Toxicity of fipronil and its degradation products to Procambarus sp.: Field and laboratory studies

• Published in: Archives of environmental contamination and toxicology Vol. 41; no. 3; pp. 325 - 332
• Main Authors: SCHLENK, D, HUGGETT, D. B, ALLGOOD, J, BENNETT, E, RIMOLDI, J, BEELER, A. B, BLOCK, D, HOLDER, A. W, HOVINGA, R, BEDIENT, P
• Format: Journal Article
• Language: English
• Published: Heidelberg Springer-Verlag 01.10.2001; Berlin Springer Nature B.V; New York, NY
• Subjects: Alkalinity; Animal, plant and microbial ecology; Animals; Applied ecology; Astacoidea - drug effects; Astacoidea - physiology; Biological and medical sciences; Degradation products; Ecotoxicology, biological effects of pollution; Effects of pollution and side effects of pesticides on protozoa and invertebrates; Environmental Exposure; Fipronil; Freshwater; Fundamental and applied biological sciences. Psychology; Insecticides; Insecticides - toxicity; Laboratories; Metabolites; Organic sediments; Oryza; Oryza sativa; Pesticides; Ponds; Population Dynamics; Procambarus; Procambarus clarkii; Procambarus zonangulus; Pyrazoles - agonists; Pyrazoles - toxicity; Seeds; Surface water; Toxicity; Water Pollutants, Chemical - toxicity; USA, Louisiana; USA, Arkansas, White R; Laboratory study; Insecticide; Toxicity; Mortality; Pesticides; Macrura; Crustacea; Freshwater environment; Lethal dose 50; Arthropoda; Pyrazole derivatives; Water pollution; Decapoda; Invertebrata; Non target organism; Degradation product; Comparative study; Field study
• ISSN: 0090-4341; 1432-0703
• DOI: 10.1007/s002440010255

Fipronil is a phenylpyrazole insecticide that is the active ingredient in the pesticide Icon 6.2 FS which is applied to rice seeds targeting the rice water weevil. An arthropod-selective insecticide, fipronil blocks the GABA-gated chloride channel and is unique in that several of its degradation products have been indicated to be equal or more potent than fipronil. After application of rice seeds (2-3 days postplant) to flooded rice fields, water is typically pumped from the rice fields and can be used for the culture of crayfish (Procambarus sp.). Because fipronil is selective for arthropods, is transported via organic sediment, and crayfish consume organic sediment, 96-h LC(50) experiments were conducted with fipronil and three of its environmental derivatives in crayfish under conditions without carrier solvents in water of similar pH, alkalinity, and hardness as observed in south Louisiana crayfish culture ponds. Measured LC(50)s for fipronil to red swamp (Procambarus clarkii) and white river (Procambarus zonangulus) crayfish were 14.3 (95% CI; 5.1-23.4) and 19.5 (95% CI; 11.1-27.9) microg/L, respectively. LC(50)s of fipronil sulfone (11.2; 9.2-13.2 microg/L), fipronil sulfide (15.5; 13-18 microg/L); and the photoproduct, desulfinyl fipronil (68.6; 46-95.2 microg/L) displayed very high toxicity in crayfish. In situ toxicity studies using caged crayfish in culturing ponds receiving effluent from drained rice fields indicated that effluent from rice fields planted with Icon-treated seed was significantly more toxic compared to untreated surface water (40% survival compared to 83% survival). Hazard quotient comparisons using measured water concentrations in the field and laboratory-based LC(50)s indicated that fipronil and its metabolites in water resulting from Icon-treated rice seed planting poses a significant risk to crayfish survival.