ADAPTATION TO ALCOHOLIC FERMENTATION IN DROSOPHILA - A PARALLEL SELECTION IMPOSED BY ENVIRONMENTAL ETHANOL AND ACETIC-ACID

Besides ethanol, acetic acid is produced in naturally fermenting sweet resources and is a significant environmental stress for fruit-breedin g Drosophila populations and species. Although not related to the pres ence of an active alcohol dehydrogenase, adult acetic acid tolerance w as found to correlate with ethanol tolerance when sensitive (Afrotropi cal) and resistant (European) natural populations of Drosophila melano gaster were compared. The same correlation was found when comparing va rious Drosophila species. Tolerance to acetic acid also correlated wit h the tolerance to longer aliphatic acids of three, four, or five carb ons but did not correlate with the tolerance to inorganic acids (i.e., hydrochloric and sulfuric acids). These observations suggest that ace tic acid is detoxified by the conversion of acetate into acetyl-CoA, a metabolic step also involved in ethanol detoxification. Future invest igations on the adaptation of Drosophila to fermenting resources shoul d consider selective effects of both ethanol and acetic acid.