Interference between "Sex-Ratio" Agents of Drosophila willistoni and Drosophila nebulosa

Abstract
Interference between two "sex-ratio" agents—that is, treponemalike spirochetes—of different origin, one from Drosophila willistoni and the other from D. nebulosa, was demonstrated by experiments in vivo and in vitro. When the two sex-ratio agents were combined in females of the Oregon-R strain of D. melanogaster, expression of the sex-ratio condition was temporarily interrupted. Several lines of evidence indicate that a substance produced by the sex-ratio agent of D. nebulosa may kill or incapacitate the sex-ratio agent of D. willistoni.