Preliminary assessment of larvicidal activity of Ageratum conyzoides (L.) flower and Spinosad against Aedes aegypti (Diptera: Culicidae): A vector of dengue fever

The larvicidal potentials of aqueous extract of Ageratum conyzoides L. (Asteraceae) flower was compared with Spinosad against 4th or 5th instar Aedes aegypti (Diptera: Culicidae) at 1, 2, 3 and 4 percent volume per volume (v/v). Dichlorvos and distilled water served as positive and negative control, respectively. Mortality data collected at 0.5, 1.0, 1.5, 2.5 and 3.0 hours after treatment (HAT) were subjected to analysis of variance. The lethal time (LT50 and LT90) were estimated using probit analysis. At 2.0-3.0 HAT, Dichlorvos was consistently superior (90.00%) to other treatments, while Spinosad evoked 49.45-85.40% mortality compared to 49.50-69.55% mortality observed in 4% v/v A. conyzoides. There was no significant difference in the LT50 of A. conyzoides applied at 4% v/v and Spinosad. Ageratum conyzoides showed lower toxicity capability against A. aegypti than Dichlorvos.