Parallel changes in enzyme activity and oviposition behavior in adults of Drosophila melanogaster submitted to alcohols, acetaldehyde or acetone

Abstract

Summary Two geographic populations of D. melanogaster, French and African, which differ in their frequencies at the Adh locus and their ethanol tolerance, were tested for their oviposition site preference, mortality and activities of two enzymes involved in alcohol metabolism. To investigate the oviposition choice towards ethanol, 2-propanol, acetaldehyde et acetone, females of the two populations of D. melanogaster were exposed to a choice situation opposing a medium free-alcohol to a medium supplemented with one of the tested compounds. We noticed that the avoidance of media containing one the two studied alcohols, acetaldehyde or acetone, increased during the experiment. The most repellent medium for ovipositing females was that supplemented with 2-propanol or acetone. Besides, the study of female mortality on attractant or repellent media revealed that the most repulsive media were also the most lethal. Moreover, the treatment with ethanol, 2-propanol, acetaldehyde or acetone led to a reduction in alcohol dehydrogenase (ADH) and aldehyde dehydrogenase (ALDH) activities. A strong inhibition of ADH occurs (78.57%) in females a few days after the treatement with the tested products. Compared to ADH activity, ALDH activity was less reduced (51.78%). We suggest that fly mortality and the fly's aversion to alcoholic media might be linked to the decline of ADH and ALDH activities. The toxic effects of the used compounds appear more clearly in African flies than in French ones.