High-prevalence male-killing Wolbachia in the butterfly Acraea encedana

Inherited bacteria which kill males during early development are widely dis tributed throughout the insects, but have been little studied outside of a single family of beetles, the Coccinellidae. We have investigated a male-ki lling bacterium discovered in the butterfly Acraea encedana. This bacterium belongs to the genus Wolbachia and is identical in wsp gene sequence to a male-killer in the closely related butterfly A. encedon, suggesting that it has either recently moved between host species or was inherited from a com mon ancestor of the butterflies. The prevalence of Wolbachia is remarkably high, 95% of females are infected and only 6% of wild caught butterflies ar e male. Measurements of the vertical transmission efficiency were used to c alculate that this high prevalence is the result of infected females produc ing at least 1.79 times the number of surviving daughters as uninfected fem ales (lower confidence limit is 1.25).