Interspecific Hybridization of the Korean Native Bumblebee Bombus hypocrita sapporoensia and the European Bumblebee B. terrestris

Abstract

The large bumblebee <TEX>$Bombus$</TEX> <TEX>$terrestris$</TEX>, indigenous to Europe and adjacent areas and used extensively for high-value crop pollination, has been artificially introduced to several parts of the world. Here we show the occurrence of interspecific hybridization between the bumblebee species <TEX>$B.$</TEX> <TEX>$hypocrita$</TEX> <TEX>$sapporoensia$</TEX> and <TEX>$B.$</TEX> <TEX>$terrestris$</TEX> under laboratory conditions. The mating and oviposition percentages resulting from the interspecific hybridization of a <TEX>$B.$</TEX> <TEX>$terrestris$</TEX> queen with a <TEX>$B.$</TEX> <TEX>$h.$</TEX> <TEX>$sapporoensis$</TEX> male were higher than those resulting from the intraspecific mating of <TEX>$B.$</TEX> <TEX>$h.$</TEX> <TEX>$sapporoensis$</TEX>. Furthermore, a competitive copulation experiment indicated that the mating of <TEX>$B.$</TEX> <TEX>$h.$</TEX> <TEX>$sapporoensis$</TEX> males with <TEX>$B.$</TEX> <TEX>$terrestris$</TEX> queens was 1.2-fold more frequent than the mating of these males with <TEX>$B.$</TEX> <TEX>$h.$</TEX> <TEX>$sapporoensis$</TEX> queens. The interspecific hybridization of a <TEX>$B.$</TEX> <TEX>$terrestris$</TEX> queen with a <TEX>$B.$</TEX> <TEX>$h.$</TEX> <TEX>$sapporoensis$</TEX> male produced either <TEX>$B.$</TEX> <TEX>$terrestris$</TEX> workers or the <TEX>$B.$</TEX> <TEX>$terrestris$</TEX> male phenotype, and the hybridization of a <TEX>$B.$</TEX> <TEX>$h.$</TEX> <TEX>$sapporoensis$</TEX> queen with a <TEX>$B.$</TEX> <TEX>$terrestris$</TEX> male produced <TEX>$B.$</TEX> <TEX>$h.$</TEX> <TEX>$sapporoensis$</TEX> males. Our results indicated that interspecific hybridization occurred between <TEX>$B.$</TEX> <TEX>$h.$</TEX> <TEX>$sapporoensis$</TEX> and <TEX>$B.$</TEX> <TEX>$terrestris$</TEX>. These results suggest that such hybridization will have a negative competitive impact and will cause genetic contamination of native bumblebees.