Reproductive biology of the Cape honeybee : a critique of Beekman et al.

Abstract

A critique of “Asexually Produced Cape Honeybee Queens (Apis mellifera capensis) Reproduce Sexually”: Laying workers of the Cape honeybee parthenogenetically produce female offspring whereas queens typically produce males. Beekman et al. confirm this observation, which has repeatedly been reported over the last 100 years including the notion that natural selection should favor asexual reproduction in A. m. capensis. They attempt to support their arguments with an exceptionally surprising finding that A. m. capensis queens can parthenogenetically produce diploid homozygous queen offspring (homozygous diploid individuals develop into diploid males in the honeybee). Beekman et al. suggest that these homozygous queens are not viable because they did not find any homozygous individuals beyond the third larval instar. Even if this were true, such a lethal trait should be quickly eliminated by natural selection. The identification of sex (both with molecular and morphological markers) is possible but notoriously difficult in honeybees at the early larval stages. Ploidy is however a reliable indicator and we therefore suggest that these “homozygous” larvae found in queen cells are actually drones reared from unfertilized eggs, a phenomenon well known by honeybee queen breeders.