T9 PM Pyrethroid Insecticides in Urban and Agricultural Environments
Tuesday, 15 November 2005: 1:50 PM - 5:30 PM in 339-340

(DEL-1117-565334) Toxicity of the pyrethroid insecticide permethrin to adult and larval grass shrimp (Palaemonetes pugio).

DeLorenzo, M^{1, 3}, Serrano, L^{2, 3}, Hoguet, J³, Chung, K³, Key, P³, ¹ University of South Carolina, Columbia, SC, USA³ NOAA, National Ocean Service, Charleston, SC, USA² College of Charleston, Grice Marine Biology Program, Charleston, SC, USA

ABSTRACT- The use of pyrethroid insecticides is increasing as these compounds are replacing organophosphates in agricultural and urban settings. Along the southeast coast of the U.S., pyrethroids are commonly used for mosquito control, agricultural crop protection, and home pest control; resulting in significant potential for contamination of the estuarine environment. Synthetic pyrethroids are neurotoxins, affecting both target and nontarget organisms. Toxicity of the pyrethroid insecticide permethrin was assessed using three life stages of the estuarine grass shrimp, Palaemonetes pugio. Adult and larval shrimp were tested using a 96-hour static renewal aqueous test without sediment, and a 24-hour static nonrenewal aqueous test with sediment. For the embryos a 96-hour static renewal aqueous test without sediment was conducted. Two cellular stress biomarkers, glutathione and lipid peroxidation, were also assessed using the adult and larval life stages. Larval shrimp were more sensitive than adults, with a 96h LC50 value of 0.05 g/L (95% confidence interval (CI) of 0.04-0.05 g/L), compared to 0.25 g/L (95% CI: 0.21-0.31) for adults. Grass shrimp embryos were least sensitive to permethrin, with a 96h LC50 value of 3.70g/L. Permethrin exposure increased the time to hatch in embryos, although a dose-response relationship with concentration was not observed. Changes in swimming behavior were observed at the highest concentration for newly hatched larvae in the embryo test (6.4 g/L), and for larvae in the aqueous larval toxicity test (0.2 g/L). Glutathione levels increased with permethrin exposure, while lipid peroxidation values decreased. The presence of sediment significantly decreased the toxicity of permethrin to both adult and larval grass shrimp. These results indicate that very low levels of permethrin may negatively affect individual grass shrimp health and survival. Permethrin use in the coastal zone should be carefully managed to avoid adverse impacts on non-target estuarine organisms.

Key words: pyrethroid, estuarine, grass shrimp, biomarkers