Efficacy of Leaf Extracts from Siam weed, Praxelis and Little ironweed for Controlling Aphid (Lipaphis erysimi Kaltenbach) in Pak-Choy.

Abstract

The efficacy of ethanolic weed extracts was investigated based on their insecticidal, repellent and
antifeedant activity against Lipaphis erysimi Kaltenbach in Pak-Choy. The study was conducted using a laboratory-based Completely Randomized Design (CRD) with three replications. Leaf extracts of three weed species, Siam weed, Praxelis, and Little ironweed, were applied at concentrations of 0.005, 0.010, 0.015, and 0.020 g/mL and compared with an untreated control. At a concentration of 0.020 g/mL, all tested weed extracts exhibited the fastest insecticidal activity, causing 90-9% mortality within 24 hours after application and achieving complete (100%) insect mortality within 48 hours. Siam weed leaf extract at a concentration of 0.020 g/mL repelled 80.00% of aphids at both 12 and 24 h after application. However, at 24 h after application. In addition, aphids exhibited a high number of probing attempts but shorter feeding durations when exposed to 0.020 g/mL extracts of Siam weed and Praxelis. These findings indicate that the 0.020 g/mL concentration of Siam weed leaf extract acted as an insecticide, repellent and suppressed their feeding activity. The results indicate that Praxelis leaf extract at 0.020 g/mL possessed both insecticidal and antifeedant activities against aphids. In addition, Little ironweed leaf extract at the same concentration showed potential for use as a botanical insecticide for aphid control in Pak-Choy.