The influence of habitat and species attributes on the density and nest spacing of a stingless bee (Meliponini) in the Atlantic Rainforest.

Abstract

T. spinipes lives in perennial eusocial colonies and builds nests exposed on tree branches. Why this habitat generalist with exposed nests cannot nest successfully in forest habitats is intriguing. This study explores the hypothesis this species reaches higher densities in vegetation with open canopies and the subsidiary shading hypothesis, assuming the failure of exposed nests in closed canopy rainforest. As this species shows the basic attributes of territorial foraging groups, the hypothesis of uniform nest spacing is also tested. Comparative field data on nest density and spacing in open canopy vegetation and adjacent closed canopy forest are used to test these hypotheses. In random 40 20x200m plots in rubber groves, 18 nests were recorded. This nest density for a single stingless bee was approximately 36 times higher than in the adjacent rainforest. The high density of nests in the rubber groves is also associated with a regular spatial distribution of nests. The ostensive patrolling distances from the colonies probably operates at short distances, which still corresponds to large territorial areas for such a small stingless bee.We conclude that: this species faces powerful nesting constraints in the ever green and closed canopy of rainforest habitats; as the nest density approaches the density threshold, the patrolling mechanism regulates access to prospective nest sites; the high availability of sunny sites for nesting within the deciduous and open canopy of rubber trees favours the high nest density of T. spinipes and its wide spread distribution where this agroforestry system dominates.

Keywords

• interference competition
• patrolling mechanism
• exposed nest constraint
• territoriality
• rubber groves