Submitted to: Sociobiology
Publication Type: Peer reviewed journal
Publication Acceptance Date: 5/17/2009
Publication Date: 12/30/2009
Citation: Troyer, E.J., Dewrstine, N.T., Showalter, D.N., Jang, E.B., Siderhurst, M.S. 2009. Field Studies of Wasmannia auropunctata Alkylpyrazines: Towards Management Applications. Sociobiology. 54:955-971 2009 Interpretive Summary: The little fire ant is an emerging pest of agriculture in Hawaii and the US mainland. It’s sting are uncomfortable and in large number result in severe reactions. The alarm pheromone of the little fire ant was re-analyzed and found to be identified incorrectly. We used analytical instruments to identify the correct structure of the alarm pheromone and showed that this pheromone had much better biological activity than the previously identified compound. This compound may be useful in delimiting the spread of this invasive pest.
Technical Abstract: Field bioassays with Wasmannia auropunctata (Roger) show that the alarm pheromone components 2,5-dimethyl-3-(2-methylbutyl)pyrazine and 3-methyl-2-(2-methylbutyl)pyrazine both attract and arrest ants in a natural environment. Comparisons between lures containing 2,5-dimethyl- 3-(2-methylbutyl)pyrazine and 3-methyl-2-(2-methylbutyl)pyrazine singly and in blends (10:1 and 100:1) based on W. auropunctata extracts, failed to show differences in the time required to attract a given number of ants. This indicates a lack of synergistic effects between the compounds under these test conditions. A dose response assay with 2,5-dimethyl-3-(2-methylbutyl)pyrazine showed maximal ant response to a 1 mg pheromone lure, a dose which remained attractive for 8 days under field conditions. Several of the field experiments included peanut butter baits, a lure currently used for detection. However, ant counts at peanut butter baits were not greater than at controls suggesting that peanut butter does not produce volatiles that attract ants. With the aim of developing management applications, a series of bioassays were conducted with 2,5-dimethyl-3-(2-methylbutyl)pyrazine in combination with food baits. A separate assay was conducted with Tanglefoot, a sticky catch material. In feeding bioassays, the alarm pheromone decreased consumption of peanut butter and solutions of protein and sugar. Tanglefoot squares failed to catch W. auropunctata with any of the lures tested. The field responses of W. auropunctata to alarm pheromone lures show a mixed potential for control applications. While the strong attraction and longevity of lures is promising, the inability to increase bait consumption or capture ants withTanglefoot presents obstacles to using these alarm pheromone components for ant management.