scholarly journals ENDOTHERMY IN THE SOLITARY BEE ANTHOPHORA PLUMIPES: INDEPENDENT MEASURES OF THERMOREGULATORY ABILITY, COSTS OF WARM-UP AND THE ROLE OF BODY SIZE

1993 ◽  
Vol 174 (1) ◽  
pp. 299-320 ◽  
Author(s):  
G. N. Stone
Keyword(s):  
Ambient Temperature ◽  
Heat Loss ◽  
Body Mass ◽  
Thermal Power ◽  
Thermal Conditions ◽  
Energetic Cost ◽  
Solitary Bee ◽  
Warm Up ◽  
Ambient Temperatures ◽  
Thoracic Temperature

1. This study examines variation in thoracic temperatures, rates of pre-flight warm-up and heat loss in the solitary bee Anthophora plumipes (Hymenoptera; Anthophoridae). 2. Thoracic temperatures were measured both during free flight in the field and during tethered flight in the laboratory, over a range of ambient temperatures. These two techniques give independent measures of thermoregulatory ability. In terms of the gradient of thoracic temperature on ambient temperature, thermoregulation by A. plumipes is more effective before flight than during flight. 3. Warm-up rates and body temperatures correlate positively with body mass, while mass-specific rates of heat loss correlate negatively with body mass. Larger bees are significantly more likely to achieve flight temperatures at low ambient temperatures. 4. Simultaneous measurement of thoracic and abdominal temperatures shows that A. plumipes is capable of regulating heat flow between thorax and abdomen. Accelerated thoracic cooling is only demonstrated at high ambient temperatures. 5. Anthophora plumipes is able to fly at low ambient temperatures by tolerating thoracic temperatures as low as 25 sC, reducing the metabolic expense of endothermic activity. 6. Rates of heat generation and loss are used to calculate the thermal power generated by A. plumipes and the total energetic cost of warm-up under different thermal conditions. The power generated increases with thoracic temperature excess and ambient temperature. The total cost of warm-up correlates negatively with ambient temperature.

Thermoregulation of African and European Honeybees during Foraging, Attack, and Hive Exits and Returns

1979 ◽  
Vol 80 (1) ◽  
pp. 217-229 ◽  
Author(s):  
HEINRICH BERND
Keyword(s):  
Metabolic Rate ◽  
Ambient Temperature ◽  
Heat Loss ◽  
Warm Up ◽  
Ambient Temperatures ◽  
Thoracic Temperature

1. While foraging, attacking, or leaving or returning to their hives, both the African and European honeybees maintained their thoracic temperature at 30 °C or above, independent of ambient temperature from 7 to 23 °C (in shade). 2. Thoracic temperatures were not significantly different between African and European bees. 3. Thoracic temperatures were significantly different during different activities. Average thoracic temperatures (at ambient temperatures of 8–23 °C) were lowest (30 °C) in bees turning to the hive. They were 31–32 °C during foraging, and 36–38 °C in bees leaving the hive, and in those attacking. The bees thus warm up above their temperature in the hive (32 °C) before leaving the colony. 4. In the laboratory the bees (European) did not maintain the minimum thoracic temperature for continuous flight (27 °C) at 10 °C. When forced to remain in continuous flight for at least 2 min, thoracic temperature averaged 15 °C above ambient temperature from 15 to 25 °C, and was regulated only at high ambient temperatures (30–40 °C). 5. At ambient temperatures > 25 °C, the bees heated up during return to the hive, attack and foraging above the thoracic temperatures they regulated at low ambient temperatures to near the temperatures they regulated during continuous flight. 6. In both African and European bees, attack behaviour and high thoracic temperature are correlated. 7. The data suggest that the bees regulate thoracic temperature by both behavioural and physiological means. It can be inferred that the African bees have a higher metabolic rate than the European, but their smaller size, which facilitates more rapid heat loss, results in similar thoracic temperatures.

