Vector competence of some neotropical sandflies for the Leishmania (Viannia) braziliensis complex.

Abstract

To evaluate the vector competence of some Lutzomyia spp. (Diptera: Psychodidae) for Leishmania (Viannia) spp. (Kinetoplastida: Trypanosomatidae), experimental infections of anthropophilic sandflies from the Colombian Pacific coast were performed, through membrane feeding and xenodiagnosis on hamsters infected with Le. (V.)braziliensis or Le. (V.)panamensis. Wild-caught or F1 generation females of Lutzomyia gomezi, Lu. hartmanni, Lu.panamensis and Lu.trapidoi were allowed to feed on hamster lesions and then maintained at 26 degrees C and > 80% r.h. on a sugar-water diet until dissection on the fifth day post-infection (p.i.). Despite similar infection rates (range 37-44%) in both Lu.gomezi and Lu.trapidoi, infections were heavier (> 100 parasites) in the latter species. Infections of Lu.trapidoi with Le.braziliensis (n = 21) and Le.panamensis (n = 27) showed parasite migration toward the foregut, with promastigote colonization of the stomodeal valve and appearance of infective forms. In contrast, infections of Lu.gomezi with Le.braziliensis (n = 10) and Le.panamensis (n = 5) were light (< 50 parasites) and usually restricted to the pylorus. In Lu.hartmanni, only a few promastigotes were found in the pylorus and midgut of 3/8 specimens infected with Le.braziliensis, and no Le.panamensis developed (n = 19). By day 5 p.i., promastigote colonization of the hind- and midgut by Le.panamensis was observed in 2/4 Lu.panamensis but not Le.braziliensis (n = 3). It was concluded that Lu.trapidoi is a more efficient vector than Lu.gomezi for both Le.braziliensis and Le.panamensis, and that Lu.hartmanni and Lu.panamensis are of minor importance for Leishmania transmission in this endemic area.