cyhalothrin and resmethrin

Pyrethroid insecticides are hydrophobic compounds that partition to streambed sediments and have been shown to cause toxicity to non-target organisms; their occurrence is well documented in parts of California, but there have been limited studies in other urban and agricultural areas across the United States. To broaden geographic understanding of pyrethroid distributions, bed sediment samples were collected and analyzed from 36 streams in 25 states, with about 2/3 of the sites in urban areas and 1/3 in agricultural areas. At least one pyrethroid (of the 14 included in the analysis) was detected in 78% of samples. Seven pyrethroids were detected in one or more samples. Bifenthrin was the most frequently detected (58% of samples), followed by permethrin (31%), resmethrin (17%), and cyfluthrin (14%). The other three detected pyrethroids (cyhalothrin, cypermethrin and delta/tralomethrin) were found in two or fewer of the samples. Concentrations ranged from 0.3 to 180 ng g(-1) dry weight. The number of pyrethroids detected were higher in the urban samples than in the agricultural samples, but the highest concentrations of individual pyrethroids were split between urban and agricultural sites. The pyrethroids detected in the agricultural areas generally followed use patterns. Predicted toxicity was greater for urban areas and attributed to bifenthrin, cyfluthrin and cypermethrin, while in agricultural areas the toxicity was mainly attributed to bifenthrin.

Topics: Agriculture; Cities; Environmental Monitoring; Geologic Sediments; Insecticides; Nitriles; Permethrin; Pyrethrins; Rivers; United States; Water Pollutants, Chemical; Water Pollution, Chemical

Lambda-cyhalothrin was evaluated as an ultralow volume ground adulticide treatment at rates of 0.25, 0.5 and 1.0 g/ha. Resmethrin, a standard adulticide, was applied at a rate of 1.96 g/ha. All treatments provided greater than or equal to 95% control up to 50 m from the spray route. The highest rate of lambda-cyhalothrin and the resmethrin standard provided greater than or equal to 95% control up to 200 m, which is twice the distance normally assessed in this type of testing. Control was reduced at 200 m for the 0.25 and 0.5 g/ha rates of lambda-cyhalothrin, which provided 73 and 88% mortality, respectively. Lambda-cyhalothrin appears to have the insecticidal activity required for operational mosquito control.

Topics: Animals; Anopheles; Arkansas; Insecticides; Mosquito Control; Nitriles; Pyrethrins