studies on the insecticidal effect of spinosad on the adults of tribolium castaneum (herbst), sitophilus oryzae(l.) and oryzaephilus surinamensis(l.) under laboratory conditions

abstract due to economical importance of stored product pests and resistance to conventional insecticides, it is necessary to use novel and suitable compounds in control programs. therefore, we evaluated the toxicity of spinosad to three important storage insect, red flour beetle, tribolium castaneum (herbst), rice weevil, sitophilus oryzae (l.), sawtoothed grain beetle oryzaephilus surinamensis (l.). one-day old adult insects were exposed to different concentrations of spinosad. the exposure times were 1, 10 and 20 d for oral trials. experiments were performed in complete randomized block design with 4 replications. after treatment the samples were held under constant conditions in laboratory rearing room (27±2ºc, 65±5 r.h and 14 d: 10 l photoperiod). for t. castaneum the maximum mortality rate was achieved with 95 ppm of spinosad after 10 d. application of 80 ppm spinosad after 10 days caused maximum mortality rate in s. oryzae. the complete control of o. surinamensis was occurred with 150 ppm during 20d, the required concentrations for complete cessation of adult emergence were 95, 80 and 150 ppm of spinosad for t. castaneum, s. oryzae and o. surinamensis, respectively.