author(s)
Dr. N Sambasiva Rao

abstract
Efficacy of Spinosad 45 SC, Abamectin 1.8 EC and Emamectin Benzoate 5 SG along with other insecticides was evaluated to access acute and persistant toxicity against lesser grain borer, Rhyzopertha dominica (F.) as surface and jute treatment. After 5 days of treatment on jute surface, 100% mortality of released adults were recorded in Malathion 50 EC @ 150 mg a.i/m2, Deltamethrin 2.5 WP @ 30 mg a.i/m2, Spinosad 45 SC @ 5 mg a.i/m2 and Emamectin benzoate 5 SG @ 4 mg a.i/m2 treatments. Dichlorvas 76 EC @ 150 mg a.i/m2 has produced 98.70% mortality, Abamectin 1.8 EC has produced only 92.31% mortality in adult insects and least effective among the insecticides tested. At 120 days after treatment (120 DAT) Deltamethrin 2.5 WP @ 30 mg a.i/m2 has produced 97.5% mortality of released adults followed by Spinosad 45 SC @ 5 mg a.i/m2 (95.0%) and Emamectin benzoate 5 SG @ 4 mg a.i/m2 (95.0%) are equally effective. The persistence of Malathion 50 EC 150 mg a.i/m2 and Dichlorvas 76 EC 150 mg a.i/m2 has reduced still further when compared to 90 DAT and recorded mortalities of 30.0 and 17.5%, respectively. Least persistence (15.0% mortality) was observed in Abamectin 1.8 EC @ 5 mg a.i/m2 which is equal to control mortality.