FIELD APPLICATION RATE OF NATULAR® SC IN METRIC UNITS TARGETING AEDES ALBOPICTUS

NATULAR®SC, mosquito larvicide, was laboratory and field-tested against Aedes albopictus to determine the application rate in metric units (µl/liter). The objective was to estimate in microliters (µl) the amount of formulated NATULAR SC to apply per liter of habitat water. Replicated dose response experiments were conducted on lab-reared third instar Ae. albopictus under controlled laboratory conditions followed by probit analysis. The median lethal dose, LD50, was estimated to be 0.07 µl/liter (95% C.L. 0.054,0.094). Control mortality was less than 1%. The LD95 was estimated to be 0.54 µl/liter (95% C.L. 0.323,1.265). According to the World Health Organization Pesticide Evaluation Scheme (WHOPES) doubling the LD95 approximates the diagnostic dose and is an estimate of the field application rate. The next step consisted of outdoor field trials in 5-liter buckets. Twelve application rates ranging from 0.1 µl/liter to 2.0 µl/liter were tested. Results indicated 1 µl/liter was an optimum application rate. A major conclusion is no single best application rate will kill 100% of susceptible mosquito larvae. An optimal field rate balances efficacy with minimizing the concentration of pesticide. In every treatment a small probability of larval survival is always present. This is a compelling argument for rotating active ingredients according to their mode of action.