A membrane feeding technique for the infection of Culicoides nubeculosus mg. and Culicoides variipennis sonorensis coq. with Onchocerca cervicalis Rail. and Henry

The transmission of Onchocerca cervicalis Rail. and Henry in the horse is being investigated at Winches Farm Field Station, St. Albans. Laboratory colonies of Culicoides nubeculosus Mg., the natural vector of O. cervicalis in Europe, and of C. variipennis sonorensis Coq., a North American midge, have been established. A technique has been developed to facilitate the artificial infection of these midges with O. cervicalis. Experimental flies imbibed a meal of O. cervicalis microfilariae suspended in defibrinated ox blood at 38°C. A plucked skin from a one-day-old chick was used as a membrane. 232 C. nubeculosus and 117 C. v. sonorensis were fed and 5·5% of the C. nubeculosus and 7·7% of the C. v. sonorensis subsequently developed infective (3rd stage) larvae. The fact that 3rd stage larvae developed in specimens of C. v. sonorensis is a point of special interest because this midge has not yet been identified as a vector of O. cervicalis.