Queens of stingless bee species (Meliponini) face a reproductive dilemma. If they mate with males with which they turn out to share the same sex determination gene, half of their offspring will consist of males, and the colony's workforce will fall by half, given that effectively only the females are workers.
In addition, males with both paternal and maternal (diploid) genetic material as a result of this unfortunate choice by the queen only consume the resources collected by workers and are usually sterile, contributing to diminished reproductive chances for the colony. A research project supported by the São Paulo Research Foundation (FAPESP) involving a team of scientists in universities of Brazil, Belgium, and the United Kingdom shows that the emergence of diploid males from this type of mating also leads to the death of the queen in colonies of the stingless bee species Scaptotrigona depilis.
According to Ayrton Vollet-Neto, first author of the study, the results suggest that this behavior may be common to all stingless bee species because it occurs in phylogenetically distant genera.
One possible explanation for the death of a queen that doesn't comply with the role of maintaining a proportional rate of worker bees in the colony is that a replacement daughter queen will be able to mate and ensure the colony's survival. Otherwise, the most probable outcome would be the death of the colony. "If the queen is killed quickly, she can be replaced by a daughter that will have a chance to mate with a male that doesn't have the same sex allele," Vollet-Neto said.