The polygyny of Melipona bicolor : scramble competition among queens

The stingless bee Melipona bicolor is facultatively polygynous, a unique character among the bees. Polygynous colonies were not more productive than monogynous colonies. During the process of provisioning and oviposition of cells (POP) a queen may be either alone or together with one or two other queens. If together, each queen has on average the same chance to lay the egg, indicating that there is no dominance mechanism involved. During the POP, a queen may ingest some of the larval food and a trophic egg laid by a worker. Worker egg laying is less frequent in multiple queen POPs. The most active queen has proportionally more single-queen POPs and more trophic eggs. Such nutritional advantage and the resulting output of eggs could depend on chance, but a lasting qualitative difference among queens probably exists as well. Though we could outline the mechanisms behind the outcome of this scramble competition for egg laying, the adaptive significance of this polygyny remains largely mysterious.