. 1. The adaptive significance of the timing of growth and reproduction by honeybee, Apis mellifera L., colonies in cold climates was studied by describing the seasonal patterns of food storage, brood rearing, and swarming, and then observing the consequences of experimentally perturbing the seasonal cycles of brood rearing and swarming.

2. Colonies consume large amounts of food over winter (20+ kg of honey), but have only a brief period (about 14 weeks) for food collection each year.

3. The honeybee's striking habits of starting brood rearing in midwinter and swarming in late spring evidently help colonies achieve maximum use of the short summer season. Colonies whose onset of-brood rearing was experimentally postponed until early spring showed greatly retarded colony growth and swarming. Other experiments demonstrated that late swarms starve more often during winter than do early swarms.

4. We conclude that the timings of colony growth and reproduction are essential elements in the honeybee's suite of adaptations for winter survival.

Survival of honeybees in cold climates: the critical timing of colony growth and reproduction

The proportion of a honeybee colony's foragers which locate forage patches by independent scouting, as opposed to following recruitment dances, varies between about 5 and 35%, depending on forage availability. Experienced foragers scout more than do novice foragers. The cost of finding a forage patch is greater for recruits than scouts, but the patches found by recruits are evidently superior to those found by scouts. The honeybee's combined system of recruitment communication, scout-recruit division of labor, and selectivity in recruitment, apparently enhances a colony's overall foraging efficiency by guiding a large majority of a colony's foragers to good forage patches.

Division of labor between scouts and recruits in honeybee foraging

(1983). Some Differences between Temperate European and Tropical African and South American Honeybees. Bee World: Vol. 64, No. 1, pp. 12-21.

Some Differences between Temperate European and Tropical African and South American Honeybees

1. Three major determinants of bees' nectar-foraging patterns are the maximum depth at which nectar is accessible (dependent on bee tongue length) ; the minimum profitable energy content per flower (dependent on foraging costs and hence on bee body mass) ; and the minimum threshold temperature for flight. These form the axes of a three-dimensional template, the competition box. 2. Thresholds of depth, cost and temperature can be identified for each species of bee, delimiting domains within the box compatible with foraging by each bee species. 3. Changes through a day in temperature and in the depth and sugar content of nectar define the nectar trajectory through the box for a flower species in relation to microclimate and bee activity. 4. This approach allows systematic appraisal of the roles of accessibility, energy content and temperature in interspecific competition among bees for nectar, and draws attention to situations in which additional factors may be important. 5. By superimposing a bee-species-specific template on a representative nectar trajectory for a given flower species in a given situation, it is possible to make reasoned guesses about the expected interactions of foraging bee species with a novel flower species and with each other in a novel situation. Such guesses are required for evaluating the expected impact of honey-bees and other introduced pollinators on the pollination system of crops and natural vegetation. 6. Use of the competition box is illustrated in relation to dawn-to-dusk studies involving measurements of nectar concentration and volume, microclimate, flower form, and the tongue lengths and foraging activity of bees of different species.

The competition box: a graphical aid to forecasting pollinator performance

SummaryComparisons of Africanized and European honeybees (Apis mellifera) were made during two periods of different nectar availability in tropical dry forest in Venezuela. Field colonies were used to study honey yields, nectar-load characteristics, and flight activity including flight initiation and cessation. Observation-hive colonies were used to study dance communication and recruitment. Throughout these various measurements significant interactions occurred between geographic type of bee and period of nectar availability. Generally, in conditions of good nectar availability, European bees collected more and larger nectar loads, and produced more honey/colony/day than Africanized bees, possibly because of their more intensive recruitment of foragers. Africanized bees were marginally superior for some variables in conditions of low nectar availability. The results support the conclusion that, based on honey production alone, the European honeybee is the more desirable bee for use in commercial beekeeping.

Honey Production and Underlying Nectar Harvesting Activities of Africanized and European Honeybees

SummaryThe weights of European and Africanized worker honeybees in swarms were determined. European worker were significantly heavier. Within each population, mean weights of workers from different swarms varied greatly, mostly because of differences in the mean weights of honey sac contents. As the weights of worker differed so much between swarms, it is recommended that an estimate of a swarm size should be based on the mean weight of workers sampled from that swarm.

Gard W. Otis

Papers

Weights of Worker Honeybees in Swarms