Insecticidal activity against Aedes aegypti larvae of some medicinal South American plants

The insecticidal activity of 11 extracts from nine South American medicinal plants has been studied using the Aedes aegypti larvicidal assay. Eight of the 11 plant extracts studied showed toxicity against the A. aegypti larvae (LC50 < 500 mu g/ml). The dichloromethane extracts of Abuta grandifolia and Minthostachys serosa demonstrated high larvicidal activity, the most active being the dichloromethane extract of A. grandifolia, with an LC50 = 2.6 mu g/ml (LC100 = 8.1 mu g/ml), indicating an activity 2-fold higher than beta-asarone, a natural botanical insecticide used as a positive control (LC100 = 16 mu g/ml). On the other hand, the dichloromethane extract of M. setosa was quite potent against A. aegypti larvae showing an LC50 = 9.2 mu g/ml (LC100 = 25.2 mu g/ml). The results obtained suggest that the extracts of A. grandifolia and M. setosa are promising as larvicides against A. aegypti larvae and could be useful in the search for new larvicidal natural compounds. (C) 2000 Published by Elsevier Science Ireland Ltd. All rights reserved.