Blackflies (Simuliidae)

Abstract

All 2330 species of blackflies (family Simuliidae) develop in streams and river where the filter-feeding larvae provide beneficial ecosystem services. Female flies emerge from the water to become pernicious blood feeders and vectors of disease organisms among birds and mammals. About 10–20% of the world's species are pests or vectors of concern for humans and their animals. Their persistent swarming and biting can have severe economic consequences for outdoor enterprises. Blackflies are among the few arthropods that kill animals by direct blood feeding, often via simuliotoxicosis, an incapacitating condition resulting from introduction of excessive salivary components. Simuliid-borne human diseases include onchocerciasis (river blindness) and mansonellosis caused by filarial worms in Africa and Latin America, respectively. Onchocerciasis manifests as skin and ocular pathologies, including irreversible blindness. Mansonellosis is asymptomatic or mild. The most prominent simuliid-borne animal diseases are avian trypanosomiasis and leucocytozoonosis, onchocerciasis, and vesicular stomatitis. Avian trypanosomiasis is typically asymptomatic, but the other diseases can cause health problems. Suppression of blackflies usually involves application of the biological control agent Bacillus thuringiensis variety israelensis against the larvae. The fight against onchocerciasis involves vector control and human treatments with the microfilaricide ivermectin. The disease has been eliminated from most New World foci and its prevalence reduced in Africa.