Abstract
Extracts of Acorus calamus rhizome and Glycosmis mauritiana root bark were evaluated to determine their activity against Aphis craccivora Koch (Homoptera: Aphididae) using dimethoate as standard. The dichloromethane extract of A. calamus rhizome recorded the highest aphidicidal activity, although it was 366 times less active than dimethoate. The extract was found to have fumigative toxicity to aphids. Its contact and residue toxicities were not significant. The active ingredient in the extract is believed to be ? asarone. At a concentration above 2000 ppm, the extract had a residual repellant effect for 2 h on the aphid, while a 1000 ppm extract applied to the 1st instar significantly lowered the fecundity of the resulting adults. Lower aphidicidal activities were shown by the methanol extract of A. calamus rhizome and the dichloromethane extract of G. mauritiana root bark although the activities were significant when compared with the untreated controls.
