The antennal thermoreceptor of the camel cricket, Tachycines asynamorus

The antennal thermoreceptors of the camel cricket, Tachycines asynamorus, were investigated electrophysiologically and with the scanning electron microscope. In addition, the behaviour of the camel cricket was examined in a temperature gradient.The thermoreceptors were found in coeloconic sensilla together with a pair of antagonistic hygroreceptors. This sensillum comprises a pit (opening dia: ca. 5 μm) and a swollen-tipped and cone-shaped peg (tip dia: ca. 0.5 μm) at the bottom. The sensilla are distributed on the flagellar segments laterally to the body axis.The response to a rapid temperature drop occurred in a phasic-tonic manner. The magnitude of the response increased with an increasing drop in the temperature. The static response was dependent on the adaptation temperature (range of 20–40°C) and was largest when the receptor was adapted to 20–30°C. The sensitivty to rapid temperature drop is also dependent on the adaptation temperature, i.e. it is high when the receptor is adapted to temperatures giving a large static activity.The animals crowded together in an area which was at 20–25°C when subjected to a temperature gradient (10–35°C). The temperature “preferred” by the animals was the same as the temperature at which the receptor was most active and most sensitive.