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Updated: Jun 27, 2026
06:58
High-Throughput Assays of Critical Thermal Limits in Insects
Published on: June 15, 2020
Temperature as a toxicity identification evaluation tool for pyrethroid insecticides: toxicokinetic confirmation.
Amanda D Harwood1, Jing You, Michael J Lydy
1Fisheries and Illinois Aquaculture Center and Department of Zoology, Southern Illinois University, Carbondale, Illinois 62901, USA.
Environmental Toxicology and Chemistry
|December 17, 2008
Summary
Lower temperatures increase pyrethroid and DDT insecticide toxicity by affecting accumulation and nerve sensitivity, while decreasing chlorpyrifos toxicity through reduced biotransformation. Temperature influences insecticide toxicity mechanisms in aquatic environments.
Area of Science:
- Environmental toxicology
- Ecotoxicology
- Chemical risk assessment
Background:
- Toxicity Identification Evaluation (TIE) methods are crucial for identifying environmental toxicants.
- Established TIE methods are limited for specific contaminant classes, particularly insecticides like pyrethroids.
- Pesticides, especially pyrethroids, are increasingly recognized as significant contaminants in agricultural waters.
Purpose of the Study:
- To validate a temperature-dependent Toxicity Identification Evaluation (TIE) model.
- To elucidate the mechanistic basis for temperature's influence on insecticide toxicity.
- To investigate the toxicokinetics of different insecticide classes across varying temperatures.
Main Methods:
- Comparative toxicity assessments of four insecticides (two pyrethroids, one organophosphate, one organochlorine) on Chironomus dilutus.
- Exposure of organisms to insecticides at two different temperatures (13°C and 23°C).
- Analysis of toxicokinetic parameters, including biotransformation and nerve sensitivity, to explain observed toxicity changes.
Main Results:
- A 10°C decrease in temperature significantly altered insecticide toxicity: pyrethroids and DDT toxicity increased, while chlorpyrifos toxicity decreased.
- Reduced chlorpyrifos toxicity at lower temperatures was linked to decreased biotransformation, forming fewer toxic metabolites.
- Increased DDT toxicity was attributed to heightened nerve sensitivity at 13°C compared to 23°C.
- Pyrethroid toxicity changes resulted from combined effects of increased parent compound accumulation and enhanced nerve sensitivity at lower temperatures.
- Observed trends in water-only exposures were consistent with sediment exposures for chlorpyrifos and permethrin.
Conclusions:
- Temperature is a critical factor influencing the toxicity and toxicokinetics of insecticides.
- The validated temperature TIE model provides mechanistic insights into insecticide toxicity.
- Water-only exposures can adequately represent mechanisms observed in sediment exposures for certain insecticides, simplifying future TIE studies.
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