Vectorial cornpetence of Lutzomyia species from the verrucarum (Diptera, Psychodidae) group found in a Leishmania braziliensis endernic focus in Reventones, Cundinamarca

Abstract

Five groups of wild Lutzomyia females from the verrucarum group, Lutzomyia torvida, Lutzomyia ovallesiand Lutzomyia nuñeztovari, captured in a mountainous coffee-growing site in Reventones (Cundinamarca) where Leishmania braziliensis is endemic, were experimentally infected in order to determine their susceptibility to infection with this parasite and their ability to transmit the parasite to a hamster by biting. All three sand fly species (placed together in the same cage) were fed using chicken membrane with a mixture of cultured promastigotes and human erythrocytes. ln the first two groups, only the sandfly's susceptibility to infection by the parasite was registered. In the other three groups (besides susceptibility to infection) the females which survived to oviposition were allowed to feed on a hamster in order to transmit the parasite by bite. lnfection percentage was calculated from direct observation of the parasite's flagellate form in the gut of dissected females 4 to 7 days after ingesting the infected meal. General infection rates for the five groups ranged from 23.9% to 70.2%. The three species were susceptible to L.brazi1iensi.s infection. In each group Lu.torvida was the most abundant species, followed by Lu.ovallesi. Lu.nuReztovariwas present in low density in al1 groups. The parasite's amastigote form was not observed in any of the hamsters.These results demonstrate that the three species are susceptible to developing and harbouring L.braziliensis in their gut and that al1 of them could be involved in this parasite's transmission in the endemic disease focus in Reventones (Cundinamarca) and that they can at least be considered as being potential vectors.