Egg-laying preference for ethanol involving learning has adaptive significance in Drosophila melanogaster

To study the influence of negative or positive experience of the ingestion of ethanol in female Drosophila with the fast form of the Adh gene on the acceptance of a medium containing this substance as site for egg laying, flies raised on a medium without alcohol were kept (1) on a regular medium, (2) on a medium supplemented with ethanol, (3) on a medium supplemented with 4-methylpyrazxole (4-MP, an inhibitor of the enzyme ADH), and (4) on a medium containing both ethanol and this inhibitor.