Endothermy and Flight Thresholds for Helicoverpa-Punctigera and Helicoverpa-Armigera (Lepidoptera, Noctuidae)

1993 ◽  
Vol 41 (6) ◽  
pp. 577 ◽  
Author(s):  
M Coombs

Patterns of endothermic warm-up and flight thresholds were determined for Helicoverpa punctigera and H. armigera. Both species utilise endothermic mechanisms of heat gain to raise thoracic temperature (T(th)) to a level at which flight is possible. Endothermic warm-up, accomplished by wing shivering, was possible from a minimum of 3-5-degrees-C. Time taken to warm-up is inversely related to ambient temperature (T(amb)). At T(amb) higher than 28-degrees-C, flight was spontaneous. At T(amb) of 10-25-degrees-C, both species maintain T(th) of 20-30-degrees-C during flight. During free flight both species display independence of T(th) from T(amb) and a narrowing of the thoracic excess (T(exc)) with increasing T(amb). Tethered-flight methodologies are intrusive on normal thermoregulatory balance, manifested as increased dependence Of T(th) on T(amb). Thoracic scales act as thermal insulation, removal of scales acts to increase thermal conductance. Warm-up for both species is energetically more expensive at low T(amb) than at high T(amb). The increased energy requirements for warm-up at low ambients may limit the frequency of warm-up and flight.

1979 ◽  
Vol 80 (1) ◽  
pp. 217-229 ◽  
Author(s):  
HEINRICH BERND

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.


1971 ◽  
Vol 55 (1) ◽  
pp. 223-239 ◽  
Author(s):  
BERND HEINRICH ◽  
GEORGE A. BARTHOLOMEW

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.


1981 ◽  
Vol 94 (1) ◽  
pp. 119-135
Author(s):  
TIMOTHY M. CASEY ◽  
JERI R. HEGEL ◽  
CHARLENE S. BUSER

Thoracic temperature (Tth) during pre-flight warm-up increased linearly with time at all air temperatures (Ta). The rate of pre-flight warm-up increased from 3.3 to 12.7 °C/min between Ta's of 14 and 28 °C. Head temperature remained within a few °C of Tth during warm-up, while ventral abdominal temperature remained within a few °C of Ta. Pulsation rate of the dorsal vessel in the thorax increased directly with thoracic temperature. Wing-stroke frequency (n) varied from 15 s−1Tth = 16 °C to 58 s−1 at Tth = 40 °C and was similar at any given Tth between Ta's of 14 and 28 °C. While stroke amplitude varied significantly between warm-up and tethered flight, stroke frequency was similar for the two activities in the same Tth range. Calculated rates of heat production were tightly coupled to Tth and did not vary with Ta. The change in heat production during warm-up was dependent entirely on changes in frequency of muscle contraction. Stroke work was constant at 0.68 mW between Tth of 15 and 40 °C.


1993 ◽  
Vol 174 (1) ◽  
pp. 299-320 ◽  
Author(s):  
G. N. Stone

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.


1989 ◽  
Vol 143 (1) ◽  
pp. 211-223 ◽  
Author(s):  
G. N. STONE ◽  
P. G. WILLMER

‘Grab and stab’ methods have become standard in the measurement of insect body temperatures. The gradient of the best-fit regression of body temperature on ambient temperature is often used as a measure of the thermoregulatory ability of a species. The temperatures recorded are commonly accepted as slight underestimates of actual values prior to capture due to passive cooling between capture and insertion of the thermocouple. Here we present laboratory experiments involving tethered flight which show that bees often warm up on cessation of flight, and that errors due to warm-up over the time interval typically associated with ‘grab and stab’ sampling may be significant. More importantly, the errors due to warm-up in two species are shown to change with ambient temperature, thus affecting the form of the relationship between ambient and body temperatures. We compare laboratory and field data to illustrate the way in which warm-up errors may exaggerate apparent thermoregulatory ability, and we urge greater caution in the interpretation of ‘grab and stab’ data.


1973 ◽  
Vol 58 (2) ◽  
pp. 503-507
Author(s):  
GEORGE A. BARTHOLOMEW ◽  
TIMOTHY M. CASEY

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.


1997 ◽  
Vol 45 (4) ◽  
pp. 409 ◽  
Author(s):  
Marc Coombs

Flight capacity of female and male moths was age dependent in both H. punctigera and H. armigera using a tethered-flight technique. In H. punctigera, flight capacity increased from the first night following emergence up to Night 4, and was maintained at least until Night 10. In H. armigera, a peak in flight capacity occurred on Night 4, followed by a decline with increasing age. Long-flying moths (> 5 h duration) were evident in both species from the night following emergence. Attainment of reproductive maturity was rapid in both species, with 91% of H. punctigera and 77% of H. armigera ovipositing by Night 3. Hence, the increase in flight capacity recorded for both species during early adult life is coincident with the onset of reproductive activity. Both species retain the capacity for extensive inter-crop and inter-regional movement throughout most of the reproductive phase of their adult lives. Neither successful mating or the absence of adult food sources influenced flight capacity during early adult life.


1985 ◽  
Vol 115 (8) ◽  
pp. 980-985 ◽  
Author(s):  
Susan B. Roberts ◽  
W. A. Coward

1973 ◽  
Vol 58 (3) ◽  
pp. 677-688
Author(s):  
BERND HEINRICH ◽  
ANN E. KAMMER

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.


1967 ◽  
Vol 47 (1) ◽  
pp. 21-33
Author(s):  
JAMES EDWARD HEATH ◽  
PHILLIP A. ADAMS

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%.


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