The effect of soil temperature on the degradation of CLS, trans – permethrin in soil

Abstract

The degradation of [carbonyl ‐ ¹⁴C] ‐ cis, trans‐permethrin was studied in Dubbs fine sandy loam soil incubated at 10, 25, and 40°C from 0 to 64 days. The most rapid degradation of permethrin to [carbonyl ‐ ¹⁴C] ‐ cis,‐trans ‐3‐ (2,2‐dichloroethenyl)‐2,2‐dimethylcyclopropanecarboxylic acid (DCVA) and ultimately ¹⁴CO₂ occurred at 25°C. Rapid degradation to DCVA also occurred at 40°C, however, further degradation of DCVA to ¹⁴CO₂ was reduced. Permethrin degradation to ¹⁴CO₂ was slowest at 10°C. The de gradation rate of trans‐permethrin was greater than the cis‐permethrin at all temperatures tested. The halflives of cis‐and trans‐permethrin were 55 and 14 days at 10°C, 12 and 5 days at 25°C, and 27 and 4 days at 40°C, respectively. Compounds identified from treated soil were the original [carbonyl ‐ ¹⁴C] ‐cis, trans‐permethrin and the major degradation products cis‐, and trans‐DCVA.

Key words:

• permethrin
• insecticide
• metabolism
• microbial degradation
• soil temperature