Submitted to: Proceedings of the National Academy of Sciences (PNAS)
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/23/1996
Publication Date: N/A
Interpretive Summary: Over the past decade there has been much emphasis on the study of a class of insect hormones called neuropeptides. Neuropeptides regulate virtually all aspects of insect physiology and are therefore attractive targets for development of novel methods of insect pest control. However, neuropeptides do not penetrate the surface of the insect when applied topically. Therefore, development of new strategies for pest control base on these neuropeptides requires the development of a delivery system that allows these hormones to enter the body after being applied to the surface of the insect. Scientists at the Center for Medical, Agricultural and Veterinary Entomology, USDA, ARS, Gainesville, Florida and Food Animal Protection Research Laboratory, College Station, Texas have successfully synthesized a modified insect neuropeptide that penetrates the insect cuticle and stimulates sex pheromone production. This is the first time that a mimic of an insect neuropeptide has been shown to penetrate the insect cuticle and maintain biological activity. The results provide important information for development of new strategies for pest control based on the use of insect neuropeptides. Additionally, the results provide important information that could be used to design neuropeptides that are important to physiological functions of other organisms, including livestock and humans.
Technical Abstract: An amphiphyllic analog of Locusta myotropin II (Lom-MT-II), Glu-Gly-Asp-Phe-Thr-Pro-Arg-Leu-amide, was synthesized by addition of 6-phenylhexanoic acid linked through alanine to the amine terminus. This pseudopeptide, [6-Pha-Ala]Lom-MT-II, was found to have pheromonotropic activity equivalent to pheromone biosynthesis activating neuropeptide when injected into females of Heliothis virescens. Topical application of [6-Pha-Ala]Lom-MT-II or Hez-PBAN, dissolved in dimethyl sulfoxide, to the descaled abdomen of females induced production of pheromone, although more Hez-PBAN than [6-Pha-Ala]Lom-MT-II was required to obtain significant production of pheromone. Application of [6-Pha-Ala]Lom-MT-II, dissolved in water, to the abdomen induced production of pheromone but neither Hez-PBAN nor Lom-MT-II, dissolved in water stimulated production of significant amounts of pheromone. Dose and time response studies indicated that application of the amphiphilic mimetic in water induced pheromone production in as little as 15 minutes after application and that the effects were maintained for prolonged periods. These findings represent the first instance of an endogenous response induced by a pseudopeptide mimic of an insect neuropeptide when applied topically in water to the cuticular surface of an insect.