Honeybee flight metabolic rate: does it depend upon air temperature?

Abstract

Differing conclusions have been reached as to how or whether varying heat production has a thermoregulatory function in flying honeybees Apis mellifera. We investigated the effects of air temperature on flight metabolic rate, water loss, wingbeat frequency, body segment temperatures and behavior of honeybees flying in transparent containment outdoors. For periods of voluntary, uninterrupted, self-sustaining flight, metabolic rate was independent of air temperature between 19 and 37°C. Thorax temperatures (T th ) were very stable, with a slope of thorax temperature on air temperature of 0.18. Evaporative heat loss increased from 51·mW·g -1 at 25°C to 158·mW·g -1 at 37°C and appeared to account for head and abdomen temperature excess falling sharply over the same air temperature range. As air temperature increased from 19 to 37°C, wingbeat frequency showed a slight but significant increase, and metabolic expenditure per wingbeat showed a corresponding slight but significant decrease. Bees spent an average of 52% of the measurement period in flight, with 19 of 78 bees sustaining uninterrupted voluntary flight for periods of >1·min. The fraction of time spent flying declined as air temperature increased. As the fraction of time spent flying decreased, the slope of metabolic rate on air temperature became more steeply negative, and was significant for bees flying less than 80% of the time. In a separate experiment, there was a significant inverse relationship of metabolic rate and air temperature for bees requiring frequent or constant agitation to remain airborne, but no dependence for bees that flew with little or no agitation; bees were less likely to require agitation during outdoor than indoor measurements. A recent hypothesis explaining differences between studies in the slope of flight metabolic rate on air temperature in terms of differences in metabolic capacity and thorax temperature is supported for honeybees in voluntary flight, but not under agitation.

Pesticide risk assessment in free-ranging bees is weather and landscape dependent

“…Herein, Navigation Evironmental Correlate, thereafter abbreviated as NECs, refer to those extrinsic drivers of bee navigation and flight performances, comprising weather conditions (temperature, cloudiness or visibility of sun) and salient landmarks acting as visual cues for orientation [13][14][15][16][17][18][19][20][21][22] . Homing honeybees rely on a network of learned interconnected vectors for orientation 18 , conceptualized as memorized distances and directions among known locations.…”

“…Ambient temperature affects metabolism and flight speed 17 , for instance with lower wingbeat frequency and higher energy expenditure per wingbeat as ambient temperature decreases from 37°C to 19°C (ref. 22). Overall, temperature jointly with the availability of the sun compass and of the visual landmarks as orientation cues are regarded as key NECs.…”

Standard methods for physiology and biochemistry research inApis mellifera

“…In honey bees, basal or resting metabolism and its temperature dependence (Stabentheiner et al, 2003a;Petz et al, 2004;Kovac et al, 2007), discontinuous gas exchange cycles (Kovac et al, 2007) and energetics of foraging and flying (e.g. Wolf et al, 1989;Harrison and Hall, 1993;Harrison et al, 1996;Woods et al, 2005) have all been investigated so far.…”

“…In such situations individuals want nothing but find an exit out of the chamber to fly home. This may not matter (much) in experiments where flight energetics (Wolf et al, 1989;Harrison et al, 1996;Woods et al, 2005) or the interrelation of thermoregulation and heat production are under investigation (Stabentheiner et al, 2003a. Respiratory and energetic measurements also resemble a natural situation quite well if the bees have freely entered the measurement chamber because they expected a reward therein (Balderrama et al, 1992;Moffatt, 2000;.…”

The influence of soil temperature on the nesting cycle of the halictid bee Lasioglossum malachurum

“…Temperature strongly affects the life of insects including numerous behavioral and physiological processes such as flying ability, mating behavior, and especially the duration of development and survival of larvae (Borrell and Medeiros, 2004;Grafton-Cardwell et al, 2005;Larsson, 1991;Woods et al, 2005). Ground nesting insects like many wasp, bee, and ant species probably depend more on soil temperature than on air temperature with regard to nest-site selection, daily activity patterns, as well as foraging success and sex allocation (e.g., Cameron et al, 1996;Crist and Williams, 1999;Potts and Willmer, 1997;Strohm and Linsenmair, 1998;Vogt et al, 2003;Wuellner, 1999).…”