Microbial Degradation of Fipronil in Clay Loam Soil

Environmental fate and toxicology of fipronil

“…In both studies, the sterile soils had much longer dissipation times as compared to the non-sterile soils (Table 3). 21,23) Bacteria, fungi, and actinomycetes populations, as measured by plate counts, revealed no consistent pattern with fipronil concentration; the populations varied throughout the incubation period. 23)…”

“…However, shorter t 1/2 values about 10 days have been reported. 23) Similarly, about 14.5 days was found to be the t 1/2 for fipronil in pond water and sediment (aerobic), and the major degradation product was fipronil-sulfide. 18) Ying and Kookana 21) found that moisture in the soil determined the type of degradation product formed.…”

“…In contrast, soils with good aeration and less than 50% moisture had more fipronil-sulfone. Zhu et al 23) showed that temperature increased the dissipation time by about one day. In both studies, the sterile soils had much longer dissipation times as compared to the non-sterile soils (Table 3).…”

“…The microbial degradation of fipronil in soils was studied by Zhu et al 23) who found that the t 1/2 of fipronil in non-sterile clay loam was 9.72 and 8.78 days at 25°C and 35°C, respectively (Table 3); it took three times longer (approx. 33 days) in sterile soils.…”

Potential of some soil amendments in reducing leaching of fipronil to groundwater

“…Fipronil can undergo degradation in water and soil through abiotic and biotic processes resulting in the formation of fipronil sulfide through reduction, desulfinyl through photolysis (Fenet et al 2001), amide through hydrolysis (Bobe et al 1998b;Ramesh and Balasubramania 2009) and fipronil sulfone through oxidation (Zhu et al 2004). Fipronil sulfide, fipronil sulfone and desulfinyl are biologically active against insect pests, and their degradation is slow in soil as compared to parent fipronil.…”