Motomichi DOI and Yuzuru OGUMA
Institute of Biological Scences, University of Tsukuba, Tsukuba,
Ibaraki 305, Japan
Drosophila ananassee and D. pallidosa are very close relatives. They can produce fertile hybrids in a laboratory condition, but they are sexually isolated each other in nature. Cuticular hydrocarbons of Drosophila are known as a signal to recognize their own species. Some of them have been identified as contact sex pheromones. (Z,Z)-5,27-tritriacontadiene has been shown a major sex pheromone component in D. pallidosa (Nemoto et al., 1994), and (Z,Z)-5,25-hentriacontadiene in D. ananassae (Doi et al., in preparation). Their hydrocarbon, or sex pheromone difference causes mate recognition by males and should be one of factors in sexual isolation between two spades. We analyzed the genetic basis of the sex pheromone production in females and perception in males.
Female cuticular hydrocarbon ponies are species-specfic: (Z,Z)-5,25-hentriacontadiene was the most abundant hydrocarbon in D. ananassae but little in D. pallidosa. D. pallidosa produced (Z,Z)-5,27-ttitriacontadiene as the most abundant one. Since F1 hybrid females from reciprocal crosses had a half of an amount of each of sex pheromones in both species, the production was judged to be semidominant. Backcross females analysis indicated that the third chromosome had a main effect of the sex pheromone production in D. ananassae and in D. pallidosa, respectively.
To understand the genetic basis of sex pheromone perception in males, we also analyzed courtship activity in F1 hybrids and backaoss males. F1 hybrid males from reciprocal crosses courted actively to both females and decoys with both sex pheromones. Chromosomal analysis showed that the sex pheromone perception was also controlled by the third chromosome of each of species. It is therefore concluded that the sex pheromone production in females and perception in males are controlled by the same chromosome in D. ananassae and D. pallidosa, respectively.