Auswirkungen der Verdunstungskühlung und der Stoffwechselwärme auf die Körpertemperatur der Schabenarten Periplaneta americana und Blaberus trapezoideus

Abstract

Transpiration and body temperature are measured simultaneously and continuously on living cockroaches. Following an increase of the ambient air temperature by 3°C, 45 min are required in P. americana and 30 min in B. trapezoideus for the adjustment of the body temperature to the changing temperature of the surroundings. When kept in dry air (r.h. < 15%) there was no difference between air and body temperature of P. americana up to 32°C. With increasing temperatures the body temperature dropped below air temperature (at 39°C by 0.8°C) because, we assume, of increasing transpiration. Because the same effect could be seen in dead insects this lowering of body temperature is not accomplished by active regulation of the body temperature. Under condition of moist air (r.h. > 95%) the body temperature was always somewhat higher than the surrounding temperature (at 26°C by 0.1, at 39°C by 0.7°C). The body temperature of B. trapezoideus did not decrease below the surrounding temperatures. Under conditions of dry air there was no difference up to 23°C. At 37°C the body temperature was even higher by 0.4°C. In moist air the body temperature was always above the surrounding air temperature. The difference increased with rising air temperature (at 39°C by 1.2°C.) A comparison of heat produced by metabolism and lost by transpiration correlates with the registered body temperature in P. americana. Under condition of dry air heat loss due to cooling by transpiration always exceeds the heat produced by metabolism, in humid air the latter one is higher. The difference is enlarging with increasing temperatures. Accordingly the body temperature under conditions of dry air finally drops below the surrounding temperature. In humid air, however, the body temperature exceeds the surrounding air temperature.