Wolbachia, a new bacterial agent causing sex-ratio bias in the two-spot ladybird Adalia bipunctata L.

Some of the male-killing lines of the two-spot ladybird Adalia bipunctata L. isolated from the populations of Moscow and Tomsk and having a female-biased sex ratio were found to be infected with a bacterium of the genus Wolbachia. This fact is the first demonstration of the ability of Wolbachia to kill males of a host insect. The coexistence of females infected with different male-killing bacteria was recorded in the population of Moscow.