Degradation kinetics of three pyrethroid insecticides by strain DG-S-01 in flowering Chinese cabbage and soil

Degradation kinetics of beta-cypermethrin,lambda-cyhalothrin and fenvalerate by Ochrobactrum sp.strain DG-S-01 in flowering Chinese cabbage (Brassica campestris L.sp.) and soil were investigated by pot and field plot experiments.The results showed that strain DG-S-01 could effectively degrade these pyrethroid residues in flowering Chinese cabbage and soil.The degradation followed first-order kinetics and the half lives (t1/2) shortened by 1.5-53.2 h compared with control.The results also indicated that the pyrethroid residues in flowering Chinese cabbage evidently decreased as increase of treatment time.The residues of beta-cypermethrin and lambda-cyhalothrin in flowering Chinese cabbage were below 0.5 mg/kg after 72 h from treatment.The residues of beta-cypermethrin and lambda-cyhalothrin in soil also decreased as increase of treatment time,and the residues were below 1 mg/kg after 72 h.But it’s observed that the fenvalerate residues in soil increased first,then decreased with the extension of treatment time.The pyrethroid residues in flowering Chinese cabbage and soil after treated with strain DG-S-01 were significantly lower than the control.