Trypanosoma cruzi infection enhances olfactory response in Triatoma pallidipennis Stål (Hemiptera: Triatominae) to compounds potentially useful for insect control.

In Mexico, Triatoma pallidipennis is a major vector of Trypanosoma cruzi, the causative agent of Chagas disease. Current efforts are focused on developing attractants to control these vectors, using volatile substances derived from vertebrate hosts or compounds known to attract hematophagous insects. However, the efficacy of these compounds in attracting parasite-infected triatomines remains to be evaluated. In this study, we assessed the attractant activity of octenol (1-octen-3-ol), nonanal and a mixture of odorants consisting of ammonium hydroxide, lactic acid and hexanoic acid (in a ratio of 1:0.2:0.4 respectively), at concentrations of 1, 10 and 100 ng on the N3, N4 and N5 nymphal stages of T. pallidipennis, both infected and non-infected with T. cruzi. We also evaluated the synergistic effect of the most effective compounds and doses. All experiments were performed in a laboratory using a Y-type glass olfactometer. We found that both infected and non-infected N3 and N4 nymphs were attracted to low doses of octenol, nonanal and the odorant mixture. Particularly noteworthy was the synergistic effect observed between the odorant mixture and nonanal, which significantly increased attraction of T. cruzi-infected individuals. These findings contribute to the development of baited traps utilising these compounds for monitoring triatomines in epidemiological studies or for mass trapping to control these vectors.