Brain Factor Control of Sex Pheromone Production in the Female Corn Earworm Moth

Isolated abdomen and pheromone gland bioassays were utilized to determine the physiological action of the pheromone-biosynthesis-activating neuropeptide (PBAN) in the corn earworm moth Helicoverpa (= Heliothis) zea. An isolated pheromone gland bioassay showed that synthetic PBAN was active at 0.02 pmol, with maximal activity occurring at 0.5 pmol and 60 min of incubation. Second-messenger studies demonstrated that extracellular Ca2+ is necessary for PBAN activity on isolated pheromone glands. The Ca2+ ionophore A23187 stimulated pheromone biosynthesis alone, whereas the Ca2+ channel blockers La3' and Mn2+ inhibited PBAN activity. However, the organic Ca2+ channel blockers verapamil and nifedipine did not inhibit PBAN activity. Both forskolin and two cAMP analogues stimulated pheromone biosynthesis in the absence of extracellular Ca2+, indicating that Ca2+ may activate an adenylate cyclase. The biogenic amine octopamine did not elicit pheromone production in isolated gland or abdomen bioassays or when in ected into intact female moths. Removal of the ventral nerve chord, including the terminal abdominal ganglia in isolated abdomens, did not affect PBAN stimulation of pheromone production. Similar levels of stimulation were found when isolated abdomens were treated with PBAN in scotophase or photophase.Sex pheromone titers in most moths, including the corn earworm moth Helicoverpa (= Heliothis) zea, fluctuate diurnally with little or no pheromone present during the day and with peak pheromone titers occurring during midscotophase (1). This fluctuation is caused by the release and/or degradation of existing pheromone and the biosynthesis of new pheromone at precise times of the photoperiod. The biosynthesis of pheromone in H. zea is regulated by a peptide produced in the subesophageal ganglion (SEG) portion of the brain complex of female moths (2). This peptide, termed pheromone-biosynthesis-activating neuropeptide (PBAN), has been isolated and sequenced from brains of H. zea (3).Two other pheromonotropic peptides, each with about 80%o sequence identity with H. zea PBAN, have been isolated from the brains of the silkworm, Bombyx mori (4, 5). These peptides have been synthesized and the synthetic peptides retain biological activity, with cross-reactivity occurring in other species of moths (3, 4, 6, 7). These reports and others indicate that a variety of moths utilize PBAN or PBAN-like peptides in controlling pheromone biosynthesis.Although PBAN or PBAN-like activity has been identified in several different moth species, the physiological mode of action of PBAN has not been determined conclusively for any one species. In fact, there are two apparently conflicting hypotheses on how PBAN activates pheromone biosynthesis, and both are based on studies utilizing Heliothis moths as experimental animals. One hypothesis suggests that PBAN is synthesized in the SEG, transported to the corpora cardiaca, and then released into the hemolymph, where it can act on the pheromone gland to induce pheromone biosynthesis (8)....

mentioning

confidence: 99%

Stimulation of pheromone biosynthesis in the moth Helicoverpa zea: action of a brain hormone on pheromone glands involves Ca2+ and cAMP as second messengers.

Jurenka

Jacquin

Roelofs

1991

“…Female moths emit pheromone only when they call, a behavior that requires input from the brain or other higher nervous centers (1)(2)(3)(4). Production of pheromone, on the other hand, is under neuroendocrine control by a peptide localized in the subesophageal ganglion portion of the brain complex (5)(6)(7).…”

