Silica based inert dusts are eco-friendly alternatives to control stored grain insect pests due to environmental and health concerns associated with use of synthetic insecticides. A study was conducted to determine the efficacy of filter cake (a silica-based inert dust) on the granary weevil, Sitophilus granarius (L.) and lesser grain borer, Rhyzopertha dominica (F.) in stored wheat. Filter cake dust of ≤0.4 mm particle size was admixed with 500 g of wheat seed to provide nominal rates of 10000, 7500, 5000, and 2500 ppm (mg/kg), while the control treatment consisted of wheat seeds that were untreated. The bioassays were carried out using a liter-sized plastic jars in completely randomized design with three replications. Experiments were maintained at 23.1±1.7oC and 61.0±4.3% relative humidity. Mortality data were collected at 3, 7, and 14 d after treatment. Results indicated that mean mortality rate at 3 d after treatment ranged from 41.3 to 70.0% in S. granarius and 73.3 to 93.3% in R. dominica. Mean mortality of S. granarius adults at 14 d in filter cake treatments was 84.0 to 98.7%, whereas that of R. dominica was 98.3 to 100%. The present results show that filter cake dusts can be used to control these two species in stored wheat. Filter cake has potential in protection of wheat from S. granarius and R. dominica infestations in storage.
