Chapter 14 - Black Flies (Simuliidae)

Abstract

The family Simuliidae includes more than 2,200 species of black flies worldwide. The females of most species require a blood meal to mature their eggs, but only about 10%–20% of species are pests of humans and domesticated animals. The immature stages of black flies are restricted to flowing freshwater where the filter-feeding larvae often play a key ecological role. The blood-feeding habits of the female flies can cause nuisance swarms and biting problems for humans and their animals, resulting in significant economic losses in sectors of society such as agriculture, forestry, and tourism. Black flies are among the few arthropods that have killed animals by excessive blood feeding and acute toxemia (simuliotoxicosis) from their salivary compounds. Human onchocerciasis (river blindness), which is present in the central belt of Africa, Yemen, and isolated foci in Latin America, is the worst public health problem associated with black flies. The disease involves more than 25 vector species and numerous skin and ocular pathologies, sometimes including permanent blindness. Great strides have been made in the control and eradication of human onchocerciasis, especially in the New World, through vector control and ivermectin distribution. Mansonellosis, a mildly pathogenic simuliid-borne disease of humans, occurs in scattered foci in Latin America. Many pathogens and parasites are transmitted by black flies to domesticated animals and wildlife, causing diseases such as bovine onchocerciasis, avian leucocytozoonosis, and vesicular stomatitis. The primary means of controlling black flies is by application of the biological control agent Bacillus thuringiensis var. israelensis to streams and rivers.