An Analysis of Pre-Flight Warm-Up in the Sphinx Moth, Manduca Sexta

1971 ◽  
Vol 55 (1) ◽  
pp. 223-239 ◽  
Author(s):  
BERND HEINRICH ◽  
GEORGE A. BARTHOLOMEW
Keyword(s):  
Ambient Temperature ◽  
Manduca Sexta ◽  
Heat Production ◽  
Blood Circulation ◽  
Cardiac Activity ◽  
Warm Up ◽  
Ambient Temperatures ◽  
Thoracic Temperature ◽  
Wing Vibration ◽  
Rate Of Increase

The physiology of pre-flight warm-up in Manduca sexta was analysed with regard to rate of heat production, regional partitioning of heat between thorax and abdomen, and the control of blood circulation. 1. When moths which have come to equilibrium with ambient temperature undergo pre-flight warm-up, the thoracic temperature increases linearly until flight temperature (37-39 °C) is approached. 2. The rate of increase in thoracic temperature during warm-up increases directly with ambient temperature from about 2 °C/min at 15 °C to about 7.6 °C/min at 30 °C. 3. The temperature of the abdomen remains near ambient throughout the period of warm-up, but during the initial part of post-flight cooling while thoracic temperature declines sharply abdominal temperatures rise appreciably. 4. During warm-up the rate of wing vibration increases linearly with thoracic temperature. At a thoracic temperature of 15 °C the rate is about 8/sec and at 35 °C it is about 25/sec. 5. When resting animals are held by the legs they at once begin to beat their wings through a wide angle. These wing beats at any given thoracic temperature are slower than the wing vibrations characteristic of normal warm-up, but they cause thoracic temperature to increase at almost the normal rate. 6. The removal of thoracic scales causes a decrease in rate of warm-up, but in still air this does not prevent the moths from reaching flight temperature. 7. During cooling the rate of decrease in thoracic temperature is greater in live animals than in freshly killed ones. At any given difference between thoracic and ambient temperatures cooling rates are directly related to thoracic temperature. 8. In resting moths heart pulsations are usually variable with regard to rate, amplitude, rhythm, and sometimes direction, but the records of cardiac activity simultaneously obtained from thorax and abdomen show close correspondence. 9. During warm-up the records of changes in impedance from electrodes in the abdomen indicate that pulsations of the abdominal heart are either absent, greatly reduced, or at a frequency different from that simultaneously recorded from the thorax. 10. The calculated rate of heat production during warm-up is linearly related to thoracic temperature. 11. Our data are consistent with the assumption that heat produced in the thorax during warm-up is sequestered there by reduction in blood circulation between thorax and abdomen. 12. Rates of warm-up in insects are close to the values predicted on the basis of body weight from data on heterothermic birds and animals.

Effects of Ambient Temperature on Warm-Up in the Moth Hyalophora Cecropia

1973 ◽  
Vol 58 (2) ◽  
pp. 503-507
Author(s):  
GEORGE A. BARTHOLOMEW ◽  
TIMOTHY M. CASEY
Keyword(s):  
Ambient Temperature ◽  
Heat Production ◽  
Cooling Curves ◽  
Warm Up ◽  
Ambient Temperatures ◽  
Logarithmic Plot ◽  
Thoracic Temperature ◽  
Hyalophora Cecropia ◽  
The Difference ◽  
Straight Lines

The rates of pre-flight warm-up in adult Hyalophora cecropia (mean weight 3.10g) were measured 24-36 h after eclosion at 15, 20, 25, and 30 °C in still air. 1. The rate of thoracic warm-up increased linearly with ambient temperature, averaging 2.6 °C/min at 15 °C and 6.5 °C/min at 30 °C. 2. Thoracic temperatures typically reached 37-39 °C while abdominal temperatures rarely rose more than 3 °C above ambient. 3. The cooling curves of the thorax at 15° and 25 °C were straight lines and had similar slopes on a semi-logarithmic plot. 4. Our data are compatible with the idea that heat production is dependent on thoracic temperature, and are incompatible with the theory that it depends on the difference between thoracic and ambient temperatures.

