A cold receptor on the tick, Rhipicephalus appendiculatus: Electrophysiological and ultrastructural observations

A sensillum trichodeum on tarsus I of Rhipicephalus appendiculatus displays a tonic impulse frequency at constant temperature but shows a phasic-tonic increased activity when temperature is lowered. Rising temperature has an inhibitory effect. Ultrastructural details show that it bears resemblance to a double-walled sensillum with spoke canals, and has dendrites of seven receptor cells. One of the cells responds to temperature changes. The function of the others is unknown.