, 2009 and Wolfgang et al., 2009) about the low-titre infections not traceable by conventional PCR techniques (i.e. low copy numbers of Wolbachia in the infected individuals) we infer that this could be the case of those populations. buy AZD6244 A possible strategy to confirm the low infection rates on those populations could be to perform a high sensitive nested PCR technique, such as that on Wolfgang et al. (2009), an interesting subject of study in future and further investigation in those Brazilian ants. A positive relationship has also been found between

Wolbachia infections and latitudinal distribution. Northern, central-western, and northeastern populations have low or no Wolbachia infection rates, indicating that incidence is apparently lower in regions with long dry seasons or high daily average temperatures. This has been observed in the beetle Chelymorpha alternans and in ants of the genus Solenopsis ( Ahrens and Shoemaker, 2005 and Keller et al., 2004). The distribution of Wolbachia in S. invicta can be influenced by differences in environmental conditions, with higher Wolbachia prevalence occurring in more southerly temperate populations ( Ahrens and Shoemaker, 2005). The higher frequency of some Wolbachia strains in colonies from southern and southeastern regions

might be due to infection by a strain in several local populations, or even a strain in many populations C59 wnt of two or more species. The polytomies found in the phylogenic analysis support this hypothesis. The high frequency of a few strains might also be a consequence of the original foundresses infected (founder effect) with Wolbachia and their expansion in these regions. The “satellite” strains ( Fig. 2), which are linked to more frequent Adenosine variants, might result from few differences in gene sequence due to mutations, as described by Ahrens and Shoemaker (2005) or recombination of the most frequent one. All ant populations from Corrientes, Argentina were infected with Wolbachia, with only three variants. Two of them belong to supergroup B, one was found

in most colonies sampled, H26, and another one from supergroup A. The strains of group B are very closely related, and are part of the polytomy revealed in the phylogenic tree ( Fig. 4). These data corroborates the results found in populations from southern Brazil, where Wolbachia infections were more successful and are more abundant. High incidence of Wolbachia infection in ants, as reported in previous studies, was also found in the genus Solenopsis in Brazil. This high incidence might be due to the more favorable conditions of invasion and maintenance of the Wolbachia infection in haplodiploid social hosts when compared with solitary hosts ( Wenseleers et al., 1998). In addition, the occurrence of multiple infections in some nests can influence reproductive conflicts and combined with other reproductive barriers, it might accelerate speciation ( Werren, 1997).