Diploid male production and colony demography in a recent bumblebee colonist (Bombus hypnorum)
Ryan Edward Brock, Ryan E. Brock , Kerry Blair , Andrew F. G. Bourke
School of Biological Sciences, University of East Anglia, Norwich, Norfolk, UK; School of Biological Sciences, University of East Anglia, Norwich, Norfolk, UK ; School of Biological Sciences, University of East Anglia, Norwich, Norfolk, UK ; School of Biological Sciences, University of East Anglia, Norwich, Norfolk, UK
Single-locus complementary sex determination may hinder the invasive potential of social hymenopterans (ants, bees, and wasps) since reduced genetic diversity can lead to the production of diploid males (individuals homozygous at the sex determination locus). Diploid males represent a substantial genetic load since they replace workers, thus decreasing colony productivity, and are often sterile. The Tree Bumblebee (Bombus hypnorum) first arrived in the UK in 2001 and has rapidly increased in both its range and abundance. However, the genetic structure of the UK population is relatively unstudied, and may provide clues to B. hypnorum’s ecological success and its route of introduction into the UK. Twenty-eight mature colonies of B. hypnorum were collected and the adult and brood populations were censused to provide demographic data. Following this, 337 male pupae across 17 colonies were genotyped at 16 microsatellite markers, allowing us to estimate diploid male frequency. Nests contained an average of 52.2 workers and 89% of nests had successfully reached the sexual production phase, producing an average of 13.7 and 31.2 queen-destined and male pupae, respectively. Preliminary genotyping of 89 male pupae across five colonies found diploid males in one colony. A full analysis will provide a better estimate of diploid male frequency and allelic diversity across the UK population, allowing us to better understand the interaction of genetic population structure and ecological success in B. hypnorum.