Activation of the Fibrillar Muscles in the Bumblebee During Warm-Up, Stabilization of Thoracic Temperature and Flight

1973 ◽  
Vol 58 (3) ◽  
pp. 677-688
Author(s):  
BERND HEINRICH ◽  
ANN E. KAMMER
Keyword(s):  
Heat Production ◽  
Action Potentials ◽  
Spike Frequency ◽  
Warm Up ◽  
Ambient Temperatures ◽  
Heating And Cooling ◽  
Thoracic Temperature ◽  
Flight Muscles ◽  
Frequency Of Action Potentials ◽  
Physical Laws

1. Extracellular action potentials and thoracic temperatures (TTh) were simultaneously recorded from the fibrillar flight muscles of Bombus vosnesenskii queens during preflight warm-up, during stabilization of TTh in stationary bees, and during fixed flight. 2. In most stationary bees during warm-up and during the stabilization of TTh the rate of heat production, as calculated from thoracic temperature and passive rates of cooling, is directly related to the frequency of action potentials in the muscles. 3. The rate of heat production increases throughout warm-up primarily because of a greater spike frequency at higher TTh. 4. In stationary bees during the stabilization of TTh at different ambient temperatures (TA) the fibrillar muscles are activated by any in a continuous range of spike frequencies, rather than only by on-off responses. 5. Regulation of TTh in stationary bees may involve not only changes in the rate of heat production but also variations of heat transfer from the thorax to the abdomen. 6. During fixed flight the fibrillar muscles are usually activated at greater rates at the initiation of flight than later in flight, but the spike frequency and thus heat production are not varied in response to differences in TA and heating and cooling rates. 7. During fixed flight TTh is not regulated at specific set-points; TTh appears to vary passively in accordance with the physical laws of heating and cooling. 8. Differences in the TTh of bees in free and in fixed flight are discussed with regard to mechanisms of thermoregulation.

Regulation of Heat Production by Large Moths

1967 ◽  
Vol 47 (1) ◽  
pp. 21-33
Author(s):  
JAMES EDWARD HEATH ◽  
PHILLIP A. ADAMS
Keyword(s):  
Oxygen Consumption ◽  
Heat Loss ◽  
Low Temperatures ◽  
Cooling Curve ◽  
O2 Consumption ◽  
Internal Temperature ◽  
Warm Up ◽  
Temperature Changes ◽  
Thoracic Temperature ◽  
Silk Moth

1. Moths ‘warm-up’ prior to flight at mean rates of 4.06° C./min. in Celerio lineata and 2.5° C./min. in Rothschildia jacobae. The abdominal temperature rises only 2-3° C. during activity. 2. Oxygen consumption of torpid sphinx moths increases by a factor of 2.27 as temperature changes from 26° to 36° C. 3. Oxygen consumption during ‘warm-up’ increases with duration of ‘warm-up’ from about 1000 µl./g. min during the initial 30 sec. to nearly 1600µl./g. min. during the 3rd min. This increase compensates for increasing heat loss from the thorax during ‘warm-up‘. 4. When the moths are regulating thoracic temperature, oxygen consumption increases with decreasing air temperature from a mean of about 400µl./g. min at 31° C. to about 650µl./g. min. at 26° C 5. Values of O2 consumption calculated from the cooling curve of C. lineata are about 85% of the measured values of O2 consumption. 6. The giant silk moth, Rothschildia jacobae, regulates thoracic temperature during activity between about 32° and 36° C. at ambient temperature from 17° to 29° C. Moths kept at high temperatures are active longer, have more periods of activity and expend more energy for thermoregulation than moths kept at low temperatures. 7. Large moths increase metabolism during active periods to offset heat loss and thereby maintain a relatively constant internal temperature. In this regard they may be considered endothermic, like birds and mammals. 8. We estimate that male moths use 10% of their stored fat for thermoregulation, while females may use 50%.

