Residual toxicity and effectiveness of seven insecticides for sack treatment in protecting corn and milled rice from insect damage in the warehouse [Philippines]
1987
Sia, M.A. | Rejesus, B.M.
The residual toxicity and effectiveness of four synthetic pyrethroids (deltamethrin, cypermethrin, permethrin and fenvalerate) and three organophosphates (pirimiphos-methyl, metacrifos and malathion) for sack treatment were determined under laboratory and warehouse conditions. Laboratory evaluation indicated that six insecticides were residually more toxic than malathion to the corn weevil (Sitophilus zeamais Mostsch.), lesser grain borer (Rhyzopertha dominica Fabr.) and red flour beetle (Tribolium castaneum Herbst.). Insecticides applied by impregnation were residually more toxic than sprayed. The insects found in the warehouse during the study were corn weevil, red flour beetle, flat grain beetle (Cryptolestes ferrugineus [Stephens]) and foreign grain beetle (Ahasverus advena Walt.). A predatory anthocorid bug (Xylocoris sp.) and an unidentified parasite were also noted. Based on the population build-up and damage, all were effective in treating bags for storage of corn and milled rice in the warehouse for at least six months. Malathion gave the least protection among them. Milled rice had lower insect population build-up and damage than the corn stored in treated sacks. The residue level in milled rice and corn stored in sacks treated with 1% deltamethrin, and cypermethrin stored for 90 days and with permethrin stored for 30 days were below the Maximum Residue Limits set by FAO/WHO. Thus, these insecticides can be used as substitute for malathion to protect corn and milled rice against insect damage for six months.
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