ABSTRACT

Laboratory studies were conducted in the Entomology Laboratory of Crop Protection Department, Institute for Agricultural Research, Ahmadu Bello University, Samaru-Zaria, to evaluate the efficacies of four silica-based dust namely; Diatomaceous earth (DE), Periwinkle shell dust (PSD), Rice husk ash (RHAC), and Prawn shellash (PSA) with Pirimiphos methyl (Actellic EC) as the standard check and untreated control (which had no treatment at all) for the management of Triboliumcastaneum(Herbst) on stored wheat. The treatments were laid out in a completely randomized design (CRD) at five concentrations (0.25, 0.50, 1.00, 1.50 and 2.00g/100g of wheat grains) each repeated three times. The parameters assessed for the efficacy of the silica based dust include; adult mortality at 24, 48 and 72 hours post treatment; progeny emergence (F1 and F2), and percentage grain damage. Results obtained sowed that DE applied at 1.00and 2.00 g/100 g had hundred percent mortality. PSA had 93 % adult insect mortality, which was not significant difference from the standard check (Actellic EC).RHC and PS together with the untreated check had the least number of adult insect mortalityand were not significantly different. F1 and F2 progeny emergence was inhibited in all the treatments except the untreated check. At 40 days post-treatment (F1) progeny emergence was completely (100%) suppressed by the standard check followed by PSD (0.33), DE (1.00), RHAC (1.47) and PS had the least control of progeny (6.13). At 80 days, F2 progeny emergence showed that RHC had least mean number of emergence (0.067), followed by DE (0.20), PSD (1.33) and PS (5.33). There was no significant difference between PSD, DE and RHAC with the standard check in terms of preventing grain damage. PSD, DE and RHAC treated wheat grains had the least grain damage which were similar to the standard check. Wheat grains treated with PS suffered the highest grain damage which was similar to the untreated check. DE was the best among the silica-based dust followed by PSD, then RHAC in the control of T.castaneum, while PS had the least control. Therefore, DE, PSD and RHAC can be recommended for use as grain protectant.