FIELD TRIALS WITH VECTOLEX (BACILLUS-SPHAERICUS) AND VECTOBAC (BACILLUS-THURINGIENSIS (H-14)) AGAINST ANOPHELES-GAMBIAE AND CULEX-QUINQUEFASCIATUS BREEDING IN ZAIRE

Under field conditions in Kinshasa, Zaire, an aqueous suspension of Bacillus thuringiensis (H-14), Vectobac(R) (12-AS), lost most of its larvicidal activity at all concentrations after 48 h against Culex quinquefasciatus breeding in polluted gutter water and Anopheles gambiae breeding in clear water irrigation ponds. However, good control of Cx. quinquefasciatus was obtained using a granular formulation of B. sphaericus, Vectolex-G(R) (ABG-6185), at concentrations of 10-30 kg/ha. High concentrations of Vectolex-G gave excellent control of An. gambiae breeding in irrigation ponds. The Vectobac-G was less active against An. gambiae than Vectolex-G, in spite of good dispersion of Vectobac-G particles.