title: Individual and combined toxic effects of cypermethrin and chlorpyrifos on earthworm.
abstract: Toxicities were assessed for a pyrethroid (cypermethrin) and an organophosphate insecticide (chlorpyrifos) individually and in combination. A series of tests were conducted on different responses (acute, chronic, behavioral) of earthworms of species Eisenia fetida andrei in the ecological risk assessment of these pesticides. The results showed that the toxicity of the mixture of cypermethrin and chlorpyrifos was significantly higher than either of these pesticides individually, especially on the earthworm's chronic responses. At a concentration of 5 mg/kg, the mixture caused significant reductions on the growth and reproduction rates of earthworms, but did not cause any significant effect when the individual was tested. The increase in toxicity of the pesticide mixture means that the use of toxicity data obtained exclusively from single-pesticide experiments may underestimate the ecological risk of pesticides that actually present in the field.
authors.affiliation: Key Laboratory for Forest Resources Conservation and Use in the Southwest Mountains of China of Ministry of Education, Southwest Forestry University, Kunming 650224, China. kmzhoushiping@163.com
authors.forename: Shiping
authors.initials: S
authors.lastname: Zhou
authors.forename: Changqun
authors.initials: C
authors.lastname: Duan
authors.forename: Wong Hang Gi
authors.initials: WH
authors.lastname: Michelle
authors.forename: Fazhong
authors.initials: F
authors.lastname: Yang
authors.forename: Xuehua
authors.initials: X
authors.lastname: Wang
mesh_terms: D000818:Animals; D001362:Avoidance Learning / Q000187:drug effects; D004390:Chlorpyrifos / Q000633:toxicity*; D023381:Endpoint Determination; D009835:Oligochaeta / Q000187:drug effects* / Q000254:growth & development; D010575:Pesticides / Q000633:toxicity; D011722:Pyrethrins / Q000633:toxicity*; D012098:Reproduction / Q000187:drug effects; D023382:Toxicity Tests, Acute
chemical_list: D010575:Pesticides; D011722:Pyrethrins; C017160:cypermethrin; D004390:Chlorpyrifos