Mating propensity in Drosophila bipectinata under different sex-ratios andchoice situations

To test the effect of sepia eye colour mutation on mating activity in D, bi pectinata, experiments were conducted by using mutant and wild-type stocks and employing multiple-, female-, male- and no-choice techniques, Mating su ccess in different experiments was observed in Elens-Wattiaux mating chambe r for one hour. The values of isolation estimate;in different experiments a re close to one and the difference. between the numbers of homogamic and he terogamic matings is not significant, indicating random mating between wild -type and mutant flies, The comparison of sexual activity of two types of f lies clearly indicates that wild-type males are more successful in mating t han mutant males, However, there is no difference in the sexual activity of two types of females. Thus sepia eye colour mutation diminishes the sexual activity of males in D, bipectinata which provides evidence for sexual sel ection. The results of mating propensity tests obtained in the experiments employing multiple-, female- and male-choice techniques are similar showing significant difference in the number of matings of the two types of males. However, the difference in the number of matings of sepia mutant and wild- type males is not significant in no-choice experiments, Thus,;sexual activi ty is influenced by different choice situations, However, sex-ratio has no effect on the mating success in D, bipectinata.