Potential Impact of Some Soil Borne Fungi on Biodegradation of Some Organophosphorous Nematicides

Abstract

Organophosphorous nematicides are highly toxic pesticides used to control nematodes in agriculture soil. An in vitro Biodegradation study was conducted to determine the biodegradability of, ethoprophos, fenamiphos and triazophos nematicides, using fungi strains isolated from sandy agriculture soil under date palm trees. Five fungi strains labeled as S1 (Fusarium oxysporum), S2(Aspergillus flavus), S3 (Aspergillus fumigatus), S4 (Fusarium moniliforme) and S5 (Trichothecium roseum) were isolated and identified, then incubated with nematicides at successive intervals untill 45 days in liquid medium paralleled with control samples. Recovery rates were performed at two levels 0.1 and 1 mg kg-1, values were over 90% for all nematicides. Limit of detection values (LOD) were 0.010, 0.012 and 0.011 mg kg-1 and limit of quantitation values (LOQ) were 0.033, 0.040 and 0.036 mg kg-1 respectively. Data indicated that S1 (Fusarium oxysporum) and S2 (Aspergillus flavus) accelerated the degradation rate of all mentioned nematicise, and S2 had the highest impact more than S1, while the other strains had no significant effect. Half-life values (RL50) for nematicides with S1 were 18.15, 16.65 and 15.24 days, respectively, and with S2 were 10.35, 13.87 and 11.18 days, respectively, while control values were 26.30, 24.28 and 26.70 days, respectively.