mentioning

confidence: 99%

Regulation of pheromone biosynthesis by a brain hormone in two moth species

et al. 1989

100

Experiments were performed to characterize the action of a brain hormone on pheromone biosynthesis in female redbanded leafroller and cabbage looper moths. Results showed that the two species differed in their respective control mechanisms. In the cabbage looper, pheromone titer from decapitated females that received either saline or brain extract injections was not significantly different from control females, suggesting that pheromone biosynthesis was not dependent on the presence of the brain hormone. In contrast, with redbanded leafroller females, studies using radiolabeled acetate incorporation as well as incorporation of-deuterium-labeled hexadecanoic acid showed that. (i) the brain hormone was required for pheromone biosynthesis, (ii) the brain hormone regulated pheromone biosynthesis by activating synthesis of octadecanoyl and hexadecanoyl intermediates, and (ii) the brain hormone did not control other enzymes in the pathway. Regulation of fatty acid synthetase was unlikely since assays of the enzyme from decapitated and normal females showed no differences in the amount or distribution ofthe 18-and 16-carbon acyl end products. These results in conjunction with those from organ cultures of the pheromone gland suggest that the brain hormone'acts by increasing the substrate supply for fatty acid synthesis.Recent research in moths has greatly advanced our understanding of the endogenous control mechanisms responsible for sex pheromone production and release. Female moths emit pheromone only when they call, a behavior that requires input from the brain or other higher nervous centers (1-4). Production of pheromone, on the other hand, is under neuroendocrine control by a peptide localized in the subesophageal ganglion portion of the brain complex (5-7).Several lines of evidence support the existence of a brain hormone that controls pheromone production. After neckligation or decapitation, females exhibited a decrease in pheromone titer (5, 6). A subsequent increase in titer was induced by injection of brain extract. Since hemolymph showed pheromonotropic activity only during periods when a female was producing pheromone, it was concluded that control of pheromone production was mediated by release of the brain hormone into the hemolymph at specific times of the day (5). The presence of functionally similar pheromonotropic factors in several families of moths has been demonstrated (5, 7) as well as from brains of insects from other orders-e.g., a cockroach, Periplaneta americana, and a cricket, Gryllus bimaculatus (L.S. and W.L.R., unpublished results).The biosynthetic pathways ofpheromone production for the two species examined in the present study, the redbanded leafroller moth (RBLR), Argyrotaenia velutinana, and the cabbage looper moth (CL), Trichoplusia ni, are depicted in

“…PBAN's function in the male has been unresolved since its discovery over two decades ago (22,23), however PBAN-like activity is widespread among Lepidoptera as well as other invertebrate species which have peptides with the common FXPRLamide C-terminal motif (24,25) and not all insects regulate pheromone biosynthesis using this peptide (26). PBAN-like peptides, found in other insects, have been shown to have other functions (27)(28)(29)(30)(31)(32) indicating the ubiquitous and pleiotropic nature of this peptide family.…”

mentioning

confidence: 99%

Gene-silencing reveals the functional significance of pheromone biosynthesis activating neuropeptide receptor (PBAN-R) in a male moth

Bober

Rafaeli

2010

The role of pheromone biosynthesis activating neuropeptide (PBAN) in the regulation of pheromone biosynthesis of several female moth species is well elucidated, but its role in the males has been a mystery for over two decades since its discovery from both male and female central nervous systems. In previous studies we have identified the presence of the gene transcript for the PBAN-G-protein coupled receptor (PBAN-R) in Helicoverpa armigera male hair-pencil-aedaegus complexes (male complexes), a tissue structurally homologous to the female pheromone gland. Moreover, we showed that this transcript is up-regulated during pupal-adult development, analogous to its regulation in the female pheromone-glands, thereby indicating a likely functional gene. Here we argue in favor of PBAN's role in regulating the free fatty-acid components (myristic, palmitic, stearic, and oleic acids) and alcohol components (hexadecanol, cis-11 hexadecanol, and octadecanol) in male complexes. We demonstrate the diel periodicity in levels of male components, with peak titers occurring during the 7th-9th h in the scotophase, coincident with female pheromone production. In addition, we show significant stimulation of component levels by synthetic HezPBAN. Furthermore, we confirm PBAN's function in this tissue through knockdown of the PBAN-R gene using RNAi-mediated gene-silencing. Injections of PBAN-R dsRNA into the male hemocoel significantly inhibited levels of the various male components by 58%-74%. In conclusion, through gain and loss of function we revealed the functionality of the PBAN-R and the key components that are up-regulated by PBAN.aedaegus | hair-pencils | Helicoverpa armigera | male-produced components R eproductive behavior involves the integration of physiological and behavioral events that synchronize male and female encounters. Receptivity in female moths is broadcasted by the release of a blend of volatile sex-pheromones during specific times of the photoperiod when they assume typical calling behaviors.