Male-killing selfish cytoplasmic element causes sex-ratio distortion in Drosophila melanogaster

Sex ratio distortion induced by a male-killing agent has been found to affe ct Drosophila melanogaster. The trait was discovered accidentally in a coll ection of flies from markets in Campinas, Sao Paulo State, Brazil. Repeated crosses with Canton-S males (for 15 generations to date) and successful tr ansmission using the injection of macerates of sex ratio flies, have shown that the trait is inherited maternally, is cytoplasmic and is infectious. C rosses with strains marked with the visible mutation white and viability ex periments at pre-adult stages of development, indicate that the skewed sex ratio results from male mortality before hatching. Males do not transmit th e trait to their progeny.