Typologies des entomocénoses benthiques soumises à des épandages d'insecticides antisimulidiens

During the tests in gutters, five insecticides (B.t., Abate, chlorphoxin, carbosulfan and permethrin) employed by the Onchocerciasis Control Programme (OCP) have neither the same toxicity nor the same selectivity against for the principal aquatic taxa. In long run, the utilization of these insecticides led to dry season entomocenose structures characteristic for each product with differ from those observed during the pretreatment period. More the insecticides are estimed toxic in the gutter tests, more the long run typologies differ from the reference ones. The differences are slight for B.t., intermediate for Abate and of stronger magnitude for carbosulfan, chlorphoxim or permethrin. The populations of the taxa react differently to the insecticides; some stay the same or are reduced while others increase, due certainly to their low susceptibility, the shortness of their life cycle or the diminution of the spatial and trophic competition. (Résumé d'auteur