Effect of Queenlessness on Worker Survival, Honey Gain and Defence Behaviour in Honeybees
SummaryThe effects of queenlessness on worker honeybees (Apis mellifera?) were tested with 50 colonies in groups of 10 (five treatments and two replicates) in August, October and December, 1984 and February and April, 1985 in Baton Rouge, Louisiana. The 10 colonies in each group were all from a single heterogeneous mixture of bees, and each colony began with about 6000 workers and no brood. The five treatments each lasted for 28 days and consisted of (1) caged queen for 28 days, queenless for 0 days; (2) caged queen for 21 days, queenless for 7 days; (3) caged queen for 14 days, queenless for 14 days; (4) caged queen for 7 days, queenless for 21 days and (5) caged queen for 9 days, laying queen for 19 days (control). With prolonged queenlessness worker survival, colony weight gain and defence behaviour (number of stings) decreased. Queenlessness did not induce drifting.
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 found a representative parameter for pollen consumption. Midguts of bees of successive ages were analyzed and correlated with various parameters. The relative proportions of sugar, protein and water were either constant or negatively correlated with midgut weight. Only the relative pollen weight (percent of midgut dry weight) increased. (2) To investigate the influence of different levels of brood on pollen consumption of 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 (3-10d), remained on an elevated level in middle-aged-bees (10-18d) and decreased relatively sharply towards the foraging ages (>21d). When queens were caged in the experimental colonies, the following decline of brood cells affected the consumption of pollen differently. 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 middle-aged (10, 14, 18d) worker bees was significantly reduced, while it was clearly elevated in older bees. We discuss pollen consumption as an adaptation to reduced necessity to nurse brood in young and middle-aged bees, and to enhance life span in older animals.
Laboratory Test of the Response to an Alarm Chemical, Isopentyl Acetate, by Apis tnelufera,
A laboratory test was developed to measure the response to isopentyl acetate (IPA) by the honey bee, Apis mellifera L. Bees 2-5 days old showed clear responses measured as seconds to react, duration of the reaction, and intensity of the reaction. An interval of 15 min or more between repeated tests was sufficient to produce consistent results. Groups of 10, 25, or 50 bees were adequate to evaluate a reaction, but a group of 5 was not. Increasing concentrations of IPA in paraffin oil (from 1:10,000 to 1:2) produced quicker, longer lasting, and stronger reactions. Measurements of the response by genetically defined bees using the lab test agreed with evaluations of their temperament in the field.