Abstract
Farmers stock peanuts were treated with pirimiphosmethyl (0- [2- (diethvlamino)-6-methyl-4-pyrimidinyl 0,0-dimethyl phosphorothioate) applied at rates of 10, 20, and 30 ppm as a protectant against stored-product insects and stored in metal bins (4.5 metric tons) for 1 year. Similar peanuts were treated with malathion (diethyl mercaptosuccinate S-ester with 0,0-dimethyl phosphorodithioate) applied at a rate of 52.1 ppm as a standard for comparison. Although residues of pirimiphos-methyl decreased ca. 63% during the year (half of the decrease during the first 4 months), rates of 20 and 30 ppm gave excellent protection for 1 year, and a rate of 10 ppm gave protection for about 6 months. Malathion was relatively ineffective, either because it degraded so rapidly the first 2 months or because malathion-resistant strains of insects were present.
Of the 16 species of stored-product insects found in the peanuts, red flour beetles, Tribolium castaneum (Herbst), and almond moths, Cadra cautella (Walker), were the predominant species.
Author notes
1This paper reports the results of research only. Mention of a pesticide in this paper does not constitute a recommendation for use by the U.S. Department of Agriculture nor does it imply registration under FIFRA as amended. Also, mention of a commercial or a proprietary product in this paper does not constitute an endorsement for use by the U.S. Department of Agriculture.
3The Peanut Insect Investigations is now a part of the Stored-Product Insects Research and Development Laboratory, Savannah, Ga.