Male-killing bacteria in insects: Mechanisms, incidence, and implications

Bacteria that are vertically transmitted through female hosts and kill male hosts that inherit them were first recorded in insects during the 1950s. R ecent studies have shown these "male-killers" to be diverse and have led to a reappraisal of the biology of many groups of bacteria. Rickettsia, for i nstance, have been regarded as human pathogens transmitted by arthropods. T he finding of a male-killing Rickettsia obligately associated with an insec t suggests that the genus' members may be primarily associated with arthrop ods and are only sometimes pathogens of vertebrates. We examined both how k illing of male hosts affects the dynamics of inherited bacteria and how mal e-killing bacteria affect their host populations. Finally, we assessed the potential use of these microorganisms in the control of insect populations.