Submitted to: Peptides
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: October 19, 2001
Publication Date: June 1, 2002
Citation: TEAL, P.E., NACHMAN, R.J. A BROMINATED-FLUORENE INSECT NEUROPEPTIDE ANALOG EXHIBITS PYROKININ/PBAN-SPECIFIC TOXICITY FOR ADULT FEMALES OF THE tobacco BUDWORM MOTH. PEPTIDES. 23:801-806. 2002. Interpretive Summary: Insects, like all other animals, use chemicals called neuropeptides to control growth, development and reproduction. These neuropeptides, produced by the brain, are attractive targets for development of novel methods of insect pest control. However, neuropeptides do not penetrate the surface of the insect. Therefore, development of new strategies for pest control based on these neuropeptides requires the development of a delivery system that allows them 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 U. S. livestock Insect Laboratory, College Station, Texas have synthesized and modified an insect neuropeptide so that it penetrates the insect cuticle and stimulates production of pheromone for prolonged periods. This analog also has a toxic effect on adult female tobacco budworm moths that are serious pests of cotton in the United States. This analog appears to work by binding permanently with receptor sites for the natural peptide, thus causing death. The results provide important information for development of new strategies for pest control based on the use of insect neuropeptides because analogs can be designed to penetrate the cuticle of specific pest insects cause death.
Technical Abstract: An analog of the insect pyrokinin/PBAN class of neuropeptides, which features a 2-Amino7-bromofluorene attached to the carboxy-terminal bioactive core of the insect pyrokinin/PBAN class of neuropeptides (Phe-Thr-Pro-Arg-Leu-NH2), via a succinnic acid linker, was tested in adult H. virescens moths. This analog was found to induce pheromone production when injected into or applied topically to moths. Topical application of as much as 1nmol of the analog to moths induced production of significant amounts of pheromone for only 1-2 h where as injection of 500 pmol induced pheromone production for up to 20 h. All insects died within 24 h after injection of 500 pmol of the analog. Mortality studies indicated that the LD50 for the analog was 0.7 pmol. A non-pyrokinin/PBAN peptide analog formed by attachment of 2-Amino-7-bromofluorene to Ala-Ala-Arg-Ala-Ala-NH2 (via the succinnic acid linker) did not induce mortality when injected at 1nmol. Similarly no mortality was found when up to 2 nmol of an analog containing a non-brominated fluorene ring, formed by attachment of 9-fluoreneacetic acid to Phe-Thr-Pro-Arg-Leu-NH2, was injected into moths. The data indicated that both the bromine and active core of the pyrokinin neuropeptides (Phe-Thr-Pro-Arg-Leu-NH2) were critical for a specific toxic action and suggested that the brominated analog poisoned the moths by interacting with pyrokinin receptors.