Reproductive conflicts in the Asian honey bees Apis florea and Apis cerana

Abstract

In honey bee (genus Apis) colonies with a queen, workers usually have inactive ovaries. However when colonies become queenless many workers begin to activate their ovaries and lay unfertilized eggs. Differences in relatedness among subfamilies of workers, arising from queen polyandry, is predicted to lead to reproductive conflicts in a queenless colony over which workers should produce the final batch of males. This thesis investigates how these conflicts are played out in terminally queenless colonies of Apis florae and A. cerana. The study showed unequal rates of ovary activation among queenless workers of the red dwarf honey bee, A. florae colonies, suggesting that some subfamilies have the ability to respond to a lack of queen and brood pheromones earlier than others. Furthermore, this research has shown that queenless A. florae colonies are parasitized by eggs of non-natal workers, 35.6% of eggs and 22.5% of pupae were from non-natal workers. Incolonies of the eastern honey bee, A. cerana, the proportion of workers with activated ovaries rapidly increases a few days after queenlessness. Workers from different subfamilies show uniform rates of ovary activation. Like A. florae, eggs and pupae of non-natal workers were found in queenless A. cerana colonies, but proportion of them was less than expected based on number of non-natal workers present. This contrast with A. florae may be due to the different nesting behaviour of the two species, and the very high rates of worker policing found in A. cerana. Finally it was shown that the western honey bee A. mellifera can distinguish queen-laid and worker-laid eggs of the distantly related A. florae, but cannot distinguish queen-laid and worker-laid eggs of its sister taxa A. cerana. This may be evidence for the theoretically predicted 'episode of worker revolution'.