Effect of Formulation, Concentration, and Application Time on the Efficacy of Bacillus thuringiensis (8-14) Against Black Fly (Diptera: Simuliidae) Larvae Under Natural Conditions
Comparisons of formulations of Bacillus thuringiensis (H-14) de Barjac and different application times were conducted in small streams against Simulium vittatum Zetterstedt in northeast Tennessee. Teknar liquid (wdc), Vectobac (WP), and Bactimos (WP) produced average mortalities of 85, 80, and 61%, respectively, at 10 mg/liter per 1 min (= 10 ppm) 10 to 400 m below the point of application. The efficacy of the 1-min application time of Teknar at 10 mg/liter was significantly higher in terms of mortality and effective carry than the 20-min application at 0.5 mg/liter. Doubling and trebling the concentration of Vectobac WP and Bactimos WP, respectively, increased mortality and carryover that of the rate of 10 mg/liter per min, but was not proportionate to increase in dosage.