Tree species used for nesting by stingless bees (Hymenoptera: Apidae: Meliponini) in the Atlantic Rain Forest (Brazil): Availability or Selectivity

Abstract

The stingless bees (Meliponini) are numerically dominant in tropical forests and most species depend on preexisting cavities for nesting, mainly tree hollows. However, it is still incipient the knowledge about basic characteristics of forest trees used for nesting. The basic questions addressed in this study include: would appropriate hollows be restricted to a few tree species? Would there be selectivity in the use of tree hollows in the forest? These issues are addressed from the comparison of usage patterns among forest trees in different stages of forest regeneration in the Atlantic Forest (Michelin Reserve in northeastern Brazil). Among 89 nests (from six species) found in tree hollows, in a sampled area of 32 ha of forests, 78.7% were associated with live plants and 21.3% to dead trees. This result does not support the hypothesis of selectivity for living trees, considering the high rate of living trees: dead trees (40:1). Nests were sampled from 41 tree species of 31 genera and 22 plant families. Meliponini species showed no differential association with any tree species. The absence of selectivity of tree species as nesting site is probably due to the high diversity of trees per hectare of Atlantic rainforest. The stingless bees also showed no selectivity for wood hardness, therefore the potential durability of tree hollows probably exerts weak selective pressure on bees, or at least the hardness variation range of trees used for nesting has no important influence on reproductive success of the colonies of stingless bees.