Reproductive decisions by honey bee colonies: tuning investment in male production in relation to success in energy acquisition

One way to understand the adaptive design of the life history of a social insect colony is to view the colony as having an investment policy whereby it allocates limited resources among the various physiological functions fostering its growth, survival, and reproduction. Prior work has shown that energy is a limited resource for a honey bee colony and that a colony faces a strong trade-off between energy investment in current reproduction and future survival. Given these facts, we hypothesized that a colony might have a flexible energy investment policy, whereby it adjusts its investment in reproduction in relation to its success in acquiring energy. To test this hypothesis, we manipulated the energy acquisition of colonies and looked for an effect on their reproductive efforts. We found that when a colony experiences difficulty building the energy reserve it needs to survive to the next reproductive season, it trims its allocation of energy to drone production and possibly also to drone maintenance. The mechanisms of social physiology which enable a colony to adjust its investment in male reproductives in relation to its energy budget remain a mystery.