Cyprinella lutrensis gill lesions after exposure to terbufos

Abstract

Terbufos (O, O-diethyl, S-(((1, 1-dimethylethyl)thio)methyl) phosphorodithioate), purity 98% acts as anticholinestrase. Commercial formulations are applied to soil as an insecticide-nematicide throughout the United States to control com root-worm larvae and other pests, preventing an economical loss to producers Terbufos is highly toxic to fish species (e.g., fathead minnows 96 hr's LC50 is 150 μg L−1) and toxicity increases as temperature increase. There have been no reports on its effects on fish gills.Red shiners (Cyprinella lutrensis) were collected from the Platte River, Nebraska using a seine and maintained in 30-L glass aquaria (10 fish /tank) for a 14-d acclimation period at 22°C on a 12:12 photoperiod and fed a commercial fish food once daily except for 24-h before and at the beginning of bioassays. During the 14-d bioassay, fish were exposed to terbufos concentrations of 0, 1, 10, and 100μg L−1. At the conclusion of the bioassay, fish were fixed in 3% glutaraldehyde with 0.1 M phosphate buffer. Gills were removed, washed in 0.1 M phosphate buffer and post-fixed in 1% OsO4 for 2-h, gills were rinsed in water and dehydrated in a graded ethanol series. After critical point drying using liquid CO2, gill tissues were mounted on stubs, coated with gold-palladium and examined using a Cambridge S-90 stereoscan at 15 kV