The effect of food reserves on the production of sexual offspring in the stingless bee Melipona beecheii (Apidae, Meliponini)

Abstract

A long-term study on the production of sexual offspring in relation to food stores was conducted in the stingless bee Melipona beecheii. Firstly, the production of sexuals was followed during one year in 10 colonies kept under natural conditions. Of the brood produced, 22.9% were males, and of all female brood, 14.6% were queens. Secondly, we measured the effect of experimentally manipulating the amount of food stores. One set of colonies started with 1.5 kg of food reserves and were regularly fed with pollen and nectar while another set were subjected to reduced food reserves of 0.5 kg, and were not given any extra food. Throughout the study, colonies with no treatment had brood and adults of both sexes all year round with no evidence of their presence being linked to swarming. Colonies with reduced food stores produced fewer males (0.7%) and queens (10.5%) than untreated colonies or colonies with enlarged food stores. The production of sexuals in colonies with enlarged food stores (23.4% males, 13.5% queens) did not differ significantly from that under natural conditions.¶We conclude that in Melipona only colonies that have accumulated large food stores produce sexuals that contribute to the reproductive population. This may lead to marked differences in the amount of sexuals produced by different colonies, although at the population level sexuals may be present all year round.