Triatominae dispersal: which attractans guide the invasion of houses?

CATALÁ SILVIA

Hanoi

Workshop; Epidemiological status of kissing bugs in Vietnam; 2013

WHO/IRD/NAFOSTED/NIMPE

ESKIV workshop, Hanoi, 17-21th of June, 2013 TRIATOMINAE DISPERSAL : Which attractants guide the invasion of houses ? Silvia Susana Catalá CRILAR-Conicet, Mendoza 1. Anillaco, La Rioja, Argentina. scatala@crilar-conicet.gob.ar Keywords. Insect dispersion, infra-red radiation, host odours, host and habitat attractants Triatominae bugs are almost exclusively dependent on homoeotherm vertebrate blood as food-source, but little is known about their mechanisms of orientation to hosts and habitats. Heat and odours guide their dispersal activities facilitating the invasion and colonization of human habitats. The detection of odours represents a crucial task for haematofagous insects in order to find food, mate, oviposition places and refuge. In triatomines, carbon dioxide is the main odorous stimulus to find hosts. The responsiveness to carbon dioxide has a daily rhythm and it is endogenously controlled. Other molecules emanated by the human skin contain chemical compounds also used by blood-feeding insects in their search for blood. Odours from their faeces allow the bugs to find refuges. Experiments with Rhodnius prolixus and Triatoma infestans showed that sensitivities to different odours are adjusted according to their associated behavioural context and moment of the day. Behavioural experiments indicate that Triatominae have very high thermal sensitivity and they can detect and orient to thermal sources with a surface temperature close to that of warm blooded animals. Since the early experiments, heat has been recognised as an important factor for host finding. It is the primary cue evoking the proboscis extension that brings the bugs mouth parts in contact with host skin. Heat can also be perceived at long distances as infrared (IR) radiations. The magnitude and range of infra-red radiation from human as well as from domestic animals and their habitats may be an important cue guiding triatomine dispersion and favouring houses invasion. Studies on Triatoma infestans natural habitat showed that the close relationship between the IR emission of habitats and hosts, and the known sensory and behavioural capacities of triatomines suggest that the most attractive habitats for dispersing bugs would be those at short distance, with a IR radiation indicative of host presence. Dispersal would be favoured in periods of low atmospheric water saturation when IR perception is highest. Research in this area is of considerable interest in relation to triatomine surveillance and to develop new methods to minimise triatomine invasion and colonisation of new habitats.