In laboratory tests granulated malathion gave 99% control of larvae of Tendipes plumosus (L.) at 0.1 pound technical per acre in 1 foot of water. At depths greater than 1 foot, some dispersion of malathion often occurred, reducing its effectiveness. Variations in the type, size, or malathion concentration of granules did not appreciably after their effect on T. plumosus. Mud depths greater than 2½ inches did not reduce the effectiveness of malathion granules. In mud and water at approximately pH 7.2, a 50% deactivation of granulated malathion occurred after 4 to 8 days. Snails and leeches appeared to be unaffected by 0.1 pound per acre concentrations of malathion. The leech Helobdella stagnalis (L.) and a protozoan of the genus Thelohania caused considerable mortality in larvae of T. plumosus. Field tests in a 19-acre, 20-foot deep lake failed to control Tendipes larvae at rates as high as 0.8 pound of malathion acre. Lack of control in this lake was attributed to binding of the malathion by organic matter, a species of Tendipes larvae less susceptible to malathion, and dispersion. On a 1-acre test area in Lake Winnebago, a 137,708-acre lake with a maximum depth of 22 feet, granulated malathion applied at 2.0 pounds technical per acre gave about 70% control of larvae of T. plumosns. In adequate control of larvae in this test was considered to be the result of dispersion. After release from the granules, malathion was probably distributed throughout the waters of the lake by wind-created currents.
Document Type: Research Article
Publication date: February 1, 1962
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Journal of Economic Entomology is published bimonthly in February, April, June, August, October, and December. The journal publishes articles on the economic significance of insects and is divided into the following sections: apiculture & social insects; arthropods in relation to plant disease; forum; insecticide resistance and resistance management; ecotoxicology; biological and microbial control; ecology and behavior; sampling and biostatistics; household and structural insects; medical entomology; molecular entomology; veterinary entomology; forest entomology; horticultural entomology; field and forage crops, and small grains; stored-product; commodity treatment and quarantine entomology; and plant resistance. In addition to research papers, Journal of Economic Entomology publishes Letters to the Editor, interpretive articles in a Forum section, Short Communications, Rapid Communications, and Book Reviews.