Side-effects of experimental pyrethroid applications for the control of tsetseflies in a riverine forest habitat (Africa)

During tsetse control operations near Bouaflé, Ivory Coast, Africa, a study was made of environmental side-effects of helicopter sprayings with permethrin and deltamethrin on a riverine forest. Terrestrial and aquatic arthropod populations and fish were observed for acute effects. The abundance of the species was assessed by various trapping devices before, during, and after the spraying cycle. Populations of mayfly-larvae and small shrimps (Caridina africana) were virtually eliminated after the spraying cycle. TheEphemeroptera recovered within the same season. Caddis-fly andSimulium-larvae populations were affected but they recovered within each spraying interval. Large shrimps (Macrobrachium vollenhovenii) were paralyzed by the insecticide. Recovery occurred within 48 hr. Among the terrestrial arthropods, the hymenopteran and dipteran populations were significantly affected. No effect was observed on bottom dwelling spiders. The ability of the ecosystems to recover from the disturbance is discussed.