Ovary activation correlates with the reproductive potential of honeybee (Apis mellifera) workers if they are in a foreign colony

Abstract

In eusocial Hymenoptera, the laying of male-determined eggs by workers in an unrelated colony can be a powerful strategy for increasing direct fitness benefits. A recent study showed that honeybee rebels, which are workers that develop under queenless conditions and have high reproductive potential, drift to foreign colonies, with a preference for hopelessly queenless colonies, and act as reproductive parasites. In our experiment, by introducing 5-day-old rebels and normal workers into foreign queenright colonies, we discovered that only rebels developed a reproductive phenotype by activating their ovaries. In a similar experiment with 1-day-old workers, neither rebels nor normal workers displayed such a tendency. We suggest that workers’ reproductive potential could thus be a key parameter activating the ovaries in not only drifting workers but also workers acting as reproductive parasites. Our results also support the hypothesis that the colony recognition cue probably has an environmental, rather than a genetic, origin.