Stream microcosm toxicity tests: Predicting the effects of fenvalerate on riffle insect communities

Abstract

Stream microcosms were used to predict toxicity of the pyrethroid insecticide fenvalerate to riffle insect assemblages. Over a 30‐d test period, stream microcosms were exposed in triplicate to 0.0, 0.01, 0.1, 1.0, or 10.0 μg/L fenvalerate. Effects were determined by statistically comparing insect abundances over all concentrations. Initial exposure resulted in a significant increase in drift in the 1.0‐ and 10.0‐μg/L treatments. After 30 d, several taxa exhibited density reductions at 0.01 μg/L, but this reduction was significant for only one taxon. Densities of most other taxa decreased significantly at 0.1 μ/L. Significant reductions in species richness and total density also were observed at 0.1 μg/L fenvalerate. Overall, the results suggest that at environmental concentrations of 0.1 μg/L, mayflies and stoneflies would be eliminated and riffle beetles, caddisflies, and some chironomids would be present in significantly reduced numbers.

Macroinvertebrate community response to pulse exposure with the insecticide lambda‐cyhalothrin using in‐stream mesocosms

“…The idea that stream macroinvertebrate communities are highly resilient to single pulses of insecticides is supported by the findings of Sibley et al [10], who exposed a Canadian headwater stream to a single, 15-min pulse exposure (16 g L Ϫ1 ) of the pyrethroid permethrin. However, several repeated exposures [29] or prolonged exposure [30] might exclude species for as long as 18 months after exposure, as observed by Kreutzweiser and Kingsbury [29]. However, several repeated exposures [29] or prolonged exposure [30] might exclude species for as long as 18 months after exposure, as observed by Kreutzweiser and Kingsbury [29].…”

A combined microcosm and field approach to evaluate the aquatic toxicity of azinphosmethyl to stream communities

“…In order to reduce uncertainties when extrapolating from experimental studies to the field, multispecies tests have been developed [5]. Thus, Breneman and Pontasch [6] exposed insect communities in stream microcosms for a period of 30 d to fenvalerate. They found significant reductions of many insect taxa at levels of 0.1 μg/L; however, the field relevance of fenvalerate exposure over such long time periods is restricted.…”

Runoff simulation with particle‐bound fenvalerate in multispecies stream microcosms: Importance of biological interactions

“…The exposed test organisms increased their downstream drift as an acute response to FV runoff simulation. Drift of macroinvertebrates is a known response to experimental py‐rethroid exposure, but in all the reports concerning FV so far, the pesticide was present only in dissolved form [11,18]. The fact that the organisms drifted at levels as low as 13.6 μg/kg indicates that the FV is bioavailable and capable of inducing increased drift behavior.…”

“…As a result, multispecies tests have been developed to reduce uncertainties when extrapolating from the laboratory to the field [9,10]. To predict the effects of FV on riffle insect communities, Breneman and Pon‐tasch [11] exposed stream microcosms for a period of 30 d to aqueous concentrations between 0.01 and 10 μg/L. They found significant reductions of many insect taxa at levels of 0.1 μg/L; however, the field relevance of FV exposure over such long time periods is restricted.…”