Temporal distribution of, and effect of anthropic modifications on, phlebotomine populations in the Chaco bioregion, Argentina

Abstract

The Phlebotominae (Diptera: Psychodidae) are insects of medical and veterinary importance, because some species are able to transmit pathogens such as Leishmania spp. In the last 20 years, numerous leishmaniasis outbreaks have been reported in the Chaco Bioregion (Argentina), with an increasing trend of cases associated with periurban transmission. The Chaco Bioregion has two sub-regions according to their climatic and ecological characteristics: the Dry Chaco and the Humid Chaco. In the present study, sandfly captures were performed in both sub-regions, at sites with different levels of anthropic modifications, with the aim of describing differential spatio-temporal patterns of potential tegumentary and visceral leishmaniasis vectors. The captures yielded 3559 sandflies of 14 species. Migonemyia migonei (França) was the prevalent species in the Dry Chaco, whereas Mg. migonei and Nyssomyia neivai (Pinto) were co-dominant in the Humid Chaco. Environmental factors such as degree of anthropic modification and climatic factors were found to modulate both the phlebotomine fauna composition and the diversity and abundance of each species. These factors would increase vector abundances, and thus the transmission risk, during warm months with moderate rainfall, especially in areas with higher anthropic modifications. The co-dominance patterns observed in transitional areas could contribute to the transmission of leishmaniases.