How Honeybees Keep Their Cool Lab Answers

Diana Shaykh
Roman
January 15, 2015
Period C
Three point essay

How Honeybees Keep Their Cool
Introductions
Many species have the ability to maintain their body temperature within a narrow range, regardless of the temperature of their surroundings, these species are known as endotherms. Scientists have been studying species such as endotherms for years. Recently, scientists came about an observation. How do bees or any endothermic animal, generate the heat required to warm itself? Although Bees are invertebrates, they are one of the few of them to be an endotherm. This observation went into a series of experiments. These experiments revealed that before a bee flies it first shivers, sometimes for a few minutes. This causes a burning of glucose
that generates the heat needed to become airborne. Once the bee is flying, the bees muscles, used for flying, generate enough warmth to maintain the bee’s body temperature required for flight.
These results just led scientist to in a few other observations. For example, how the bees keep themselves from overheating. Other observations helped to lead scientists into the new hypothesis and conclusion that bees by adjusting their metabolic rates in their flight muscles, they're able to maintain their body temperature within a narrow range. Scientists Harrison from Arizona State University and H. Glenn Hall from University of Florida were the two to make these observations and put them into action. Harrison and Hall discovered that although the flying of the bees require a large mass of energy determined by wing surface, weight, and flight speed, the bees depending on the metabolism, manage to maintain homeostasis and stay airborne. These two men took action by
observations, experiments, and then using their results to change science history in the studies of animal diversity.
Observation
What started out as an experiment between flight metabolic rates of African and European honeybees, ended up with a discovery of a new hypothesis. New hypothesis that stated that relatively small increases in air temperature were correlated with substantial decreases in flight metabolic rate and wingbeat frequency. Harrison and Hall used their results to suggest a hypothesis that honeybees may be able to vary their metabolic rate by changing flight muscle performance, and in this way achieve thermoregulation. However, the observed discovery might have other explanations. The air temperature variation in the study occurred as temperatures varied within days. Another possible hypothesis that was brought to attention was that maybe bees that fly in the afternoon, in the warmth, are simply a different age or genetic makeup than bees that fly in cooler weather. A manipulative experiment was required to test the hypothesis.

The Experiment To assess this hypothesis, Harrison gathered a team of researchers to randomly expose honeybees to a few different air temperatures from 20 Celsius to 40 Celsius.
Harrison and his team then measured the thorax and abdominal temperature, metabolic rate, and wingbeat frequencies. While the air temperature increased, the metabolic rates of honeybees were determined by measuring carbon dioxide emissions in bees. They measured the carbon dioxide emissions between the bees that were agitated to keep them flying and in bees that were able to fly undisturbed. Both cases showed a decrease in the metabolic rate with increasing temperatures. The next step to the experiment was to take the body temperatures with a tiny, fast- responding microprobe. The frequency of the wingbeats were determined by using microphones, digitized tape recorders, and sound-editing softwares. The wing-beat frequency part of the experiment showed a decrease with an increase in
temperatures.
The Results
Can flying honeybees vary heat transfer between thorax and abdomen like bumblebees? Using an experiment, thorax temperatures varied much less than air temperature. Which told scientists that honeybees do not thermoregulate like bumblebees. Can flying honeybees vary metabolic heat production with air temperature? Flight metabolic rates decreased forty to fifty percent in bees flying in forty celsius air compared to twenty celsius air which was shown in one of many of the small parts in the experiment. This indicated that honeybees maintain warmth, almost constant thorax temperatures by producing lots of metabolic heat at cool air temperatures, and much less metabolic heat when flying in warm air. How can honeybees differ to metabolic heat production and still hover? Harrison and his colleagues found that the wing-beat frequencies of hovering honeybees fell by sixteen percent, as air temperature increased. These results suggested that honeybees may differ in heat production by varying flight muscle power in a manner that is somewhat comparable to heat production by shivering muscles in mammals. According to this hypothesis, bees in colder air are able to utilize more metabolic fuels and produce more heat due to the flight muscles working harder and the use of more ATP. Experiments to test this mechanism still remain to be done.