Body size affects specialization and modularity in the global resin foraging meta-network of stingless bees

Abstract

Bees are in global decline and specialized species might be the most vulnerable to extinctions. Bee conservation can be studied using interaction networks, whose relative importance of nodes might correlate with morphological traits. Specifically, body size could affect flying range and thus influence the set of plant-bee interactions. Although several studies have reported botanical sources of resins in stingless bees, resin foraging networks were rarely assembled. Here we aim to describe the global resin-foraging meta-network of stingless bees, identify the most specialized species, and test how body size influences modularity and specialization. We found a modular and nested structure, in which some modules exhibit significant differences in body size and specialization. Melipona beecheii is the most specialized stingless bee in collecting resins. Body size is positively correlated with specialization, in which larger bees are more specialized to collect resins from a subset of plants, possibly because larger bees with broader flying ranges avoid competition by collecting less disputed resources. Our results demonstrate how resin collection can be analyzed in a meta-network framework to test ecological hypotheses and identify specialized species as candidate priorities for the conservation of stingless bees.