The Experimental Application of Insecticides from a Helicopter for the Control of Riverine Populations of Glossina tachinoides in West Africa. Part VIII: The Effects of Two Spray Applications of OMS-570 (endosulfan) and of OMS-1998 (decamethrin) on G. tachinoides and Non-Target Organisms in Upper Volta

Abstract

The results of discriminative spraying of endosulfan and decamethrin from a Bell 47G-4A helicopter to fringing riverine forest habitats of Glossina tachinoides in the Komoe Valley, Upper Volta, are described. The insecticides, diluted with diesel oil were applied from the helicopter through a unilateral (left-side) arrangement of four rotary atomisers. Three experimental blocks were each sprayed twice at an interval of about one month, one with endosulfan at individual swath dosages of 100 g (a.i.)/ha, the second with endosulfan at 200 g (a.i.)/ha and the third with decamethrin at 12.5 g (a.i.)/ha. In spite of aerially applied dieldrin barriers there was extensive reinvasion by G. tachinoides during the inter-spray period, consequently conclusions were largely drawn from the data collected before and after the second cycle of insecticide applications. The reinvasion problem is discussed. Endosulfan at 200 g/ha was the most effective in controlling G. tachinoides. Other treatments were less, but probably adequately effective, although the decamethrin was more expensive. Detailed cost analyses are presented. Even though the track of the helicopter was about 15 m from the banks of the R. Komoe, contamination with insecticide was sufficient to adversely affect some aquatic non-target organisms. Decamethrin caused high mortalities of two aquatic prawns, Caridina africana and Machrobrachium raridens. One year later fish and C. africana populations had recovered, but not M. raridens.