ETHANOL TOLERANCE AND VARIATION AT THE ALCOHOL-DEHYDROGENASE (ADH) LOCUS OF DROSOPHILA-MAURITIANA

Drosophila mauritiana larvae are tolerant to ethanol as a supplementar y nutritional resource at low concentrations. Higher levels of ethanol (5 per cent) in the food adversely affect larval behaviour causing re duced rates of locomotion and feeding which are associated with low la rva-to-adult survival. Two codominant autosomal alleles Adh(S) and Adh (F) controlling variant electromorphs of alcohol dehydrogenase are ind istinguishable in their effects on ethanol tolerance in this species. A comparison of larval behaviours shows that D. mauritiana has a lower ethanol tolerance than either of its sibling species D. melanogaster and D. simulans.