THE INFLUENCE OF BROOD ON THE POLLEN CONSUMPTION OF WORKER BEES (APIS-MELLIFERA L.)

(1) In midgut dry weight (tissue plus contents) of worker bees we foun d a representative parameter for pollen consumption. Midguts of bees o f successive ages were analyzed and correlated with various parameters . The relative proportions of sugar, protein and water were either con stant or negatively correlated with midgut weight. Only the relative p ollen weight (percent of midgut dry weight) increased. (2) To investig ate the influence of different levels of brood on pollen consumption o f individual bees, midgut dry weights from 2 normally breeding control colonies and 2 brood-reduced experimental colonies were analyzed. In bees from control colonies the pollen consumption increased up to the nursing age (3-10 d), remained on an elevated level in middle-aged-bee s (10-18 d) and decreased relatively sharply towards the foraging ages ( > 21 d). When queens were caged in the experimental colonies, the f ollowing decline of brood cells affected the consumption of pollen dif ferently. After 6 days of caging, with a reduction of open brood only, no effect was seen. After 15 days, and even more pronounced after 23 days when no brood was present, the pollen consumption in young and mi ddle-aged (10, 14, 18 d) worker bees was significantly reduced, while it was clearly elevated in older bees. We discuss pollen consumption a s an adaptation to reduced necessity to nurse brood in young and middl e-aged bees, and to enhance life span in older animals. (C) 1998 Elsev ier Science Ltd. All rights reserved.