Submitted to: Journal of Chemical Ecology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: November 15, 1995
Publication Date: N/A
Interpretive Summary: Fruit flies are among the most important pests threatening the citrus industry in the United States. State and federal agencies in both the United States and Mexico spend a great deal of money and effort each year attempting to detect these pests in citrus- growing areas. Recent research to develop new attractants for fruit flies has indicated that ammonium acetate is a very effective attractant for various kinds of fruit flies and thus new attractants under development to detect fruit flies increasingly contain this chemical. Researchers suggest that the reason for the superior attractiveness of ammonium acetate is that it evolves acid acid in addition to ammonia, and that both chemicals contribute to the overall attractiveness. This work investigated whether acetic acid would also contribute to attraction of the Mexican fruit fly to an attractant called AMPu that also evolves ammonia. Only when flies were hungry for sugar did acetic acid increase the attractiveness of AMPu. Results call into question the value of ammonium acetate relative to other ammonium compounds as fruit fly attractants. This knowledge should lead to a better understanding of how fruit flies search for food by its smell and ultimately should enable more enlightened application of chemistry to development of attractants. Optimal trapping efficacies through usage of the best possible mixture of attractive chemicals is the best way to ensure early detection of pest fruit flies before their populations reach multimillion dollar eradication problems.
Technical Abstract: Ammonium acetate was more attractive than other ammonium salts to Mexican fruit flies (Anastrepha ludens) in an orchard test. We hypothesized that acetic acid enhanced the attractiveness of ammonia in the orchard test and that acetic acid may similarly enhance attractiveness of AMPu, an attractant consisting of a mixture of ammonium bicarbonate or ammonium carbonate, methylamine HCI and putrescine. In laboratory experiments, acetic acid was attractive to flies deprived of either yeast hydrolysate or both sugar and yeast hydrolysate but not to flies fed both sugar and yeast hydrolysate. AMPu/acetic acid combinations were more attractive than AMPu alone to flies deprived of both sugar and yeast hydrolysate but not to flies fed sugar, regardless of yeast hydrolysate deprivation status. Acetic acid is the first attractant that has become more attractive with both sugar and protein deprivation in studies with A. ludens. It is also the first that has enhanced the attractiveness of another attractant type. In orchard tests, yellow sticky panels baited with either AMPu or 17 mg of acetic acid were at least six times more attractive than unbaited panels. However, panels baited with both acetic acid (17-68 mg) and AMPu were less attractive than AMPu alone. These results differed from the laboratory data in which combinations were never less attractive than AMPu alone.