THE RELATIONSHIP BETWEEN POPULATION-SIZE, AMOUNT OF BROOD, AND INDIVIDUAL FORAGING BEHAVIOR IN THE HONEY-BEE, APIS-MELLIFERA L

This study experimentally examines the relationship between colony state and the behaviour of individual pollen and nectar foragers in the honey bee, Apis mellifera L. In the first experiment we test the prediction that individual pollen foragers from colonies with higher brood quantities should exhibit a greater work effort for pollen resources than individual pollen foragers from colonies with low brood quantities. Eight colonies were assigned into two treatment groups; HIGH brood colonies were manipulated to contain 9600+/-480 cm2 brood area; LOW brood colonies were manipulated to contain 1600+/-80 cm2 brood area. We measured colony brood levels over the course of the experiment and collected individual pollen loads from returning pollen foragers. We found that, while colonies remained significantly different in brood levels, individual pollen foragers from HIGH brood colonies collected larger loads than individuals from LOW brood colonies. In the second experiment we investigated the influence of colony size on the behaviour of individual nectar foragers. We assigned eight colonies to two treatment groups; LARGE colonies were manipulated to contain 35000+/-1700 adult workers with 3500+/-175 cm2 brood area, and SMALL colonies were manipulated to contain 10000+/-500 adult workers with 1000+/-50 cm2 brood area. We observed foraging trips of individually marked workers and found that individuals from LARGE colonies made longer foraging trips than those from SMALL colonies (LARGE: 1666.7+/-126.4 seconds, SMALL: 1210.8+/-157.6 seconds), and collected larger nectar loads (LARGE: 19.2+/-1.0 mul, SMALL: 14.6+/-0.8 mul). These results indicate that individual nectar foragers from LARGE colonies tend to work harder than individuals from SMALL colonies. Both experiments indicate that the values of nectar and pollen resources to a colony change depend on colony state, and that individual foragers modify their behaviour accordingly.