a1 London School of Hygiene and Tropical Medicine, Keppel Street, Gower Street, London, WCIE 7HT, UK
a2 Onchocerciasis Control Programme, World Health Organization, B.P. 549 Ouagadougou, Burkina Faso
Temephos resistance in savanna cytospecies of Simulium damnosum Theobald s.l. and the forest cytospecies S. sanctipauli Vajime & Dunbar, from West Africa is correlated with an increase in general esterase activity. Metabolism studies indicated that esterase products were the major metabolities in both forest and savanna resistant strains of S. damnosum s.l. compared to the susceptibles. In the presence of an esterase synergist, a large amount of the oxon analogue of temephos was produced by the resistant forest cytospecies S. sanctipauli. This strain is also resistant to chlorphoxim, and it is likely that the increase in oxidative activity observed is connected with the chlorphoxim rather than the temephos resistance. There was no evidence of glutathione transferase-, oxidase- or acetylcholinesterase-based temephos resistance machanisms in the savanna species of S. damnosum s.l.
(Received April 11 1989)
c1 To whom all correspondence should be sent.