The cave-like sense organ in the antennae of Triatominae bugs

Abstract

In the second segment of the antennae of haematophagous reduviids an unusual cave-like organ is found the function os which was investigated in Triatoma infestans. the morphology of the organ makes it difficult to ascribe it to a mechno- 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 finding, habitat selection and circadian synchronization

Olfaction in vector-host interactions

“…All segments bear sensilla, hair-like cuticular structures that house sensory cells of different modalities, including chemoreception, mechanoreception, thermoreception and hygroreception (Barth 1952, Catalá 1994, Catalá and Schofield 1994, Diehl et al 2003, Guerenstein and Guerin 2001, Mayer 1968, Bernard 1974, Insausti et al 1999, Justo and Tramezzani 1977, McIver and Siemicki 1984, Lazzari and Wicklein 1994, Wigglesworth and Gillet 1934.…”

Thermosensation and the TRPV channel in Rhodnius prolixus

“…Triatomines can detect infrared radiation (Lazzari and Núñez, 1989;Schmitz et al, 2000;Zopf et al, 2014aZopf et al, , 2014b and the response is triggered when there is contrast between the source of heat and ambient temperatures (i.e., bugs only respond to stimuli from objects at host's temperature, 30-35°C, provided that the environment is colder than the object; Ferreira et al, 2007;Fresquet and Lazzari, 2011). Heat receptors in triatomines are concentrated on the antennae, but are also present in different regions of the body (Insausti et al, 1999;Lazzari and Wicklein, 1994;Zopf et al, 2014aZopf et al, , 2014b.…”

Pedicellar structures in Reduviidae (Heteroptera) - comments on cave organ and trichobothria

“…Possible functions suggested for the cave organ in haematophagous Triatominae are heat sensation for locating a vertebrate host (Barth, 1952), sensation of thermal stimuli (Lazzari & Wiklein, 1994) and olfactory reception, "possibly enabling molecular testing during flight" (Catala et al 1998). In those Reduviidae which are known to prey on arthropods, e.g., Stenopodainae, Redu viinae and Peiratinae, a function of the cave organ as a heat receptor in the context of prey location is unlikely.…”

“…In these taxa, the cavity is 40 to 150pm long and its epithelium contains bipolar neurons with sensillar pro jections (Catalá et al 1998). Suggested functions of this structure in haematophagous Triatominae include response to heat stimuli (Barth, 1952;Lazzari & Wiklein, 1994) or chemical cues (Catalá et al, 1998). There is one ambiguous indication of this structure in non-haematophagous Reduviidae.…”