Alteration of the social and spatial organization of the vector of Chagas disease, Triatoma infestans, by the parasite Trypanosoma cruzi

Insects of Triatominae subfamily are vectors of the parasite Trypanosoma cruzi, the etiological agent of Chagas disease affecting millions of people in Latin America. Some of these vector species, like Triatoma infestans, live in the human neighborhood, aggregating in walls or roof cracks during the day and going out to feed on animal or human blood at night. Except for their feeding specialization, these insects share this cycle of activities with many gregarious arthropod species. The understanding of how sex and T. cruzi infection affect their aggregation and geotaxis behavior is essential for understanding the spatial organization of the insects and the parasite dispersion. Experiments with non-infected and infected adults of T. infestans show that the insects presented a high negative geotaxis and aggregative behavior. Males had a higher negative geotaxis and a higher aggregation level than females. The aggregation level and the negative geotaxis were stronger in infected insects than in non-infected ones, the difference between sexes being maintained. The importance of these results is discussed in term of parasitic manipulation, dispersion of the vector and strategy of its monitoring.