Ground spraying trials involving three synthetic pyrethroids: OMS 2012 (BAY FCR 1272, cyfluthrin) w.p. 10%, OMS 2013 (BAY NAK 1654, fenfluthrin) w.p. 5%, OMS 3004 (WL 85871, alphamethrin) w.p. 5%, were carried out in January 1984 against G. palpalis palpalis and G. tachinoides in the Bouaflé human trypanosomiasis focus, Ivory Coast. Two dosages of each formulation were tested as residual spray: 12 g of active ingredient (a.i.) per hectare at a concentration of 0.016% and 48 g (a.i.)/ha at 0.064%, The insecticide was applied by means of the atomiser SOLO PORT 423 and the total area treated was estimated at 29 ha. The results were evaluated during 5 months with Challier—Laveissière biconical traps.
OMS 2013 w.p. 5% at 12 g (a.i.)/ha, had unsatisfactory effect on G. palpalis palpalis and G. tachinoides from the first month after spray. At 48 g (a.i.)/ha this formulation showed a moderate effect on both vectors during the first 3 months after treatment, rate of reduction in apparent density by trapping (A.D.T.) varying between 70 and 90%.
OMS 2012 w.p. 10% at 48 g (a.i.)/ha gave satisfactory results, 92% reduction in A.D.T. of G. p. palpalis during the first 3 months after treatment. OMS 2012 w.p. 10% at 12 g (a.i.)/ha gave 94% reduction in A.D.T. of G. tachinoides during the first 2 months after treatment. At the dosage of 48 g (a.i.)/ha, 97% reduction in A.D.T. of G. tachinoides was recorded through the evaluation period.
OMS 3004 w.p. 5% at 12 g (a.i.)/ha, gave 97% reduction in A.D.T. of G. palpalis palpalis during the first 3 months after treatment. At 48 g (a.i.)/ha, 91–98% reduction in apparent density of G. p. palpalis was achieved during the period of evaluation. The effect of this formulation at 12 g (a.i.)/ha on G. tachinoides, was very pronounced during the first 3 months after treatment, being 99% reduction in A.D.T. At 48 g (a.i.)/ha, 100% reduction was obtained during the first 4 months and more than 99% reduction in 5 months after spray.