title: Comparative and combined acute toxicity of butachlor, imidacloprid and chlorpyrifos on earthworm, Eisenia fetida.
abstract: Various pesticides have become widespread contaminants of soils due to their large applications in agriculture and homes. An earthworm assay was used to assess the acute toxicity of butachlor, imidacloprid and chlorpyrifos with different modes of action. Ecotoxicities of these pesticides were compared for earthworm Eisenia fetida separately and in combination in artificial soil and contact filter paper tests. Imidacloprid was the most toxic for E. fetida with LC₅₀ (lethal concentration 50) values three orders magnitude lower than that of butachlor and chlorpyrifos in both tests. The toxicity of the mixtures was compared to that predicted by the concentration addition (CA) model. According to the CA model, the observed toxicities of all binary mixtures were less than additive. However, for all the mixtures in 14 d artificial soil test, and mixtures of butachlor plus chlorpyrifos and imidacloprid plus chlorpyrifos in 48 h contact filter paper test, the difference in toxicity was less than 30%, hence it was concluded that the mixtures conformed to CA. The combined effects of the pesticides in contact filter paper tests were not consistent with the results in artificial soil toxicity tests, which may be associated with the interaction of soil salts with the pesticides. The CA model provides estimates of mixture toxicity that did not markedly underestimate the measured toxicity, and therefore the CA model is the most suitable to use in ecological risk assessments of the pesticides.
authors.affiliation: Key Laboratory of Agro-Product Quality and Safety of Ministry of Agriculture, Institute of Quality Standards and Testing Technology for Agro-Products, Chinese Academy of Agricultural Sciences, Beijing 100081, China.
authors.forename: Chen
authors.initials: C
authors.lastname: Chen
authors.affiliation: State Key Laboratory Breeding Base for Zhejiang Sustainable Pest and Disease Control/Key Laboratory for Pesticide Residue Detection of Ministry of Agriculture, Institute of Quality and Standard for Agro-Products, Zhejiang Academy of Agricultural Sciences, Hangzhou 310021, China.
authors.forename: Yanhua
authors.initials: Y
authors.lastname: Wang
authors.affiliation: State Key Laboratory Breeding Base for Zhejiang Sustainable Pest and Disease Control/Key Laboratory for Pesticide Residue Detection of Ministry of Agriculture, Institute of Quality and Standard for Agro-Products, Zhejiang Academy of Agricultural Sciences, Hangzhou 310021, China.
authors.forename: Xueping
authors.initials: X
authors.lastname: Zhao
authors.affiliation: State Key Laboratory Breeding Base for Zhejiang Sustainable Pest and Disease Control/Key Laboratory for Pesticide Residue Detection of Ministry of Agriculture, Institute of Quality and Standard for Agro-Products, Zhejiang Academy of Agricultural Sciences, Hangzhou 310021, China. Electronic address: qiangwang2003@vip.sina.com.
authors.forename: Qiang
authors.initials: Q
authors.lastname: Wang
authors.affiliation: Key Laboratory of Agro-Product Quality and Safety of Ministry of Agriculture, Institute of Quality Standards and Testing Technology for Agro-Products, Chinese Academy of Agricultural Sciences, Beijing 100081, China. Electronic address: qyzcaas@aliyun.com.
authors.forename: Yongzhong
authors.initials: Y
authors.lastname: Qian
mesh_terms: D000083:Acetanilides / Q000633:toxicity; D000818:Animals; D004390:Chlorpyrifos / Q000633:toxicity; D004305:Dose-Response Relationship, Drug; D004347:Drug Interactions; D007093:Imidazoles / Q000633:toxicity; D015233:Models, Statistical; D000073943:Neonicotinoids; D009574:Nitro Compounds / Q000633:toxicity; D009835:Oligochaeta / Q000187:drug effects*; D010575:Pesticides / Q000633:toxicity*; D018570:Risk Assessment; D012989:Soil Pollutants / Q000633:toxicity*; D023382:Toxicity Tests, Acute
chemical_list: D000083:Acetanilides; D007093:Imidazoles; D000073943:Neonicotinoids; D009574:Nitro Compounds; D010575:Pesticides; D012989:Soil Pollutants; C082359:imidacloprid; C054409:butachlor; D004390:Chlorpyrifos
keywords: Acute mixture toxicity; Butachlor; Chlorpyrifos; Eisenia fetida; Imidacloprid