Joint acute toxicity of esfenvalerate and diazinon to larval fathead minnows (Pimephales promelas)

Debra L. Denton, Craig E. Wheelock, Shauna A. Murray, Linda A. Deanovic, Bruce D. Hammock, David E. Hinton

Research output: Contribution to journalArticlepeer-review

75 Scopus citations


California (USA) agriculture employs pyrethroid and organophosphate insecticides to control insects in orchards and other crops. Diazinon and esfenvalerate were selected for this study because of their application overlaps. Toxicological and biochemical responses of larval fathead minnows (Pimephales promelas) exposed singly and in combinations to esfenvalerate and diazinon were determined. Exposures were 96-h static renewal tests that used standard U.S. Environmental Protection Agency acute toxicity test methods. After pesticide exposures, larvae were evaluated for carboxylesterase and acetylcholinesterase activity, and histopathological effects. Carboxylesterase activity was examined because of its potential influence on the toxicity of both organophosphates and pyrethroids. In vivo studies demonstrated that diazinon significantly inhibited carboxylesterase activity at nominal water concentrations as low as 50 μg/L. However, esfenvalerate did not affect carboxylesterase activity at any concentration tested. Liver glycogen depletion was the only histopathological effect observed; this effect was demonstrated with the individual pesticides and pesticide combinations (i.e., mixtures). The combinations of diazinon and esfenvalerate causing acute toxicity to fathead minnow larvae appeared to be greater than additive (i.e., synergistic) in all three tests.

Original languageEnglish (US)
Pages (from-to)336-341
Number of pages6
JournalEnvironmental Toxicology and Chemistry
Issue number2
StatePublished - Feb 1 2003


  • Carboxylesterase activity
  • Diazinon
  • Esfenvalerate
  • Pesticide interactions
  • Synergistic effect

ASJC Scopus subject areas

  • Environmental Science(all)
  • Environmental Chemistry
  • Toxicology
  • Health, Toxicology and Mutagenesis


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