Heirs and spares: caste conflict and excess queen production in Melipona bees

The caste conflict hypothesis states that there is potential conflict over the caste fate of totipotent immature females in social insects. In most sp ecies, an immature female has little control over her fate because workers control her nutrition. However, in Melipona bees, immature females should h ave considerable control over their own caste fate because they develop on a provision mass in a sealed cell, and because queens are not larger than w orkers. This may explain why, in Melipona, large numbers of queens are rear ed only to be executed. (Because Melipona colonies are founded by swarms ve ry few reproductive opportunities for adult queens occur.) This study uses a one-locus genetic model to determine the optimum proportion of females th at should develop into queens from the perspective of immature totipotent f emales who control their own caste fate. For a population in which all colo nies are headed by a single, single-mated queen, which is the typical situa tion in Melipona, the optimum rises from 14-20% as male production by worke rs declines from 100% to zero. This agrees well with previous studies which , collectively, give an average of 22% of females developing into queens.