Anti-insect screening of medicinal plants from Kukrail forest, Lucknow, India

Abstract

Ten medicinal plants were evaluated at a dose of 10mg/ml for insecticidal, ovicidal, feeding-deterrence, growth inhibition and morphogenetic effects against various life stages of a noxious lepidopteran insect-pest, Spilarctia obliqua Walker. The acetone extract of Ageratum conyzoides, methanol extract of Justicia adhatoda, and chloroform extract of Plumbago zeylanica showed strong feeding-deterrence, growth inhibition and ovicidal effects against eggs and larvae of S. obliqua. In addition, the chloroform extract of P. zeylanica also created strong morphogenetic disorders in treated pupae of S. obliqua. The methanol extracts of Chenopodium ambrosioides and Ailanthus excelsa showed only feeding-deterrence and growth inhibitory effects but no ovicidal effect, whereas all the five extracts (hexane, chloroform, acetone, methanol and water) of Catharanthus roseus exhibited strong growth inhibition towards larvae of S. obliqua. The acetone extract of Vitex negundo was found to exhibit all the activities tested against S. obliqua. Other plants tested, Ajuga remota, Andrographis paniculata and Clerodendrum inermre, were found to have low to moderate effects towards S. obliqua.