Field studies of Wasmannia auropunctata alkylpyrazines: Towards management applications

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 pheromoneluresshowamixedpotential for control applications. While the strong attraction and longevity of lures is promising, the inability to increase bait consumption or capture ants with Tanglefoot presents obstacles to using these alarm pheromone components for ant management.