Alcohol dehydrogenase allele frequencies in Bactrocera oleae (Dipt., Tephritidae): effect of ethanol addition in larval diet

: The effect of ethanol in larval medium on Bactrocera oleae larvae was examined at four concentrations. Ethanol exerted a differential effect on the three alcohol dehydrogenase allele frequencies. While originally being at equilibrium under laboratory conditions, after three generations of larval development in a diet containing ethanol at 1% concentration, Adh‐F allele frequency increased, that of Adh‐I dropped significantly and the frequency of Adh‐S remained unaltered. Adh‐S allele seems to be adapted in nature where only minor quantities of alcohol are present in the insects’ natural host, while Adh‐I is best adapted in the alcohol‐free laboratory culture medium. The frequency of Adh‐F allele remains unaltered when feral populations are introduced in the laboratory.