Phenology and nest site preferences of wood-nesting bees in a Neotropical lowland rain forest

Abstract

During a two year trap nest study in the forest reserve of the La Selva Biological Station, a total of 450 males, 288 females, and 455 nests from 16 species of solitary bees were collected. Trap nests were set up in six dead and six live trees, at canopy level and at 1.5 m height. Comparison of the phenology among species indicated a general seasonality pattern across two bee families, with peak abundance of nests and adults between May and August and lowest values between December and February. Contrary to an original hypothesis, adult and nest abundance was never negatively correlated with monthly rainfall. The occurrence of maximum values for males, females, or nests coincided with flowering peaks of trees at La Selva found in another study. The more sun-exposed canopy trap nests in dead trees were preferred by most species, but not Centris labrosa, which is assumed to be a rainforest specialist. According to this result, the protection of dead but standing canopy emergent trees for bee conservation in commercially managed forests is emphasized. Egg to adult development periods indicated that multiple generations per year might be common for the species investigated in this study.