Cypermethrin is a synthetic insecticide of the pyrethroid family, which derive from botanical pyrethrins. Cypermethrin is classified as a Type II pyrethroid due to its alpha-cyano group. In the United States, about 1 million pounds of cypermethrin are applied annually, mostly to cotton crops (US EPA, 2008). Cypermethrin has relatively low toxicity for mammals and birds, although it is highly toxic for fish and aquatic invertebrates (Bradbury and Coats, 1989).
The major route of cypermethrin biodegradation begins with ester hydrolysis (Roberts TR and Standen ME, Pest Management Science, 8:305-319, 1977), a common initial step in pyrethroid metabolism, to produce the carboxylate, 3-(2,2-dichloroethenyl)-2,2-dimethylcyclopropanecarboxylate. The other product, cyano-3-phenoxybenzyl alcohol, contains the cyanohydrin functional group, which is unstable in the presence of water. The cyanohydrin eliminates HCN in a non-enzymatic reaction to produce 3-phenoxybenzaldehyde (Shono et al., 1979).
The following is a text-format cypermethrin pathway map. Organisms that can initiate the pathway are given, but other organisms may also carry out later steps. Follow the links for more information on compounds or reactions. This map is also available in graphic (16k) format.
Cypermethrin
Achromobacter sp. SM-2
Pseudomonas fluorescens SM-1
Bacillus cereus SM-3
Klebsiella sp. ZD112
Sphingobium sp. JZ-1
Sphingobium sp. JZ-2
Aspergillus niger ZD11
Ochrobactrum lupini DG-S-01
Streptomyces aureus HP-S-01
Streptomyces sp. HU-S-01
Pseudomonas stutzeri
Micrococcus sp. CPN 1
Serratia sp. JC1
Serratia sp. JCN13
|
|
| pyrethroid hydrolase
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|
v
(RS)-alpha-Cyano-3- + 3-(2,2-dichloroethenyl)-
phenoxybenzyl alcohol 2,2-dimethylcyclopropanecarboxylate
| |
| |
| A v B
| |
| |
v v
3-Phenoxybenzaldehyde CO2
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|
|
|
|
v
to the
Permethrin
Pathway
Page Author(s): Jeffrey P. Osborne, Manchester College
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