Efficacy of three plant species extracts in the control of Trogoderma granarium Everts (Coleoptera: Dermestidae).

摘要

Toxicity of aqueous, methanolic and acetone extracts of three plant species, Ruta chalepensis, Withania somnifera and Cassia senna, to the khapra beetle, Trogoderma granarium Everts, larvae reared on treated wheat seeds were investigated in the laboratory. All extracts showed remarkable toxicities but to varying extents, the greatest toxicity being due to acetonic extracts. Of the three species, the acetonic extract of R. chalepensis showed a relatively more pronounced toxic effect, having an acute (2-day) and chronic (6-day) lethal concentration to half of tested insects (LC_50s) of 391 and 214 ppm compared to 467 and 251 ppm for Withania somnifera and 576 and 317 ppm for C. senna, respectively. The toxic effect was found to be dose and exposure-time dependent. The toxicity of acetonic extracts was found to be about 1.4 fold of that observed for either aqueous or methanolic extracts, throughout all concentrations employed. These materials could have promising practical application in protection of stored grains against attack by T. granarium.