Insecticide treatments used against a rice bloodworm, Chironomus tepperi (Diptera: Chironomidae): toxicity and residual effects in water
1991
Stevens, M.M.
The toxicity and persistence in water of six organophosphate insecticide treatments used for control of Chironomus tepperi Skuse was evaluated. Each insecticide was applied to three rice bays (20 by 4 m) at the maximum recommended field rate. Fourth-instar C. tepperi were tested with water samples taken at various intervals after insecticide application. All treatments caused high (>97%) initial mortality of larvae with the exception of diazinon (0.13 ppm; average initial mortality, 47.3%). Temephos (0.06 ppm) showed the least residual activity, with no mortality occurring 5 d after application. Chlorfenvinphos (0.27 ppm) had the longest residual effect in water, resulting in 61.5% mortality 15 d after application but only nominal activity at 20 d. The remaining treatments, diazinon, chlorpyrifos (0.08 ppm), trichlorfon (0.47 ppm), and malathion (0.32 ppm), provided <10% mortality after 7 d.
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