A COMPARISON OF MALATHION DIAZINON FENITROTHION AND DICHLORVOS FOR CONTROL OF SITOPHILUS ORYZAE (L) AND RHYZOPERTHA DOMINICA (F) IN WHEAT

Responses of Sitophilus oryzae (L.) and Rhyzopertha dominica (F.) were established for exposure to filter paper impregnated with malathion, diazinon, fenitrothion or dichlorvos, and of mixtures of dichlorvos with the other materials. Significant changes in toxicity of mixtures were recorded with both species. The acute and residual toxicity of the four materials and of the mixtures were checked under laboratory conditions over a range of moisture contents from 11 to 13 per cent. Comparisons then were made under bulk storage conditions. Fenitrothion was the most promising material. Treatment of immature stages with the four materials showed that malathion was effective only against newly hatched larvae of S. oryzae and the free living stages of R. dominica. The activity of the other materials against later stage larvae and unemerged adults was dichlorvos>fenitrothion>diazinon. The materials were not effective against mature larvae and pupae. © 1968.