Larvicidal and Antifeeding Activities of Oriental Medicinal Plant Extracts against Four Species of Forest Insect Pests

Methanol extracts from 77 oriental medicinal plant species in 42 families were tested fro their larvicidal and antifeeding activities against larvae of Lymantria dispar L., Acantholyda posticalis MATSUMURA, Hyphantria cunea DRURY and Dendrolimus spectabilis BUTLER, using leaf-dipping method. Insecticidal and antifeeding activities varied with both plant and insect species. The extracts of Leonurus sibiricus leaves, Cynanchum wilfordii roots and Astragalus membranaceus roots revealed both potent larvicidal and antifeeding activities against L. dispar. Especially, A. membranaceus extract was highly toxic to A. posticalis larvae. Strong antifeeding activity against both L. dispar and H. cunea was obtained from the extract of Jeffersonia dubia roots. As naturally occurring insecticides, these plant-derived materials could be useful as an alternative for synthetic insecticides for managing field populations of these forest insect pests.