Feeding Behavior of Lutzomyia pseudolongipalpis (Diptera: Psychodidae), a putative vector of visceral leishmaniasis in Venezuela

Lutzomyia pseudolongipalpis Arrivillaga & Feliciangeli is the first new sand fly species in the L. longipalpis species complex that has been formally described since it was separated by genetic as well as by morphological characters. It is the putative vector of the American visceral leishmaniasis in La Rinconada, Curarigua, a restricted focus in central western Venezuela. We investigated the feeding behavior of this species. The blood meals from 210 of 429 (48.9%) engorged females caught by CDC light traps were identified by a dot enzyme-linked immuno-absorbent assay using antisera against humans and common domestic animals. We propose a new index, the host selectivity index, which is the number of sand flies fed on a given host relative to the available biomass of that host, as an indicator of the feeding behavior of this phlebotomine sand fly. The host selectivity index is compared with the forage ratio, which is the percentage of sand flies fed on a given host by the percentage which that host represented in the total census of available animals and humans. The most attractive animal for L. pseudolongipalpis in Curarigua was the dog, whereas humans were shown to be relatively unattractive. However, not only selectivity or biomass, but also the accessibility to this host may have influenced these results. The low population density of dogs and the low accessibility of L. pseudolongipalpis to humans in relation to domestic animals might help to explain the sporadic transmission of visceral leishmaniasis in this focus.