THE CAVE-LIKE SENSE ORGAN IN THE ANTENNAE OF TRIATOMINAE BUGS

In the second segment of the antennae of haematophagous reduviids an unusual cave-like organ is found, the function of which was investigated in Triatoma infestans. The morphology of the organ makes it difficult to ascribe it to a mechano- or chemoreceptive function, but shows some characteristics shared with thermoreceptors of other animals. The electrical activity of sense cells was recorded in the presence of stimuli that evoke behavioural responses in this species, i.e. warm, CO2, lactic and butyric acids at different concentrations. The three compounds tested failed to evoke a response at all concentrations assayed. Only thermal stimulation evinced a clear modification in the electrical activity of the sense cells. Both the morphological and electrophysiological findings support a thermoreceptive function of this this organ, that is only present in insects which rely highly on the thermal cue for food finding, habitat selection and circadian synchronization.