Antifeedant effects of crofton weed, Ageratina adenophora extracts and their phytochemical compounds against three cabbage insect pest species

Abstract

Given that synthetic pesticides used in agricultural fields have negative side effects, safer alternatives such as botanical insecticides are required for insect pest management. Here, solvent extracts (hexane, ethyl acetate, chloroform, acetone, and methanol) of crofton weed, Ageratina adenophora (Spreng.) King & H.Rob. (Asteraceae), were studied for antifeedant activity against third instars of large cabbage white butterfly, Pieris brassicae L. (Pieridae), diamondback moth, Plutella xylostella L. (Plutellidae), and cabbage cluster caterpillar, Crocidolomia pavonana Fabricius (Crambidae, all Lepidoptera). Among the solvent extracts tested, A. adenophora hexane extract at 5% concentration exhibited maximum antifeedant activity against P. xylostella (92.1%), C. pavonana (87.4%), and P. brassicae (81.7%). The effective concentration (EC50) values were 1.4, 2.1, and 2.8%, respectively. The hexane extract was characterised using gas chromatography–mass spectrometry (GC–MS) analysis and it was determined that its main compounds were 9,11-octadecadiynoic acid, 8-oxo-, methyl ester (27.5%), 2(3H)-naphthalenone, 4,4a,5,6,7,8-hexahydro-4a, (R)-7,7-trimethyl- (20.4%), germacrene D (6.1%), 2(1H)-naphthalenone (5.8%), 5,6-decadien-3-yne, 5,7-diethyl (5%), and α-bisabolene (2.1%). The results suggest that hexane extract of A. adenophora could be used for the development of botanical insecticides.