title: Comparison of the acute toxicity for gamma-cyhalothrin and lambda-cyhalothrin to zebra fish and shrimp.
abstract: Gamma-cyhalothrin 15CS (GCH) contains only the active stereoisomer of the two isomers found in lambda-cyhalothrin 25EW (LCH). GCH (0.5 x rate) provides equivalent overall insect control as LCH (1 x rate). Both formulations showed high acute toxicity to zebra fish (Brachydanio rerio H.B.) and shrimp (Macrobrachium nippoensis de Haan). The 96-h LC(50(zebra fish,GCH)) is 1.93 microg a.i/L and LC(50(zebra fish,LCH)) is 1.94 microg a.i/L. LC(50(shrimp,GCH)) is 0.28 microg a.i./L and LC(50(shrimp,LCH)) 0.04 microg a.i./L. This indicates that the toxicity to shrimp is likely stereochemistry-dependent. The fates of GCH and LCH are similar in laboratory simulated rice paddy water and their concentrations decrease rapidly, with no GCH or LCH detected after 3 or 4 days. Both are toxic to shrimp in a simulated paddy irrigation reservoir even though treated return water is diluted 5 times. No shrimp fatality is shown in the GCH-treated paddy water after a 4-day holding period, and longer than 5 days is necessary to reach a zero fatality rate for LCH. This is compatible with the 7-day water holding period considered reasonable in agricultural practice.
authors.affiliation: College of Agronomy and Biotechnology, China Agricultural University, Beijing 100094, China.
authors.forename: Wei
authors.initials: W
authors.lastname: Wang
authors.forename: D J
authors.initials: DJ
authors.lastname: Cai
authors.forename: Z J
authors.initials: ZJ
authors.lastname: Shan
authors.forename: W L
authors.initials: WL
authors.lastname: Chen
authors.forename: Nick
authors.initials: N
authors.lastname: Poletika
authors.forename: X W
authors.initials: XW
authors.lastname: Gao
mesh_terms: D000818:Animals; D004305:Dose-Response Relationship, Drug; D007306:Insecticides / Q000633:toxicity*; D007928:Lethal Dose 50; D009570:Nitriles / Q000737:chemistry / Q000633:toxicity*; D033541:Palaemonidae / Q000378:metabolism*; D011722:Pyrethrins / Q000737:chemistry / Q000633:toxicity*; D013237:Stereoisomerism; D023382:Toxicity Tests, Acute; D015027:Zebrafish / Q000378:metabolism*
chemical_list: D007306:Insecticides; D009570:Nitriles; D011722:Pyrethrins; C037304:cyhalothrin