Biological activities ofTrewia nudiflora extracts against certain economically important insect pests.

An ethanol extract ofTrewia nudiflora (Euphorbiaceae) seed was tested as an agent for controlling several economically important insects. Results suggest that this plant extract acts as an antifeedant for the spotted cucumber beetle (Diabrotica undecimpunctata howardi Barber) and the European corn borer [Ostrinia nubilalis (Hübner)] but not for the other insects tested. Also indicated were morphogenic effects on the codlingmoth [Laspeyresia pomonella (L.)], disruption of the normal life cycle of the redbanded leafroller [Argyrotaenia velutinana (Walker)], and reduction in the progeny of the plum curculio [Conotrachelus nenuphar (Herbst)]. In addition, the extract was toxic to the striped cucumber beetle [Acalymma vittatum (F.)] and gave 100% control of the chicken body louse [Menacanthus stramineus (Nitzsch)] from 5 to 28 days. Fractionation of the extract was monitored by a bioassay usingO. nubilalis. This fractionation yielded six pure compounds, the most abundant of which was trewiasine. Its LD50 was 7.4 ppm when incorporated into the diet ofO. nubilalis. Dose-mortality relationships for the other compounds withO. nubilalis are presented.