Submitted to: Insect Molecular Biology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/5/2008
Publication Date: 3/13/2009
Citation: Choi, M.Y., Vander Meer, R.K. 2009. Identification of a new member of PBAN family of neuropeptides from the fire ant, Solenopsis invicta. Insect Molecular Biology. 18(2):161-169.
Interpretive Summary: Imported fire ants cause over 6 billion dollars in annual control and damage costs in the United States and have spread to many other countries. Novel biologically-based or environment friendly methods of controlling these pest ants are needed to reduce our dependence on pesticides. Insect hormones play many critical roles during insect development and as adults. More than 90% of insect hormones are neuropeptides. Identifying and understanding how insect neuropeptides work in the fire ant could lead to new control methods. Scientists at the Center for Medical, Agricultural and Veterinary Entomology, USDA, ARS, Gainesville, FL have established for the first time the identification and characterization of the fire ant PBAN (pheromone biosynthesis activating neuropeptide: PBAN) gene. The gene has been submitted into GenBank with accession number: FJ223176. The synthetic PBAN and the other three additional peptides from the fire ant PBAN cDNA were confirmed to stimulate pheromone production using a moth model. In addition, a neuropeptide phylogenetic tree, based on insect PBAN genes thus far identified is consistent with insect taxonomical classification. This is also the first attempt to compare peptide hormone diversity and taxonomic evolution in insects. Little is known about the regulation of pheromone production and release, nor whether protein hormones, especially neuropeptides, are involved in key physiological and endocrinal processes during development. This is the initial step in developing novel, non-insecticide methods for fire ant control based on the interference of normal neuropeptide hormone functions.
Technical Abstract: Neuropeptide hormones produced by neurosecretory cells in the central or peripheral nervous systems regulate various physiological and behavioral events during insect development and reproduction. Pyrokinin/Pheromone Biosynthesis Activating Neuropeptide (PBAN) is a major neuropeptide family, characterized by a 5-amino-acid C-terminal sequence, FXPRLamide. The pentapeptide is essential to various physiological functions including, pheromone biosynthesis, muscle contraction, diapause induction or termination, melanization, and puparium formation in different insect species. In the present study, we report a new PBAN peptide from the red imported fire ant, Solenopsis invicta, Soi-PBAN, composed of 26-AA (GSGEDLSYGDAYEVDEDDHPLFVPRL). Three additional peptides were deduced from Soi-PBAN cDNA: 15-AA (TSQDIASGMWFGPRL), 8-AA (QPQFTPRL) and 9-AA (LPWIPSPRL), that correspond to Diapause Hormone (DH), ß-Neuropeptide (NP), and '-NP, which are found in many lepidopteran moths. Five peptides, DH, a, ß, ' NPs, and PBAN are encoded from PBAN genes of lepidopteran moths, but in the fire ant the a-NP is missing. Each of the four peptides from the fire ant Soi-PBAN cDNA showed significant pheromonotropic activity in a moth model, indicating that these peptides are cross-reactive. Soi-ß-NP induced the highest amount of pheromone production of the four peptides evaluated. The Soi-DH homologue had the lowest pheromonotropic activity, but was still significantly greater than control values. When the deduced amino acid sequences (entire ORF domains) from Soi-PBAN cDNA were compared with other known sequences, the fire ant was most similar to the honey bee, but phylogenetically distant from moth and beetle species. Soi-PBAN (26-AA) unlike the other three peptides shows a low degree of homology with honeybee PBAN (33-AA) even though they both belong in the Hymenoptera group. Based on the amino acid sequences encoded from insect PBAN genes identified to date, neuropeptide diversity is consistent with the taxonomic or phylogenetic classification of Insecta.