Behaviour of Individual bumble bees (Bombus impatiens) on blueberry (Vaccinium angustifolium) flowers: the effects of pollen and nectar deprivation
France Landry; C M S Plowright; R C Plowright;
The effect of resource deprivation (pollen and nectar) on individual foraging behaviour by bumble bees (Bombus impatiens) from two colonies was examined. For the first colony, the same three workers were observed on blueberry flowers (Vaccinium angustifolium) in the laboratory in three conditions: (1) deprived of nectar; (2) deprived of pollen; (3) deprived of both. We distinguished between flower visits in which vibrating the anthers (buzzing) for pollen either was or was not observed. The proportion of buzzes was greater when the colony was deprived of pollen than when it was deprived of nectar. When deprived of both resources, pollen collection behaviour was yet more frequent, suggesting that pollen can serve, at least in part, as a substitute for nectar. For the second colony, a group of 15 bees was used. Four to eight bees were observed for each of the three conditions. Group proportions of buzzing were significantly higher in the pollen deprivation than in the nectar deprivation condition. This group effect was reflected in individuals observed in both conditions. When the colony was deprived of both resources, however, an intermediate level of buzzing was observed. This study demonstrates not only sensitivity to food reserves, but also adjustment of individual behaviour in response to shortages.