Molecular analysis of the desaturase2 (desat2) gene responsible for female cuticular hydrocarbon synthesis, revealed that all tested Israeli populations of Drosophila melanogaster belong to the 'Low' type (low ratio of 5,9-/7,11-heptacosadiene) with a 16 bp deletion in the promoter region. Additional deletion leading to the appearance of the stop-codon TGA was found in exon 1 in populations inhabiting opposite slopes at Nahal Oren canyon. Mating experiments between carriers of various desat2 alleles estimated the putative effect of desat2 status on courtship behaviour. The allele with an additional deletion in exon 1 seems to play some role in mating success, which is associated with shorter courtship latency and courtship duration. The appearance and maintenance of this mutant allele in populations inhabiting Nahal Oren canyon may reflect flies' adaptation to peculiar microscale climatic conditions and may be associated with incipient sympatric differentiation.