Present progress towards the laboratory colonization of African Simuliidae (Diptera).

Abstract

The laboratory colonization of African simuliids would facilitate critical work on many aspects of their biology and onchocerciasis vectors could be studied away from natural breeding-sites. In addition to a review of the literature of past achievements in this field, the authors' own studies are described: these centred on the Simulium damnosum and S. neavei complexes because they include vectors of human onchocerciasis. Other species studied included vectors of Onchocerca gutturosa and avian Haematozoa. Techniques for collecting the various developmental stages of African simuliids are discussed. Adult simuliids may be kept singly in small containers, or together in larger vessels, and fed on sugar-solutions, fruits or flowers. Only two members of the S. damnosum complex (one not yet identified) and one S. bovis complex species are so far known to mate in captivity. Many African simuliids have been blood-fed in captivity from sources including blood-soaked filter paper, birds, rabbits, man and the McMahon feeding apparatus, but results have been inconsistent and a few species have rarely taken blood. Blood/sugar mixtures have given better results, but in most cases normal oogenesis has not subsequently occurred. Some African simuliids lay eggs when kept in tubes, while others do so if placed in water and/or after decapitation. Although some females either fail to oviposit or retain many eggs, others lay a large number, but usually not all develop. The eggs of one species have been temporarily stored at low temperatures, but required protection from fungal attack. Larval development requires adequate water-flow and correct hydro-chemical conditions. Various rearing techniques are described. An apparatus in which the conditions of the water may be regulated has recently been modified for use with the S. damnosum complex and three members of the complex have been reared successfully so far. The Kibwezi form of the S. damnosum complex has been successfully induced to complete every stage of its life-cycle in the laboratory. The reduction of wastage throughout the life-cycle is now being attempted.