Take-off activity and orientation of triatomines (Heteroptera: Reduviidae) in relation to the presence of artificial lights.

We analysed the flying activity of Triatoma infestans and Rhodnius prolixus when confronted to artificial lights of different spectral quality. We found that the presence of light sources (white or ultraviolet) did not affect their spontaneous take-off rate. The comparison between species showed that R. prolixus was more prone to fly than T. infestans. Females of T. infestans initiated flight more frequently than males of the same species. Although the same tendency was observed in R. prolixus, no significant differences were assessed between sexes. Concerning the orienting behaviour of triatomines at take-off in relation to the position of the light source, T. infestans showed a significant tendency to fly towards white light, but a non-oriented response when confronted to UV light or in the absence of a light source. R. prolixus also preferred to fly towards a source of white light and exhibited a non-oriented response with no light. However, when the UV light was presented, these bugs exhibited a bimodal attraction/repellence-behaviour. Our results support true attraction by white light rather than menotaxis or arrival by chance. These findings are discussed in relation to the colonization of human dwellings by Chagas disease vectors.