Simulium jenningsi Malloch (Diptera: Simuliidae): a vector of Onchocerca lienalis Stiles (Nematoda: Filarioidea) in New York.
Biting flies were collected from the umbilical areas of Onchocerca lienalis-infected cattle in New York (state) from June through September of 1980. Of the 766 flies collected, 705 were Simulium jenningsi. Microfilariae were detected in the midguts of 37 (50%) of 73 females dissected immediately after the flies had fed. The mean number of larvae per positive fly (fly with microfilariae) was 15.2. Third-stage larvae were recovered from 25 (21.9%) of 114 S jenningsi dissected 8 to 13 days after they had fed on the infected cattle; the mean number of 3rd-stage larvae per positive fly was 3.5. Dissections of flies performed on days 1 through 7 after feeding yielded various numbers of 1st and 2nd-stage larvae from the thoracic muscles. Ovarian dissections performed on 304 S jenningsi attacking cattle indicated an overall parous rate of 58%. Naturally occurring infections with filarial larvae indistinguishable from O lienalis were found in 7.3% of the parous females. Three of these flies, or 1.7% of the parous collection, harbored 3rd-stage larvae. The onset of naturally occurring filarial infections in the population of S jenningsi coincided with a peak in the parous rate in late June. Thereafter, filarial infections were generally detected when the parous rate was above 50%.
D000818:Animals; D002417:Cattle; D002418:Cattle Diseases / Q000635:transmission*; D004175:Diptera / Q000469:parasitology*; D005260:Female; D007303:Insect Vectors; D007422:Intestines / Q000469:parasitology; D008842:Microfilariae; D009518:New York; D009854:Onchocerca; D009855:Onchocerciasis / Q000635:transmission / Q000662:veterinary*; D012621:Seasons