Date of Award

1982

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Abstract

In laboratory studies, 24 hr LC(,50) values obtained for Ambush('(REGTM)) and Pydrin('(REGTM)) on 18-27 mm juvenile red swamp crawfish, Procambarus clarkii (Girard), in clear water were 0.49 and 0.37 ppb, respectively. LC(,50) values derived for 10-20 mm channel catfish fry, Ictaluras punctatus Rafinesque, were 1.81 and 1.83 ppb, respectively for Ambush('(REGTM)) and Pydrin('(REGTM)). The addition of alluvial soils to test waters had no apparent effect on toxicity to crawfish but did reduce toxicity to channel catfish. This was attributed to a strong adsorption to clay and organic components of the soils. Applications of field rates of Ambush('(REGTM)) and Pydrin('(REGTM)) to earthen ponds containing caged adult crawfish resulted in nearly total mortality. However, mortality was nominal 7-10 days posttreatment. Tissue residue analyses of crawfish surviving the applications indicated that they do not readily accumulate pyrethroid residues. In a separate pond study, mortality of 0.5 kg channel catfish was unaffected by similar applications of Ambush('(REGTM)) and Pydrin('(REGTM)). The catfish did accumulate pyrethroid residues in the muscle and visceral tissue. However, none of the residues exceeded the F.D.A. established or proposed tolerances. Permethrin and fenvalerate residues were not detectable in fish collected in the fall of the year from several agricultural watersheds. In both pond studies, permethrin residues in pond water became undetectable 7-9 days posttreatment. Fenvalerate residues in water acted similarly, but in one of the studies were still present at low levels 14 days posttreatment. Both pyrethroids were highly attracted to sedimentary materials. This was evidenced by relatively high residues in bottom sediments 24 hr posttreatment. Sediment residues were much more persistent than those in water, but were less than 10 ppb 14 days posttreatment. Both water and sediment residues followed exponential patterns of decay. Calculated half-lives for permethrin ranged from 1.9 to 13.6 days in water and 6.3 to 14.6 days in bottom sediment, depending on application rate. Fenvalerate half-lives ranged from 1.9 to 5.8 days in water and 3.2 to 8.5 days in sediments.

Pages

112

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