LABORATORY EVALUATION OF ACID-ACTIVATED KAOLIN TO PROTECT STORED PADDY AGAINST INFESTATION BY STORED PRODUCT INSECTS

The toxicity of acid-activated kaolin to adult populations of Sitophilus oryzae, S. zeamais, Tribolium castaneum, Cryptolestes pusillus, Oryzaephilus surinamensis and Rhyzopertha dominica was assessed by admixing the material with paddy and determining mortality at 72 hr. C. pusillus and O. surinamensis were highly susceptible to the desiccant effect, while T. castaneum and the Sitophilus spp were relatively tolerant; the susceptibility of all species to the material decreased as paddy moisture content was increased from 7.2 to 19.2%. A dose of approx. 5 g/kg considerably reduced F1 progeny production of all the above species and of Sitotroga cerealella. Subsequent heat treatment of acid-activated kaolin had no significant effect on either its oil adsorption capacity or its toxicity to the species tested. © 1990.