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CC BY-NC V4.0, Open Access
Thesis
CHLORANTRANILIPROLE AND CYANTRANILIPROLE TOXICITY TO THE FRESHWATER STANDARD SURROGATE SPECIES DAPHNIA MAGNA AND A NATIVE CLADOCERAN, SIMOCEPHALUS VETULUS
Washington State University
Master of Science (MS), Washington State University
05/2025
DOI:
https://doi.org/10.7273/000007366
Abstract
As new pesticides come to market, there is a need to assess their toxicity to nontarget organisms. Companies screen them for toxicity to various organisms before they can be registered by the United States Environmental Protection Agency (USEPA) for sale. The cladoceran Daphnia magna is often used in toxicity tests as a standard surrogate species representing all freshwater invertebrates. However, the use of surrogate species can be problematic if the species is nonnative to the region and less sensitive than the organisms it represents. Differences in susceptibility to pesticides among both aquatic and terrestrial species have been reported, suggesting that the current method of screening is not protective of all species that may be exposed to pesticides. In chapter one, the objective of the study was to investigate the acute and chronic toxicity of two anthranilic diamide class ryanodine-receptor modulator insecticides, chlorantraniliprole (CHLOR, as the formulated product Altacor®) and cyantraniliprole (CYAN, as the formulated product Verimark®), to two species of Daphniids: the standard surrogate species D. magna and a native species Simocephalus vetulus collected and cultured from a local pond in Puyallup, WA, USA. Although I hypothesized S. vetulus would have lower LC50 and EC50 values compared to D. magna, I found no statistically significant difference in their acute lethal toxicities and found D. magna was more sensitive to CHLOR than S. vetulus when looking at immobility as an endpoint. In chronic toxicity tests, I found CHLOR and CYAN significantly decreased fecundity in S. vetulus and the resulting NOEC and LOEC values were lower compared to published D. magna results. In addition to the toxicity tests, the second chapter includes a complete cohort life table for S. vetulus. Vital rates calculated include net reproductive rate (R0) = 232.47, generation time (T) = 23.84, and finite rate of increase (λ) = 1.257. These vital rates resulted in a significantly lower population trajectory compared to D. magna indicating that S. vetulus is inherently more susceptible to stress than D. magna. Life tables can be used to refine population modeling and risk assessments for aquatic invertebrates and food web interactions with predators like endangered salmonids in the Pacific Northwest, USA. Better understanding of differing species susceptibility to new insecticides can guide regulators to improve their screening methods and prevent the registration and/or use of pesticides that unintentionally harm the environment.
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Details
- Title
- CHLORANTRANILIPROLE AND CYANTRANILIPROLE TOXICITY TO THE FRESHWATER STANDARD SURROGATE SPECIES DAPHNIA MAGNA AND A NATIVE CLADOCERAN, SIMOCEPHALUS VETULUS
- Creators
- Stephanie M. Eckard
- Contributors
- John D Stark (Chair)Jenifer McIntyre (Committee Member)Allan Felsot (Committee Member)
- Awarding Institution
- Washington State University
- Academic Unit
- Department of Entomology
- Theses and Dissertations
- Master of Science (MS), Washington State University
- Publisher
- Washington State University
- Number of pages
- 52
- Identifiers
- 99901220323901842
- Language
- English
- Resource Type
- Thesis