Tracking an invasive honey bee pest: mitochondrial DNA variation in North American small hive beetles

We describe the current and past distributions of North American small hive beetles (Aethina tumida) having two distinct mitochondrial DNA haplotypes. A collection of 539 hive beetles showed irregular distributions of these haplotypes across the southeastern US. Beetles from the first collections made in coastal South Carolina showed haplotype NA1, exclusively. This haplotype is less common in Georgia and was not observed in North Carolina. Later collections from this and other parts of South Carolina appear more similar to those found in other states. The body size of beetles was not correlated with their haplotype, suggesting that differences in haplotype frequency do not reflect selection pressures on covarying differences in the genomes of these beetles. We discuss the implications for inferring the number of separate hive beetle introductions to the US, and for estimating the migration dynamics by hive beetles as they expand their ranges in the New World.