Abstract
Drosophila melanogaster males carrying the fruitless mutation have been studied in their interactions with males and females. Mutant males—expressing a single recessive factor on the third chromosome—court mutant or wild-type males about 7 times more frequently than wild-type males court each other. Courtship by a fruitless male of a wild-type male is sustained and takes up an amount of time almost 100 times greater than the courtship interactions recorded between two normal males. While the mutant males do court females in a sustained manner, they attempt to copulate in less than 1% of the trials, never do copulate, and are thus behaviorally sterile. Fruitless males, when interacting with other males, are deficient in their degree of rejection responses, but this defect is not sufficient to explain the abnormal male-male interactions. The mutants stimulate wild-type males to court them with a frequency which is about 5 times higher than that observed between normal males. Fruitless males can stimulate other males to court them even when the former have been etherized or cut into pieces.