Measuring the cost of worker reproduction in honeybees: work tempo in an "anarchic" line

Abstract
Worker reproduction is extremely rare in queen-right honey bee (Apis mellifera) colonies, despite the fact that workers are capable of laying eggs and can potentially increase their direct fitness by doing so. Factors that tip selective forces in favour of functional worker sterility may be related to colony-level costs of worker reproduction. We examined one possible cost by comparing work rates of `anarchist' (a selected line showing high rates of worker reproduction) and wild-type honey bees fostered into anarchic and wild-type host colonies. We observed a lower work rate among anarchist workers compared to wild-type workers. The difference was small but significant and likely contributes to the reduced viability of anarchic colonies. This colony-level cost of anarchistic behaviour counterbalances the increased personal fitness of anarchist bees and partly explains the extreme rarity of anarchic honey bee colonies.