Document Type : Original Article
Authors
1
Department of Economic Entomology and Pesticides, Faculty of Agriculture, Cairo University, Giza, Egypt
2
Department of Economic Entomology and Pesticides, Faculty of Agriculture, Cairo University, Giza, Egypt.
3
Central Laboratory of Organic Agriculture, Agricultural Research Centre, Giza, Egypt
4
Plant Protection Research Institute, Agricultural Research Centre, Dokki, Giza, Egypt
Abstract
The insecticidal activities of methanolic extracts of two weedy plants leaves Bidens pilosa L. and Rumex dentatus L. at three different concentrations 3, 5 and 7% were tested against three stored grain pests, Rice weevil Sitophilus oryzae L. Saw-toothed grain beetle Oryzaephilus surinamensis L., and Bean weevil Acanthoscelides obtectus Say, compared to Neem oil as a commercial product at the same concentrations for exposure periods 24, 48, 72 and 96 hrs of treatment under laboratory conditions. Results revealed that different concentrations and exposure periods of the two extracts and Neem oil had significant lethal effects against these tested grain pests. In general, R. dentatus extract was found to be the most toxic against the tested grain pests and caused the highest mortality (100.00%) for the three pests S. oryzae, O. surinamensis and A. obtectus when applied at its highest concentration (7%) for an exposure time of 96 hrs (the highest time), followed by Neem oil 90.0±10.0, 70.00±13.3 and 90.00±2.8%, then B. pilosa extract 75.83±5.8, 79.33±5.46 and 87.50±7.2%, respectively at the same concentration and exposure time, indicating that the obtained mortality percentages were concentration and exposure time-dependent. Finally, these results demonstrate that, R. dentatus extract can be used as a promising pesticide against the three stored products insect pests investigated under this study, and strongly recommended to be used as stored grain protectants in the future.
Keywords
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