Population genetics of the invasive wasp Vespula germanica in South Africa

The German wasp (Vespula germanica) is a highly successful invader on a global scale. These wasps were first observed in the Western Cape region in South Africa in 1972, and they have the potential to expand their range and cause significant damage to the native biodiversity. Our study used nuclear (DNA microsatellites) and mitochondrial DNA (mtDNA) from 42 wasp colonies to analyse the population genetics of V. germanica in their invaded South African range. We sequenced three mitochondrial genes; cytochrome c oxidase I, cytochrome b and cytochrome c oxidase II. We found six mtDNA haplotypes present in South Africa. Although only a single fertilized queen is sufficient for the establishment of a wasp nest, the probability of a single introduced queen to successfully establish a nest and a population is very small. If multiple queens were introduced at the same time, the probability for more than one haplotype being transferred to the new population increases. Therefore, the true number of queen introductions occurred in South Africa can be inferred to be between two and six. We examined nine microsatellite loci and found weak-to-no genetic sub-structuring, likely due to high dispersal rates. We concluded that German wasps in South Africa maintain a homogenous population with movement of individuals between localities

Lack of genetic structuring, low effective population sizes and major bottlenecks characterise common and German wasps in New Zealand

Invasive species cause severe ecological and economic impacts in their introduced ranges. Vespula wasps, native to Eurasia, are a major threat to New Zealand native ecosystems. Understanding factors that influence the success of wasp invasion is pivotal for the development of control strategies. Here, we compare genetic diversity and structure of Vespula germanica and Vespula vulgaris between regions of their native and introduced ranges using microsatellite markers. Our study found lower diversity and lack of genetic structure for both invasive Vespula species within New Zealand. The significant reduction in allelic richness, gene diversity and effective population size illustrate a major bottleneck in New Zealand V. germanica and V. vulgaris populations. Strong signatures of population structure were found for both Vespula species with two clusters being identified as optimal k, approximately corresponding to the native and the invaded ranges. Our results highlight the fact that the lack of genetic diversity does not impede successful invasions in V. germanica and V. vulgaris and encourage further research into mechanisms that promote the success of invasive social insects. Overall, this study provides insights into the genetics of invasive Vespula wasps that can be useful for the development of efficient management strategies