Sand fly (Diptera, Psychodidae, Phlebotominae) abundance and diversity in areas affected by the Sao Francisco River transposition project in Ceara State, Brazil

Background: Entomological surveillance of sand fly vectors was carried out to support leishmaniasis prevention and control measures in areas affected by the Sao Francisco River Transposition Project. Methods: Sand flies were collected monthly between May 2011 and December 2014 in seven municipalities: Missao Velha, Brejo Santo, Lavras da Mangabeira, Iguatu, Mauriti, Jaguaribe and Jaguaretama, in dwellings, peridomicile and forest areas for three consecutive days, for a period of 12 h each day (18: 00 to 06: 00 h). Differences in species composition between sites were tested with Shannon's diversity index, the similarity between habitats was estimated by the Sorensen's qualitative similarity index and, for the most abundant species in each municipality, a standardized index of species abundance was applied. The influence of climatic factors on sand fly population densities was analyzed using Spearman's correlation coefficients. Results: A total of 214,213 sand fly specimens belonging to 18 species were captured. The most abundant species in all municipalities was Lutzomyia longipalpis (Lutz & Neiva, 1912). The municipalities of Mauriti and Missao Velha stand out in terms of high species richness, with the latter exhibiting the greatest diversity. The number of sand flies in the Iguatu, Jaguaribe and Jaguaretama municipality was higher during the rainy months, whereas the populations declined in the drier months; the sand fly population density in other municipalities (Missao Velha, Brejo Santo, Lavras de Mangabeira and Mauriti) showed negative correlation with rainfall. Conclusions: This study confirms the presence of several Leishmania spp. vectors in the seven municipalities affected by the Sao Francisco River Transposition Project, with Lu. longipalpis being the most abundant species at all study sites. Vector populations in these municipalities should be monitored, ultimately to assess the associations between environmental changes and sand fly population dynamics and leishmaniasis transmission risk.