Persistence and Efficacy of Spinosad, Indoxacarb and Deltamethrin against Major Insect Pests of Stored Wheat

Insecticidal effectiveness and degradation of spinosad 45 SC and indoxacarb 15 SC applied @ 0.5, 1.0 and 3.0 mg a.i. kg⁻¹ and deltamethrin 2.8 EC @ 3.92 mg a.i. kg⁻¹ on wheat in laboratory against adults of Rhizopertha dominica, Sitophilus oryzae and Trogoderma granarium are reported. Treated wheat was kept at 20 to 30°C and 65 to 75% RH. Wheat treated with spinosad @ 1.0 and 3.0 mg a.i. kg⁻¹ recorded 100 per cent adult mortality against R. dominica up to 120 days of storage. In case of S. oryzae, 100 per cent mortality was observed up to 90 and 30 days @ 3.0 and 1.0 mg a.i. kg⁻¹ respectively. Wheat treated with deltamethrin recorded 100 per cent mortality of R. dominica, S. oryzae and T. granarium up to 15 days of storage which declined gradually thereafter, and at 120 days failed to cause any mortality. Spinosad and indoxacarb residues persisted for more than 120 days but deltamethrin residues persisted up to 90 days only. Half lives of spinosad, indoxacarb and deltamethrin were 43 to 51.02, 23.33 to 31.68 and 15.28 days, respectively.