Proximal analysis and insecticidal effects of extracts from pepper tree (Schinus molle) leaves on elm leaf beetle (Xanthogaleruca luteola) larvae

Abstract

Among a series of exotic pests that have been reported in Chile, Xanthogaleruca luteola Müller (Coleoptera: Chrysomelidae), a defoliating insect of elms (Ulmus spp.), is causing important damage in urban trees in central Chile. Leaves from Schinus molle L. (Anacardiaceae), an interesting South American plant, were characterized and compared physically and chemically through proximal analysis. Also, the insecticidal effects of ethanol and water extracts from young and mature leaves of S. molle were evaluated on third instar larvae of X. luteola at concentrations of 0.5–4.3% w/v. Water and lipid contents presented the greatest differences in both leaf maturity stages. At 12d, the maximum concentrations obtained with ethanol and water from young and mature leaves caused mean mortalities of 89 and 67, and 78 and 63%, respectively. The lowest 50% lethal concentration was 1.28% w/v, obtained at the 7th day of evaluation with the ethanol extract from young leaves. Hence, extracts from S. molle leaves may have a potential use as a bioinsecticide in Integrated Pest Management plans against X. luteola and other similar pests defoliating urban trees, to decrease the risk of using conventional pesticides in public areas.