Efficacy of Unsynergised Deltamethrin and Deltamethrin + Chlorpyrifos-methyl Combinations as Protectants of Stored Wheat and Stored Corn (Maize)*

Soft red winter wbeat and “Pioneer 3324” corn (maize) were treated witb either 0.5, 0.75, 1.0 ppm deltamethrin, 0.5 ppm deltamethrin + 6.0 ppm chiorpyrifo!+metbyI, 1.0 ppm deItamethrIn + 6.0 ppm chhpyrifos-methyl, or 6.0 ppm cbIorpyrifos-methyl, and subsequentIy stored for 10 months. Bioasays were conducted every 2 moaths during this storage period. R&o*ha dominica (F.) and SiZophilus oryx (L.) did not survive on the combIn8tio11 treatments appIIed to wheat. Survival of R. ahhica in the three deitametbh treatments was variable throughout the storage period but no F, adults were detected. S. oryzoc survIvaI on wheat treated witb 0.5 ppm dehnethrin ranged from 0 to 84.5%. Maximum survivaI In the 0.75 and 1.0 ppm dehmetbrin treatments was 26.2 and 3.5%, respecthely. Sitophifns zeamais (Motsch.) or Tribolium castamwm (Herb&) did oat survive in the combiition treatments applied to corn. Maximum S. zeumuis sod R. castaneum survival in the. three dehnehin treatments was 23.5 and 18.7%, respectively, but there were w sigoilicaot trends during storage aud F, productioo was minimal. Key wordr-Grain, storage, protectants, pyrethroids, beetles.