Car, M.Bigalke, R.D.2015-11-052015-11-0520151984Car, M. 1984, 'Laboratory and field trials with two Bacillus thuringiensis var. israelensis products for Simulium (Diptera: Nematocera) control in a small polluted river in South Africa', Onderstepoort Journal of Veterinary Research, vol. 51, no. 2, pp. 141-144.0330-2465http://hdl.handle.net/2263/50375The articles have been scanned in colour with a HP Scanjet 5590; 600dpi. Adobe Acrobat XI Pro was used to OCR the text and also for the merging and conversion to the final presentation PDF-format.The effects on Simulium adersi and S. hargreavesi larvae of 2 Bacillus thuringiensis var. israelensis products, the liquid formulation "Teknar" (Sandoz) and a powder formulation produced by the Ben Gurion University, Israel, were compared in the laboratory and in the Pienaars River. This river was heavily polluted with effluent from a nearby sewage works and contained 77 mg/l chloride. In the laboratory S. adersi and S. hargreavesi larvae showed 26; 48; 95 and 100% mortality 6 hours after a 10-minute application of 0,8; 1,6; 3,2 and 16 ppm " Teknar" in rain water. The powder formulation applied at 0,2; 1,0; 2,0 and 30 ppm resulted in a 7; 17; 35 and 100% mortality. In polluted river-water the mortality was 85 % with 16 ppm "Teknar" and 80% with 30 ppm B. thuringiensis powder. In the field trials "Teknar" at 1,6 ppm and B. thuringiensis powder at 3 ppm did not cause any larval mortality at flow rates of 3 060 l/min and 2 040 l/min, respectively. However, 24 hours after application of the powder formulation, numbers of S. hargreavesi decreased significantly (P=0,05) 20m below the application point. A further 24 hours later, after "Teknar" had been applied, the numbers of S. adersi decreased and those of Chironomidae increased significantly. There was a significant increase in S. hargreavesi 200 m downstream after treatment with "Teknar".en©ARC - Onderstepoort and Faculty of Veterinary Science, University of Pretoria (original). ©University of Pretoria. Dept. of Library Services (digital).Veterinary medicineVeterinary medicine -- South AfricaArticle