Increased heat loss affects hibernation in golden-mantled ground squirrels

2004 ◽  
Vol 287 (1) ◽  
pp. R167-R173 ◽  
Author(s):  
Alexander S. Kauffman ◽  
Matthew J. Paul ◽  
Irving Zucker
Keyword(s):  
Food Intake ◽  
Heat Loss ◽  
Body Mass ◽  
Complete Removal ◽  
Ground Squirrels ◽  
Control Procedure ◽  
Ambient Temperatures ◽  
Spermophilus Lateralis ◽  
Maintain Body Temperature ◽  
Body Heat

During hibernation at ambient temperatures (Ta) above 0°C, rodents typically maintain body temperature (Tb) ∼1°C above Ta, reduce metabolic rate, and suspend or substantially reduce many physiological functions. We tested the extent to which the presence of an insulative pelage affects hibernation. Tb was recorded telemetrically in golden-mantled ground squirrels ( Spermophilus lateralis) housed at a Ta of 5°C; food intake and body mass were measured at regular intervals throughout the hibernation season and after the terminal arousal. Animals were subjected to complete removal of the dorsal fur or a control procedure after they had been in hibernation for 3–4 wk. Shaved squirrels continued to hibernate with little or no change in minimum Tb, bout duration, duration of periodic normothermic bouts, and food intake during normothermia. Rates of rewarming from torpor were, however, significantly slower in shaved squirrels, and rates of body mass loss were significantly higher, indicating increased depletion of white adipose energy stores. An insulative pelage evidently conserves energy over the course of the hibernation season by decreasing body heat loss and reducing energy expenditure during periodic arousals from torpor and subsequent intervals of normothermia. This prolongs the hibernation season by several weeks, thereby eliminating the debilitating consequences associated with premature emergence from hibernation.

A mechanism by which helium increases metabolism in small mammals

1960 ◽  
Vol 199 (2) ◽  
pp. 243-245 ◽  
Author(s):  
H. A. Leon ◽  
S. F. Cook
Keyword(s):  
Thermal Conductivity ◽  
Oxygen Consumption ◽  
Ambient Temperature ◽  
Skin Temperature ◽  
Heat Loss ◽  
Small Mammals ◽  
Thermal Gradient ◽  
Oxygen Mixture ◽  
Ambient Temperatures ◽  
Long Evans

The oxygen consumption of male Long-Evans rats was determined at three different ambient temperatures in air and in an equivalent helium-oxygen mixture. It was found that when the ambient temperature is near the skin temperature of the rat, the effect of helium is insignificant. If the ambient temperature is lowered, helium induces an increased metabolism over air at the same temperature. Since helium has a thermal conductivity about six times greater than nitrogen, it is concluded that the accelerated metabolism is in response to the greater heat loss in the presence of helium and the magnitude of this response is proportional to the thermal gradient between the animal and the environment.

Liver heat production and temperature regulation in the anesthetized dog

1979 ◽  
Vol 237 (5) ◽  
pp. R334-R339 ◽  
Author(s):  
P. Baconnier ◽  
G. Benchetrit ◽  
M. Tanche
Keyword(s):  
Ambient Temperature ◽  
Heat Production ◽  
Linear Correlation ◽  
Temperature Regulation ◽  
Thermal Conditions ◽  
Calorimetric Method ◽  
Ambient Temperatures ◽  
Blood Flows ◽  
Physiological Range ◽  
Negative Linear Correlation

Liver heat production (LHP) was measured in the anesthetized dog by a new calorimetric method. Blood flows and temperatures were measured at the same points. The method avoided damage of liver innervation and vascularization. Changes of LHP were investigated under different thermal conditions. Measurements at controlled arterial temperatures within the physiological range showed changes of LHP when arterial temperature was randomly increased or decreased. When measured LHP was compared in experiments carried out at different ambient temperatures, a negative linear correlation was found between LHP and the ambient temperature. It was concluded that liver heat production may be a factor in temperature regulation.

