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Pheromone biosynthesis in females of Heliothis zea is regulated endogenously by a neuropeptide produced in the subesophageal ganglion. We have found that the ventral nerve cord must be intact for normal induction of pheromone biosynthesis and that pheromonotropic activity is associated with extracts of the abdominal nerve cord, but only during the period when pheromone is produced. We did not find evidence of pheromonotropic activity in hemolymph obtained from females that were producing pheromone. Extracts of the brain-subesophageal ganglion complex, which contain pheromone biosynthesis activating neuropeptide (PBAN), induced pheromone biosynthesis when applied to the terminal abdominal ganglion only if nerves from this ganglion to the pheromone gland were intact. Brain-subesophageal ganglion extracts did not induce biosynthesis when applied directly to the pheromone glands in vitro. From our results, we conclude that the target site of PBAN is not the pheromone gland but the terminal abdominal ganglion, and we hypothesize that the abdominal nerve cord transports PBAN to the terminal abdominal ganglion.Endogenous regulation of reproductive physiology and behavior associated with pheromone production and release in many insects results from the action of nervous, neuroendocrine, and/or endocrine stimulation (1-4). However, while the chemistry and biological effects of sex pheromones are understood more fully for moth species than for other groups of insects (5), the endogenous mechanisms that regulate the initiation and inhibition of pheromone biosynthesis by moths remain largely unexplored. Neural, neurohormonal, and hormonal regulators effectively control the periodicity of sexual signaling and are thus of prime importance for the reproductive success of moth species. Although these processes are tightly coordinated, no single neural, neuroendocrine, or endocrine factor regulates the complete system. In fact, there are conflicting reports (6-11) regarding the endogenous mechanisms that control even a single aspect of the pheromone communication system in moths: induction of pheromone biosynthesis.Studies on the corn earworm moth Heliothis zea (6-8) have firmly established that injection of extracts of the subesophageal ganglion induces pheromone biosynthesis. It was hypothesized that the neuropeptide responsible, pheromone biosynthesis activating neuropeptide (PBAN), was released from the corpora cardiaca, carried in the hemolymph, and acted directly on the cells of the pheromone gland (4, 6). However, gypsy moths, which also produce PBAN (6), do not require either the corpora allata or corpora cardiaca for production and release of the sex pheromone but do require that the ventral nerve cord be intact for production and release of normal amounts of pheromone (9-11). Thus, in this case neural rather than hormonal factors appear to be the main components regulating biosynthesis.These apparent discrepancies in the regulation of pheromone production caused us to investigate the mechanism by which PBAN ind...

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In memory of Christa L. Hoyt We have examined the effects of RH 5849, a lion-steroidal ecdysteroid mimic, on the growth and development of Plodia inferpuncteila. When R H 5849 was administered in the diet, larval growth was inhibited in a dose-dependent manner, while concentrations of 15 ppm and greater were highly toxic. However, the deleterious effects of RH 5849 could be prevented, except at very high concentrations of RH 5849, by the simultaneous administration of the juvenile hormone mimic methoprene. Larvae simultaneously treated with both hormone mimics continued to grow until they attained a size about three times normal. This growth was accompanied by at least one and sometimes two supernumerary molts, whereas, only an occasional supernumerary molt occurred in larvae treated with methoprene alone. In larvae undergoing supernumerary molts, wing imaginal discs produced a tanned pupal cuticle, but did not evaginate. When wing discs were cultured in vitro, RH 5849 stimulated evagination and chitin synthesis at concentrations of 10 and 1 pM, respectively. Likewise, RH 5849 stimulated GlcNAc uptake and inhibited cellular proliferation in IAL-PID2 cells at similar concentrations. These in vitro effects of RH 5849 also were produced by 20-hydroxyecdysone, but at lower concentrations. We conclude that RH 5849 exhibits molting hormone activity in vivo as well as in vitro. However, the toxicological effects in /? interpunctella result from action on feeding and growth, rather than molting. Thus, RH 5849 represents a new class of IGR, which will have impact on our understanding of endocrine regulation and open up new avenues for pest control.