Infection by Wolbachia correlates with social structure in the ant Temnothorax longispinosus

Many insects are infected by Wolbachia, an intracellular bacterium transmitted via the cytoplasm in the eggs. In social insects, Wolbachia may affect female development, social structure and productivity of the colony, by either manipulation to promote female egg laying or as a byproduct of the infection. We screened colonies for Wolbachia infection while also observing the queen number, queen size, and the size and number of new queens produced in nests of Temnothorax longispinosus, a cavity nesting forest ant with polymorphic queens. Queen number per nest in a given forest patch negatively correlated with the prevalence of Wolbachia infection in that patch. Infection with Wolbachia also correlated significantly with the number of large new queens produced but did not affect small queen production. The potential for Wolbachia to influence queen size and caste determination in T. longispinosus populations suggests the parasites could play an intriguing role in social evolution and reproductive behavior.