ETHANOL EFFECT ON DEVELOPMENT TIME IN DROSOPHILA-MELANOGASTER - GEOGRAPHICAL VARIABILITY

The effect of ethanol on pre-imaginal development time was studied in natural populations of Drosophila melanogaster from France and Africa. It was observed that the higher the concentration of ethanol in the larval medium, the more important was the delay in pre-imago development. For each population, the regression coefficient ((b)TD) of the development time on the ethanol concentration was computed. This coefficient was negatively correlated with the latitude of the trapping sites of the populations. Such was also the case with the ethanol tolerance of these populations. Thus, the better adaptation of the palearctic populations to an ethylic environment arises not only from a better egg-to-adult survival, but also from a lesser sensitivity to the delay-effect of ethanol on pre-imaginal development. Although a correlation between the (b)TD coefficient and the frequency of the Adh(F) allele was observed, it was not possible to determine whether these was a causal relationship between the 2 traits or whether this was due to a latitude factor.