Comparison of the acute toxicity for gamma-cyhalothrin and lambda-cyhalothrin to zebra fish and shrimp.
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.
Wang
Wei
W
College of Agronomy and Biotechnology, China Agricultural University, Beijing 100094, China.
Cai
D J
DJ
Shan
Z J
ZJ
Chen
W L
WL
Poletika
Nick
N
Gao
X W
XW
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*
D007306:Insecticides; D009570:Nitriles; D011722:Pyrethrins; C037304:cyhalothrin