Tragedy of the commons in Melipona bees revisited

Abstract

Melipona stingless bees display a paradoxical overproduction of queens, which are later eliminated by nest-mate workers. Mechanistically, it was suggested that the monoterpenoid geraniol deposited into newly provisioned cells by adult bees would cause larvae to develop into queens in Melipona beecheii . This system could be evolutionarily stable if many of these new queens were to leave the nest and parasitize other genetically unrelated colonies nearby, as was shown to occur in a congeneric species . Here, we use microsatellite markers to test whether queen overproduction could be a strategy by which adult workers control the caste fate of the developing larvae to export copies of their own genes to the rest of the population via queen parasitism in M. beecheii . In addition, we re-examined whether artificially increasing the levels of geraniol indeed caused larvae to develop as queens rather than workers. Contrary to our prediction, we found no evidence for queen parasitism in M. beecheii and observed no effect of geraniol on the rearing of new queens. Together, these results support the original ‘tragedy of the commons' hypothesis for queen overproduction in Melipona bees, where individual larvae selfishly bias their development towards the queen pathway according to their best evolutionary interests.

The queens of the stingless bees: from egg to adult

“…Geraniol can also be found in pollen from different plant species, and it has been hypothesized by van Veen (2018) that the availability of fresh pollen, which in Melipona beecheii is collected in short periods in relatively large quantities, coinciding with gyne production in the colonies, may function as a natural regulatory mechanism which limits the excess production of virgin queens to periods of swarming and supersedure. Contrary, recent research re-examined these hypotheses by artificially increasing the levels of geraniol on female larvae food and revealed no effect of the substance on the rearing of new queens (Oliveira et al 2022).…”

Conflict and conflict resolution in the major transitions

“…In caste fate conflict, female larvae with self-determination that develop as queens thereby fail to become workers, so reducing the size of the workforce. More formally, the evolutionarily stable proportion of queens was higher for individual female larvae than for adult workers [ 62 , 63 ], so conflict in this case again affects colony growth and hence resource acquisition. Lastly, in conflict over male parentage, the anticipation of direct fitness through laying male eggs can affect workers' rates of performance of worker-like behaviours when the queen is alive [ 64 , 65 ], and workers may even abandon the natal colony entirely to produce males in other colonies [ 66 ], both of which phenomena potentially affect resource acquisition.…”

Ruling the unruly: Innovation in ant larval feeding led to increased caste dimorphism and social complexity

“…Specifically, larvae would benefit by becoming queens rather than workers, thereby gaining greater direct reproduction, whereas the colony more often benefits more by producing workers (Bourke and Ratnieks 1999, Ratnieks and Wenseleers 2008, Ratnieks and Helanterä 2009. In cases where caste is likely to be self-determined, as in Melipona bees, many females selfishly choose to become queens at the expense of colony productivity (Wenseleers et al 2003, 2004, Oliveira et al 2022, Ferreira et al 2024. In some stingless bees, larvae can even break into neighboring cells to obtain additional food and consequently develop into queens (Faustino et al 2002, Ribeiro et al 2006).…”