Brood Nest Temperature Research Articles

Hot bees in empty broodnest cells: heating from within

Honeybee colonies maintain brood nest temperatures of 33-36 degrees C. We investigated brood nest thermoregulation at the level of individual worker behaviour and the transfer of heat from workers to the brood. Worker bees contribute to the regulation of brood nest temperature by producing heat while sitting motionless on the caps of brood cells. We report here an additional, newly observed heating strategy where heating bees enter empty cells between sealed brood cells and remain there motionless for periods of up to 45 min. Individually marked worker bees on the surface of sealed brood cells maintained thorax temperatures (T(th)) between 32.2+/-1.0 degrees C and 38.1+/-2.5 degrees C (mean +/- S.D.; N=20 bees) with alternating warming and cooling periods. Most of the observed bees made one or several long-duration visits (>2 min) to empty cells within the sealed brood area. T(th) at the time bees entered a cell [T(th(entry))] was 34.1-42.5 degrees C (N=40). In 83% of these cell visits, T(th(entry)) was higher (up to 5.9 degrees C; mean 2.5+/-1.5 degrees C; N=33) than the mean T(th) of the same bee. High values of T(th(entry)) resulted from preceding heating activity on the comb surface and from warm-ups just prior to cell visits during which T(th) increased by up to +9.6 degrees C. Bees inside empty cells had mean T(th) values of 32.7+/-0.1 degrees C (resting bees) to 40.6+/-0.7 degrees C (heat-producing bees) during long-duration cell visits without performing any visible work. Heating behaviour inside cells resembles heating behaviour on the brood cap surface in that the bees appear to be inactive, but repeated warmings and coolings occur and T(th) does not fall below the optimum brood temperature. Bees staying still inside empty cells for several minutes have previously been considered to be 'resting bees'. We find, however, that the heating bees can be distinguished from the resting bees not only by their higher body temperatures but also by the continuous, rapid respiratory movements of their abdomens. By contrast, abdominal pumping movements in resting bees are discontinuous and interrupted by long pauses. Heat transfer to the brood from individual bees on the comb surface and from bees inside empty cells was simulated under controlled conditions. Heating on the comb surface causes a strong superficial warming of the brood cap by up to 3 degrees C within 30 min. Heat transfer is 1.9-2.6 times more efficient when the thorax is in touch with the brood cap than when it is not. Heating inside empty cells raises the brood temperature of adjacent cells by up to 2.5 degrees C within 30 min. Heat flow through the comb was detectable up to three brood cells away from the heated thorax.

Influence of Temperature on Rate of Development and Color Patterns of Queen Honey Bees (Hymenoptera: Apidae)

The effect of temperature on the rate of development and color patterns of two honey bee queen lines (black and yellow) was examined. The queens completed the postcapping period (last instar and pupal stages) in incubators maintained at temperatures corresponding with the natural range found in the brood nest: 30.5, 33.5, and 35.5∘C. The black line required significantly fewer accumulated degree-days for development than the yellow line at all temperatures. The queens from both lines had Significantly more yellow coloration on the integument when they completed the postcapping period at 35.5∘C than at 30.5∘C. These results suggest that brood nest temperatures playa more important role in the rate of development of queen lines and in the phenotypic expression of color patterns than has previously been recognized.

Broodnest Temperature Differences and their Possible Effect on Drone Brood Production and Distribution in Honeybee Colonies

SummarySummer broodnest temperatures recorded with thermocouples in honeybee (Apis mellifera L.) colonies varied in relation to developmental brood stage and position within the broodnest. Areas containing empty drone cells were significantly warmer than those containing empty worker cells, while worker larvae and pupae had significantly higher temperatures than those of drones. Worker brood was maintained at a significantly higher temperature than drone brood in the central broodnest (frames 4–6) while not significantly different in the outer broodnest regions. Drone brood temperatures were significantly lower than those of workers in the upper, lower and peripheral comb octads, while not significantly different in the central octads. In colonies used for temperature readings, the distribution of worker and drone brood was related to broodnest temperature when broodnest position was not considered. A similar relationship, however, was not found for most frame and comb octad positions. Drone pupae distrib...

Stability of oxytetracycline in diets fed to honeybee colonies for disease control

Antibiotic extender patties, pollen patties, and sugar solutions containing oxytetracycline hydrochloride (OTC) were incubated at freezer (−9°C), refrigerator (4°C), room (25°C), and brood nest temperature (34°C) for 1, 2, 3, 7, and 11 weeks to determine the stability of the antibiotic. The OTC in antibiotic extender patties and pollen patties was stable at brood nest temperature for at least 11 weeks. The OTC in sugar solutions degraded within 1 week at brood nest temperature.

Effects of Various Hive Covers, Shading and Ventilation on Honeybees in the Tropics

SummaryA study was made, under tropical conditions, on the effects of various combinations of hive covers, shading and ventilation of hives on brood-nest temperatures, sugar concentration of crop contents of foragers, and the ratio between pollen foragers and other foragers. For all treatments, the ratio of foragers returning to the hive with and without pollen declined during the day, and the sugar concentration of the honey-sac contents of foragers tended to increase, except following rain and cooler weather. The highest brood-nest temperatures were recorded at 10.00 hr and the lowest at 14.00 and 16.00 hr, but no significant difference throughout the day was found between the brood- nest temperatures in test groups and the control group (in hives with plain metal covers).

The Effect of Low External Temperatures on the Brood-Nest Temperatures of a Normal Colony of Bees During Summer

The purpose of the experiment was to determine the brood-nest temperatures of a normal colony of honeybees, when a fairly constant low temperature, below that of the ordinary climatic temperature, was maintained around the hive.