Heritability of worker ovariole number in the Cape honey bee Apis mellifera capensis

In the honey bee (Apis mellifera), a key feature of the queen/worker caste dimorphism is a dramatic difference in ovariole number. However, even within the worker caste, variation in ovariole number is associated with the variance in reproductive potential. Workers of the Cape honey bee, A. m. capensis, are unique in that they are able to produce diploid female offspring asexually, and as a result, have a highly reproductive phenotype, a central feature of which is high ovariole number. We show that patrilines (subfamilies of full-sister workers sharing a father) within colonies vary significantly in ovariole number. Heritability of ovariole number was significantly greater than zero in two population samples (1991-1992: h (2) = 0.19 +/- A 0.11; 1992-1993: h (2) = 0.57 +/- A 0.19), suggesting a significant additive genetic as well as an environmental contribution to this trait. During the course of this study, we indirectly observed the replacement (supersedure) of a queen by her worker-produced granddaughter, providing confirmation of the reproductive potential of A. m. capensis workers.