessory glands (AG). The material, after transfer along with the spermatophore, is released into the hemolymph and, in an as yet unknown way, blocks the release and/or action of the pheromone biosynthesis activating neuropeptide (PBAN). Similar observations have been reported in the house fly, Musca domestica, by Leopold et al. (1971), who noted that radiolabelled male ejaculatory duct material, after transfer to the female, was released into the hemolymph and carried to the head region. The factor caused termination of receptivity in the female house flies. Among the Lepidoptera, Riddiford and Ashenhurst (1973) speculated that receptivity in Hyalophora cecropia was terminated by the release of a substance from either the spermatheca or bursa of a mated female and its passage via hemolymph to a hypothetical neural center in the brain.