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(1) Problems associated with Simulium damnosum s.l. population dynamics and control are discussed in relation to the Onchocerciasis Control Programme in the Volta River Basin. (2) Nulliparous and parous biting rates were observed during the recolonization of Gréchan rapids when larvicide applications were interrupted for 3 months during the dry season. (3) A new method of data analysis is proposed and used to estimate population parameters. (4) A new mathematical model of recolonization is proposed which mimics the key features of the process. The model is used to simulate the effect of larvicide and could form the basis for an investigation of alternative management strategies. [ABSTRACT FROM AUTHOR]

Cytotaxonomic identifications of larvae of members of the Simulium damnosum Theobald (Diptera: Simuliidae) complex collected in forest zones of southeast Ghana and southwest Togo between 1977 and 1996 showed that the Djodji form of Simulium sanctipauli Vajime & Dunbar, a vector of onchocerciasis, was eliminated in 1988 by larvicide operations conducted by the World Health Organization (WHO) Onchocerciasis Control Programme (OCP) in West Africa. No members of the form were identified amongst 997 larvae collected up to 8 years after systematic control operations began in February 1988. The results are discussed in relation to estimates of the numbers of samples required to certify elimination and the possibility that other members of the S. damnosum complex were also eliminated by the OCP. [ABSTRACT FROM AUTHOR]