Toxicity of the Mosquito Control Pesticide Scourge® to Adult and Larval Grass Shrimp (Palaemonetes pugio)

Abstract

This study investigated the toxicity of various concentrations of technical resmethrin and Scourge® on adult and larval Palaemonetes pugio, a common grass shrimp species. Two types of tests were conducted for each of the resmethrin formulations using adult and larval grass shrimp life stages, a 96-h static renewal aqueous test without sediment, and a 24-h static nonrenewal aqueous test with sediment. For resmethrin, the 96-h aqueous LC₅₀ value for adult shrimp was 0.53 μg/L (95% confidence interval (CI): 0.46–0.60 μg/L), and for larval shrimp was 0.35 μg/L (95% CI: 0.28–0.42 μg/L). In the presence of sediment, technical resmethrin produced a 24-h LC₅₀ value for adult shrimp of 5.44 μg/L (95% CI: 4.52–6.55 μg/L), and for larval shrimp of 2.15 μg/L (95% CI: 1.35–3.43 μg/L). For Scourge®, the 96-h aqueous LC₅₀ for adult shrimp was 2.08 μg/L (95% CI: 1.70–2.54 μg/L), and for larval shrimp was 0.36 μg/L (95% CI: 0.24–0.55 μg/L). The 24-h sediment test yielded an LC₅₀ value of 16.12 μg/L (95% CI: 14.79–17.57 μg/L) for adult shrimp, and 14.16 μg/L (95% CI: 12.21–16.43 μg/L) for larvae. Adjusted LC₅₀ values to reflect the 18% resmethrin concentration in Scourge® are 0.37 μg/L (adult), 0.07 μg/L (larvae) for the 96-h aqueous test, and 2.90 μg/L (adult), 2.6 μg/L (larvae) for the 24-h sediment test. Larval grass shrimp were more sensitive to technical resmethrin and Scourge® than the adult life stage. The results also demonstrate that synergized resmethrin is more toxic to P. pugio than the nonsynergized form, and that the presence of sediment decreases the toxicity of both resmethrin and Scourge®     

Uptake of 17β-estradiol and biomarker responses in brown trout (Salmo trutta) exposed to pulses

In streams, chemicals such as 17β-estradiol (E2) are likely to occur in pulses. We investigated uptake and biomarker responses in juvenile brown trout (Salmo trutta) of 3- or 6-h pulses of concentrations up to 370 ng E2 L⁻¹. Uptake by the fish was estimated from disappearance of E2 from tank water. A single 6-h pulse of 370 ng E2 L⁻¹ increased the plasma vitellogenin concentration, liver Erα- and vitellogenin-mRNA. Exposure to 150-160 ng E2 L⁻¹ for 6 h increased vitellogenin in one experiment but not in another. Two 6-h pulses had a larger effect one pulse. Brown trout in the size range 24-74 g took up E2 linearly with time and exposure concentration with a concentration ratio rate of 20.2 h⁻¹. In conclusion, the threshold for induction of estrogenic effects in juvenile brown trout at short term pulse exposure appears to be in the range 150-200 ng E2 L⁻¹.     

Acute exposition to Roundup Transorb® induces systemic oxidative stress and alterations in the expression of newly sequenced genes in silverside fish (Odontesthes humensis)

Environmental Science and Pollution Research - Roundup Transorb® (RDT) is a glyphosate-based herbicide commonly used in agricultural practices worldwide. This herbicide exerts negative effects...