Condition-dependent response to changes in pollen stores by honey bee ( Apis mellifera ) colonies with different parasitic loads

Abstract

The impact of a parasitic infestation may be influenced by nutritional state, in both individuals and colonies. This study examined the interaction between pollen storage and the effects of an infestation by the mite, Varroa jacobsoni Oudemans, in colonies of the honey bee, Apis mellifera L. We manipulated the pollen storage and mite infestation levels of colonies, and measured pollen foraging and brood rearing. Increased pollen stores decreased both the number of pollen foragers and pollen load size, while initially at least foragers from colonies with moderate infestations carried smaller pollen loads than those from lightly infested colonies. Over the course of the experiment, all colonies significantly increased pollen-foraging rates and pollen consumption, which was presumably a seasonal effect. Lightly infested colonies exhibited a larger increase in pollen forager number than moderately infested colonies, suggesting that more intense mite infestations compromised forager recruitment. Brood production was not affected by the addition of pollen, but moderately infested colonies were rearing significantly less brood by the end of the experiment than lightly infested colonies. Furthermore, the efficiency with which colonies converted pollen to brood decreased as the pollen storage level decreased and the infestation level increased. The results of this study may indicate that honey bee colonies adaptively alter brood-production efficiency in response to parasitic infestations and seasonal changes.