Behavioral Ecology Advance Access originally published online on March 16, 2005
Behavioral Ecology 2005 16(3):661-666; doi:10.1093/beheco/ari040
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Bumble bees (Bombus terrestris) store both food and information in honeypots
Department of Behavioural Physiology, University of Würzburg, Am Hubland, 97074 Würzburg, Germany
Address correspondence to A. Dornhaus, who is now at the School of Biological Sciences, University of Bristol, Woodland Road, Bristol BS8 1UG, UK. E-mail: a.dornhaus{at}bristol.ac.uk.
Social insect foragers often transmit information about food sources to nest mates. In bumble bees (Bombus terrestris), for example, successful foragers use excited motor displays and a pheromone as communication signals. In addition, bees could make use of an indirect pathway of information flow, via the honey stores. We show here that, indeed, bees in the nest continuously monitor honeypots and sample their contents, thus obtaining information on supply and demand of nectar. When there is an influx of nectar into the nest, the colony deploys more workers for foraging. The number of new foragers depends on sugar concentration. Foragers returning with high-quality sugar solution display more "excited runs" on the nest structure. The recruits' response, however, does not depend on modulated behavior by foragers: more workers start to forage with high quality of incoming nectar, even when this nectar is brought by a pipette. Moreover, we show that the readiness of bees to respond to recruitment signals or incoming nectar also depends on colony demand. When colony nectar stores are full, the response of bees to equal amounts of nectar influx is smaller than when stores are empty. When colony nectar stores are depleted, foragers spend more time running excitedly and less time probing pots in the nest and run with higher average speed, possibly to disperse the alerting pheromone more efficiently. However, more bees respond to nectar influx to empty stores, whether or not this is accompanied by forager signals. Thus, honeypots serve to store information as well as food.
Key words: collective behavior, communication, foraging, information flow, recruitment, social insect.