Thermoregulation and Control of Head Temperature in the Sphinx Moth, Manduca Sexta

1982 ◽  
Vol 101 (1) ◽  
pp. 1-15 ◽  
Author(s):  
JERI R. HEGEL ◽  
TIMOTHY M. CASEY
Keyword(s):  
Heat Loss ◽  
Temperature Fluctuations ◽  
Heart Beat ◽  
Warm Up ◽  
Ambient Temperatures ◽  
Beat Pattern ◽  
Tightly Coupled ◽  
Higher Temperature ◽  
And Control ◽  
Linear Regressions

Head and thorax temperatures (Th and Tth were tightly coupled during pre-flight warm-up over a range of ambient temperatures (Ta). At Ta = 21 °C, the head reached a significantly higher temperature (Tth = 32 °C) than during exogenous heating of dead moths to the same thoracic temperature (Tth = 26 °C). In free-flying moths, slopes of linear regressions for both Tth and TTh versus Ta were about 0.4. At any Ta, Th remained only about 7 °C below Tth Abdominal temperature varied with Ta with a slope of 1.2 and remained 2–5 degrees above Ta. Cooling constants (min−1) for the head, calculated from cooling experiments with the thorax either at Ta or maintained constant at about 40 °C, yielded similar values. During free flight, as Ta increased from 17 to 32 °C, thoracic heat loss decreased from 36 to 20% of the total heat production, head heat loss decreased from 27 to 8%, and abdominal heat loss increased from 17 to 37%. During warm-up at all Ta's the largest component of energy expenditure was the heat storage and heat loss that occurred from the thorax, followed by that from the abdomen and then by that from the head. Exogenous heating of some live moths resulted in cyclic temperature fluctuations in which Th and Tth changed simultaneously and in opposite directions. During each cycle, the heart beat pattern changed, becoming irregular when Tth was increasing and returning to a regular pattern when Tth was decreasing. Smaller temperature fluctuations in the head occurred at the same rate as the heart beat. These data suggest that the head temperatures observed during pre-flight warm-up and flight are the result of active heat transfer from the thorax via the blood circulation.

Rotary Compressor Performance at Low Ambient Temperatures

2020 ◽  
Vol 28 (04) ◽  
pp. 2050037
Author(s):  
S. Lowrey ◽  
G. Reboux
Keyword(s):  
Ambient Temperature ◽  
Heat Loss ◽  
Heat Pump ◽  
Simulated Data ◽  
Performance Testing ◽  
Rotary Compressor ◽  
Ambient Conditions ◽  
Ambient Temperatures ◽  
Compressor Performance ◽  
Performance Envelope

Small rotary compressors are used in domestic heat pump appliances, for example, in domestic dehumidifiers and heat pump clothes dryers. Compressor performance curves provided by the manufacturer can be based on testing at relatively high ambient temperatures, in some cases as high as 35∘C. This can be much higher compared with the ambient temperature in which the compressor operates when, for example, it is installed in a domestic dehumidifier which can operate in ambient temperatures as low as 10∘C. We have developed a compressor calorimeter to test a small R134a rotary compressor extracted from a commercial domestic dehumidifier and use this to measure compressor performance parameters including the isentropic and volumetric efficiencies and the compressor heat loss fraction. The performance testing has been carried out at ambient temperatures 10∘C, 15∘C, 20∘C and 25∘C for a fixed relative humidity of 70% to compare how the compressor performance varies with the ambient temperature, and to determine how well the compressor performs outside of the performance envelope provided by the manufacturer. The results show that isentropic and volumetric efficiency of these small compressors is relatively insensitive to variation in ambient temperature, even outside of the performance envelope provided by the manufacturer. However, the compressor heat loss fraction can, on average, double from 15% to 30%, between operation at ambient 25∘C and ambient 10∘C. The data obtained in this work is used to construct compressor sub-models for certain ambient temperatures. We show how these sub-models can be used to improve a domestic dehumidifier model for operation at low ambient conditions within the evaporator frosting regime and good agreement is obtained between experimental and simulated data. The authors are not aware of a domestic dehumidifier model designed to work at ambient temperatures within the frosting regime.

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