Contact toxicity (CT)
Topical application was used to test contact activity of ethanol extracts against S. exigua. Dilution of the crude extract was prepared at 10 mg per ml of solvent (10 mg: ml) in acetone. Each extract was applied topically at doses of 0.5 μl per insect (5 μg/insect) dorsally to the thorax of larvae of S. exigua, using a Burkard Arnold microapplicator. Controls were determined using acetone. Ten insects were used for each concentration and control, and the experiment was replicated for three times. Both treated and control insects were then transferred to culture boxes (10 insects/ culture boxes) with culture media and kept in incubators at 26 ± 1°C, 70 ± 2% relative humidity. Mortality was observed daily for three days after treatment.