VECTOR COMPETENCE OF SOME NEOTROPICAL SANDFLIES FOR THE LEISHMANIA (VIANNIA) BRAZILIENSIS COMPLEX

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 F-1 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.