Persistence and Effectiveness of Diatomaceous Earth and Spinosad® Against Sitophilus zeamais (Coleoptera: Curculionidae) on Stored Rice

The insecticidal and residual effectiveness of Diatomaceous Earth (DE) (Nigeria-derived) and Spinosad® against Sitophilus zeamais on stored rice were evaluated under laboratory temperature (30 ± 2°C) and relative humidity (70 ± 5%). Adult mortality and progeny emergence were studied at three dose rates of DE and Spinosad® (0.1g/kg, 0.5g/kg, and 1g/kg). Spinosad® at 0.1-1.0 g/kg dose rates demonstrated significant results in mortality compared to DE and control groups at 14 d post-treatment and after the 2nd month of storage treatment. Spinosad® treated grains at the same dose rates also resulted in a significant reduction (P<0.05) in the emergence of progeny. Unlike DE, Spinosad® showed some insecticidal efficacy against S. zeamais on storage.