Thermal acclimatization does not affect the resting activity of type T 1 trichobothrium in the firebug ( Pyrrhocoris apterus ; Heteroptera)

Abstract

Firebugs (Pyrrhocoris apterus) pass through the winter in adult state. They undergo a series of physiological changes in order to increase their capacity to survive at low ambient temperatures. Nevertheless, even during winter their body temperature can rise up to 28 °C for a few hours on a sunny day, which is comparable to summer conditions. To establish the impact of cold acclimatization on the function of mechanoreceptors, the resting activity of T1type trichobothria warmed up to 20 °C is compared in cold and warm acclimatized animals, as well in animals acclimated to laboratory conditions. In cold acclimatized animals the mean resting activity is 3300 imp/min (SE 90, n=13), in warm acclimatized 3400 imp/min (SE 60,n=15), and in animals acclimated to laboratory conditions 3700 imp/min (SE 130, n=17). The similar trend is observed in the variability of inter-impulse time intervals. The mean coefficient of the interval variation is in both cold and warm acclimatized animals 0.28 (cold SE 0.013,n=13; warm SE 0.010, n=15), and in animals acclimated to laboratory conditions 0.33 (SE 0.012,n=17). These data show negligible differences between the three groups. We can conclude that the resting activity of type T1 trichobothrium remains limited to a narrow range, regardless of the phase of the acclimatization process.