Response of antennal cold receptors of the catopid beetles,Speophyes lucidulus Delar. andCholera angustata Fab. to very slowly changing temperature

Summary

The antennal cold cells in larval ‘black-hair’ sensilla of the cave beetle,Speophyes lucidulus Delar., clearly respond to rates of temperature change 5 to 10 times lower than any tested on insect cold cells so far: often below 0.0005° C/s or 2° C/h. At a given ambient temperature between 11° C and 15° C, cold-cell impulse frequency was higher when temperature was falling at these rates than when it was rising at them in every one of the twelve cells examined. The mean differential sensitivity to the rate of change was -3340±1071 (imp/s)/(° C/s), in each case two to 5 times greater (sign ignored) than in any cold cell observed previously (Loftus 1969; Corbière-Tichané and Loftus 1983). The differential sensitivity to ambient temperature,-6.8 (imp/s)/° C, was statistically indistinguishable, on the other hand, from the earlier values forSpeophyes.

Antennal cold cells of six first-stage larvae of another Catopid beetle,Choleva angustata Fab., displayed very similar responses to the same stimuli. Its mean differential sensitivities were -8.1+3.9 (imp/s)/° C to ambient temperature and-3790+2190 (imp/s)/(° C/s) to the rate of temperature change. UnlikeSpeophyes this beetle spends only part of its life cycle in caves.