Selectable components of sex allocation in colonies of the honeybee (Apis mellifera L.)

Colonies of social insects that undergo fission as a component of reproduction produce large excesses of males. Hypotheses to explain this phenomenon have assumed that the workers that constitute the entourage for the new queen (or queens) represent investment in female reproductives. Selection for optimal colony sex allocation then leads to an increase in production of males that balances the investment in females based on their relative reproductive values. We show that the construction of comb dedicated to the production of males (drone comb) versus workers (worker comb) is a component of sex investment under the control of colony workers. Relative comb construction was highly correlated with the relative investment in male and worker brood. Colonies that invested relatively more in their total numbers of males invested less in the dry weight of individual workers. Colonies that had more adult workers produced a greater number of males and workers, but colony size did not affect the proportional investment in drone comb or brood. Genetic variability was found for the number of adult workers in colonies, the amount of drone comb produced, the amount of worker comb produced, and the dry weight of adult workers, suggesting that sex allocation is a selectable trait in honeybees.