Genetics of food preference inDrosophila sechellia

Abstract

To reveal the genetic mechanism of host selection in a monophagous fruit flyDrosophila sechellia, olfactory responses and oviposition preferences of this species were compared with those of closely related polyphagous species,D. simulans andD. melanogaster. Adult flies ofD. sechellia were strongly attracted to the ripe fruit ofMorinda citrifolia which is known to be the sole breeding site of this species. They were also attracted to the odor ofn-caproic acid which is contained in the ripe fruit ofM. citrifolia and is presumably responsible for the characteristic odor of the fruit. In contrast,D. simulans andD. melanogaster showed a strong repulsion ton-caproic acid. In parallel with the olfactory responses,D. sechellia females laid eggs preferentially on a medium containingn-caproic acid, to which the other two species showed an aversion. Genetic analyses using the hybrid progeny betweenD. sechellia andD. simulans suggested that the species differences in these behaviors are controlled by gene(s) located on the second chromosome.