Morphological constraints and nectar robbing in three andean bumble bee species (hymenoptera, apidae, bombini)

Abstract

We report differences in foraging behavior of three Andean bumblebee species onflowers of Digitalis purpurea (Scrophulariaceae). Bombus atratus was a potentialpollinator while B. hortulanus and B. rubicundus collected nectar by robbing throughholes. We attribute behavioral differences to physical constraints. B. atratus has alonger glossa and a larger body size and is able to reach the nectaries, whereas B.hortulanus and B. rubicundus have shorter glossae and smaller bodies and probablymust rob nectar through holes at the base of flowers.