Efficacy and safety of some plant extracts as alternatives for sitophilus oryzae control in rice grains

Abstract

The rice weevil (Sitophilus oryzae) is a serious stored product pest which attacks several economically important crops. In an attempt to find alternative to control this insect, extracts of seven plant species (Bauhinia purpurea, Caesalpinia gilliesii, Cassia fistula, Cassia senna, Chrysanthemum frutescens, Euonymus japonicus and Thespesia populnea acutiloba) were evaluated under laboratory conditions for their ability to protect rice grains against Sitophilus oryzae insect. The efficacy of the tested plant extracts was evaluated on whole rice grains with respect to mortality and emergency of S. oryzae adults. Moreover, gas chromatography-mass spectrometry (GC-MS) analysis was carried to identify the chemical components of the most effective plant extract against S. oryzae. Furthermore, the safety of the most effective plant extract was evaluated with respect to biochemical and histological changes in treated rats relative to control. The results revealed that, the tested botanical extracts showed high efficiency against S. oryzae and C. gilliesii extract was the most effective plant extract against S. oryzae. The GC-MS analysis showed the presence of different bioactive chemical components that known by its insecticidal activity. The most effective plant extract showed low toxicity on rats relative to control with respect to biochemical and histological changes. The results suggest the ability of using these plant extracts in rice grains protection as a safe alternative to insecticides. Moreover, the presence of mixture of components with, apparently, different mechanisms of insecticidal activity of the tested plant extracts may be delay the resistance development by insect relative to the insecticide. © © 2012 Academic Journals Inc.