Screening of weeds for insecticidal properties against rice weevil, sitophilus oryzae

Weeds in nature is usually troublesome however some weeds have excellent potential for using as bio-insecticides. Ten local weeds species namely Ageratum conyzoides, Cleome viscosa, Cymbopogon citratus, Euphorbia hirta, Cyperus iria, Lantana camara, Melastoma malabathricum, Metha sp, Mimosa pudica and Tridax procumbens were selected and screened for its insecticidal activity against Sitophilus oryzae. Selected weed were subjected to absolute ethanol solvent and tested against Sitophilus oryzae to know the lethal or repellent effect. 12% concentration of weed extract was used at the rate of 2 ml with 20 g of rice grain in petri dish with the presence of 20 adult rice weevil. Euphorbia hirta extract showed the highest mortality percentage which is 33%. The weed could be used for further study to isolate the chemical responsible for insect killing