Oviposition site preference in four species of Drosophila.

Oviposition site preference which is an important aspect of nonsexual behaviour of adult females was studied in four species of Drosophila, viz. D. ananassae, D. bipectinata, D. malerkotliana and D. biarmipes. The number of eggs laid by females in food vials was counted for 20 days. In each species, eggs were counted in both central and peripheral areas of culture medium. Eggs were also separated into two groups: deposited on the surface of food medium and inserted into the surface of culture medium. Greater proportion of eggs was oviposited in peripheral area of food medium and were inserted into the surface of the medium by females of all the four species. However, there are interspecies variations with respect to oviposition site preference. Further, these species show variation with respect to total fecundity. D. ananassae lays maximum number of eggs whereas D. biarmipes shows lowest rate of fecundity.