Baker's yeast, an attractant for baiting traps for Chagas' disease vectors

Abstract

We tested the attraction of volatile compounds, produced by the aerobic growth of Saccharomyces cerevisiae on saccharose for Triatoma infestans. For these tests, we exploited the behavioural characteristic of these haematophagous insects of dropping when searching for food. In olfactometer assays, yeast cultures activated and attracted bugs as effectively as a mouse. The attraction of the cultures was significantly reduced when the carbon dioxide released was partially eliminated using potassium hydroxide. Yeast cultures were also tested as lures in a novel trap device. A baited device for trapping Chagas' disease vectors using the behavioural peculiarities of T. infestans and this simple attractant is described.

Olfaction in vector-host interactions

“…Under these experimental conditions, the levels of activation and attraction evoked by yeast do not differ significantly from those evoked by a living mouse (Guerenstein et al 1995). Carbon dioxide is likely the main responsible for the responses to yeast because its removal using potassium hydroxide resulted in a loss of response by the bugs (Guerenstein et al 1995). The high levels of activated (68-85%) and attracted (76-87%) bugs throughout the experiments indicate that the rationale behind the design of the trapping olfactometer is compelling.…”

“…Moreover, the odour from the yeast culture also attracts triatomines in test experiments, as most of the bugs captured fell in the test (yeast) tube while very few were found in the control tube. Under these experimental conditions, the levels of activation and attraction evoked by yeast do not differ significantly from those evoked by a living mouse (Guerenstein et al 1995). Carbon dioxide is likely the main responsible for the responses to yeast because its removal using potassium hydroxide resulted in a loss of response by the bugs (Guerenstein et al 1995).…”

“…In fact, one of the most popular common names for triatomines in Spanish, 'vinchuca' , is a word derived from Quechua, and meaning 'bug that falls' . Taking advantage of this behaviour, an olfactometer was designed to study the attractiveness of different odour stimuli and, furthermore, to test the ability of those odours to capture bugs (Guerenstein et al 1995).…”

“…All tubes have cloth mesh at the bottom whereas below the capturetubes an odour source and its control are placed. Air is pulled out from the release tube and, therefore, an airstream from the odour source (and its control) constantly reaches the release tube via the capture-tubes and the arena (Guerenstein et al 1995). This device has already been useful not only to provide proof of concept for the experimental design of the olfactometers but also to test the odour emission from a culture of yeast (Saccharomyces cerevisiae Meynen ex Hansen, cultured with water and sugar) as activator and attractant for triatomines (Guerenstein et al 1995).…”

“…So, the possibility to exploit olfactory responses to actively attract bugs into traps or detection devices becomes relevant (e.g. Guerenstein et al 1995), as well as the characterisation of their chemosensory system and olfactory responses.…”