Mitogenomics and the Global Dispersion of Vespula germanica: A Case Study from South Africa Shows Evidence for Two Separate Invasion Events

Abstract

Vespula germanica is currently present in all major world regions outside its native Northern Hemisphere range and poses a biological threat to the invaded ecosystems. The genetic diversity of the species is poorly described in both the native and invaded ranges, thus hampering insights into possible mechanisms of invasion. In South Africa, V. germanica was first detected in 1972, and a recent study concluded that one large or several independent invasion events had occurred. However, the high number of low-frequency haplotypes reported therein raised doubts about the quality of the data. In this study, we reassessed the haplotype diversity of V. germanica in South Africa under improved methodological conditions. New mitochondrial markers were developed using complete mitochondrial genomes of V. germanica that allowed the identification of polymorphic regions and the design of robust species-specific primers. Contrary to two previous studies, only two mitochondrial haplotypes were found in South Africa despite almost doubling the number of sampled nests. It is likely that that the number of haplotypes previously reported was overestimated due to the miscalling of nucleotide positions in the electropherograms. Furthermore, the two haplotypes found have contrasting geographic distributions, which supports the known invasion history for this species. Availability of complete mitochondrial genomes for selection of polymorphic regions and design of robust species-specific primers improved the accuracy of the assessment of V. germanica diversity in South Africa. This approach will also be valuable for studying invasive wasp populations of this and other species globally.