Morphological variation in relation to flower use in bumblebees

Abstract

AbstractTo understand resource partitioning in a bumblebee community, we analyzed various morphological characters. A total of 1269 individuals of six bumblebee species, Bombus ardens, B. hypocrita, B. diversus, B. ignitus, B. honshuensis and B. beaticola, were examined and principal component analysis showed that the bumblebee species were clearly differentiated. Glossa, prementa and head lengths were positively correlated with the second component, and a longer proboscis was associated with a narrower body, which may help bees to intrude into and access deep‐lying nectar sources. Bombus diversus, with a long proboscis and narrow body, preferred flowers with a long corolla tube, whereas B. hypocrita and B. ignitus, which have short proboscises and wide bodies, visited flowers with short corollas or dish‐shaped flowers. Two pairs of consubgeneric species that have similar morphological characteristics, B. ardens and B. beaticola, and B. hypocrita and B. ignitus, divided flower resources by habitat selection and seasonal partitioning. For resource partitioning among bumblebee species, not only morphology but also other factors, such as habitat and seasonal preference, flower use, foraging behavior, and interspecific interactions, are responsible.