Energetic costs of raising brood in honey bee colonies are high, but heater bees are cheap.

Little is known about the energetic costs to insects of raising young. Honey bees collectively raise young, or brood, through a series of complex behaviors that appear to accelerate and synchronize the timing of brood maturation. These include maintaining the brood nest at warmer and consistent temperatures (33-36 °C) and the exceptional activity of heater bees. Heater bees are a part of the larger group of nurse bees that care for brood by rapidly contracting thoracic muscles to generate high body temperatures, from 42 to 47 °C. Heater bees move among brood cells and display this behavior to regulate the temperatures of individual larvae and pupae. We constructed three sets of experimental hives to explore the energy costs of raising brood in general and the cost of heater bees specifically. One set was designed to estimate the numerical allocation of individuals to the heater bee task. The second set was designed to contain only brood, which eliminated foraging and allowed us to quantify stored honey use when rearing juveniles at 10 and 30 °C. The final set was used to measure the respiration rates and energy expenditure of individual bees displaying resting, walking, heating, and agitated behavior. By integrating honey used by brood-only experimental colonies with whole-colony measurements of honey storage in the literature, we estimated that raising brood costs colonies half of their annual energy budgets stored as honey, or approximately 43.7 ± 0.9 kg·yr-1. We estimated that roughly 2 % of individuals in a colony perform as heater bees. Respiration rates of heater bees (19 mW) were more than those of resting bees (8 mW) but similar to those of walking bees (20 mW) and about half of those that were agitated (46 mW). The energetic cost of heating was more than an order of magnitude lower than the reported values for the energetic cost of flying. By integrating data from our three experimental hives, we estimate that the annual cost of raising brood is relatively high. However, heater bee behavior and physiology may require only about 7 % of the annual honey stored by a colony.

Bees as Biosensors: Chemosensory Ability, Honey Bee Monitoring Systems, and Emergent Sensor Technologies Derived from the Pollinator Syndrome.

This review focuses on critical milestones in the development path for the use of bees, mainly honey bees and bumble bees, as sentinels and biosensors. These keystone species comprise the most abundant pollinators of agro-ecosystems. Pollinating 70%-80% of flowering terrestrial plants, bees and other insects propel the reproduction and survival of plants and themselves, as well as improve the quantity and quality of seeds, nuts, and fruits that feed birds, wildlife, and us. Flowers provide insects with energy, nutrients, and shelter, while pollinators are essential to global ecosystem productivity and stability. A rich and diverse milieu of chemical signals establishes and maintains this intimate partnership. Observations of bee odor search behavior extend back to Aristotle. In the past two decades great strides have been made in methods and instrumentation for the study and exploitation of bee search behavior and for examining intra-organismal chemical communication signals. In particular, bees can be trained to search for and localize sources for a variety of chemicals, which when coupled with emerging tracking and mapping technologies create novel potential for research, as well as bee and crop management.

Long-wave infrared imaging for non-invasive beehive population assessment.

Long-wave infrared imaging is used for non-invasive assessment of the internal population of honey bee colonies. The radiometrically calibrated camera signal is related to the number of frames that are populated by bees inside each hive. This enables rapid measurement of population without opening the hive, which disturbs the bees and can endanger the queen. The best results are obtained just before sunrise, when there is maximum thermal contrast between the hive and the background. This technique can be important for bee hive monitoring or for applications requiring frequent hive assessment, such as the use of bees for detecting chemicals or explosives.