Abstract
The larval development of the north Venezuelan Onchocerca volvulus in the 3 Guatemalan simuliid species, i.e. Simulium callidum, S. ochraceum and S. haematopotum was experimentally studied, as compared with that in S. metallicum, the natural vector in the northern Venezuela. All these 3 species ingested as many microfilariae as did the Venezuelan S. metallicum, while feeding on the infected volunteer. However, most microfilarine ingested by S. ochraceum and S. haematopotum were found damaged probably due to the buccopharyngeal armature. The subsequent migration of the microfilariae occurred in 20% S. callidum but very rarely in the other 2 species, while it took place in 76% S. metallicum. At 22℃, third-stage larvae were found in 8% S. callidum and 3% S. haematopotum, but not in all the 51 S. ochraceum examined 9-14 days postfeeding. In contrast, they were found in 16 or 29% of S. metallicum from Venezuela. Overall, it was indicated that beside S. metallicum, the 2 other Guatemalan blackfly species, S. callidum and S. haematopotum, can, despite the low rates, support larval development of the north Venezuelan O. volvulus to the third stage. Our data do not seem to support the assumption that there is mutual incompatibility of O. volvulus to tee vectors between Guatemala and ncrth Venezuela.
