Royal Society Publishing

Widespread occurrence of the microorganism Wolbachia in ants

T. Wenseleers, F. Ito, S. Van Borm, R. Huybrechts, F. Volckaert, J. Billen

Abstract

For more than 20 years, sex allocation in hymenopteran societies has been a major topic in insect sociobiology. A recurring idea was that relatedness asymmetries arising from their haplodiploid sex determination system would lead to various parent–offspring conflicts over optimal reproduction. A possible weakness of existing theory is that only interests of nuclear genes are properly accounted for. Yet, a diversity of maternally transmitted elements manipulate the reproduction of their host in many solitary arthropod groups. The bacterium Wolbachia is a striking example of such a selfish cytoplasmic element, with effects ranging from reproductive incompatibility between host strains, induction of parthenogenesis and feminization of males. This paper reports on a first PCR–based Wolbachia screening in ants. Out of 50 Indo–Australian species, 50% screened positive for an A–group strain. One of these species also harboured a B–group strain in a double infection. Various factors that might explain the unusually high incidence of Wolbachia in ants are discussed. In general, Wolbachia may represent a widespread and previously unrecognized party active in the conflicts of interest within social insect colonies.

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