Effect of White Oak Extracts on Feeding by the Colorado Potato Beetle (Coleoptera: Chrysomelidae)

Abstract

Alcohol extracts of white oak, Quercus alba L., leaves and bark inhibited the Colorado potato beetle (CPB), Leptinotarsa decemlineata (Say), from feeding upon treated potato leaves, Solanum tuberosum L., in laboratory and greenhouse studies. Of the three plant parts tested, young leaves, old leaves, and bark, extracts of bark were most deterrent. However, these extracts did not inhibit adult Mexican bean beetles, Epilachna varivestis Mulsant, or Japanese beetles, Popillia japonica Newman, from feeding upon treated bean leaves, Phaseolus vulgaris L., or grape leaves, Vitis labrusca L., respectively. Condensed tannin, (+)-catechin, inhibited feeding of adult CPB by 51% when a concentration of 0.0001 g/ml of water was applied to a leaf disk and 100% inhibition resulted with a concentration of 0.01 g/ml. First instars did not feed on leaves with a 0.01 g/ml concentration of (+)-catechin and died within 4 days. Another form of tannin, tannic acid, also inhibited feeding of adult CPB, but to a lesser degree.