Buprofezin dissipation and safety assessment in open field cabbage and cauliflower using GC/ITMS employing an analyte protectant.

An analytical method for the determination of buprofezin residues in cabbage and cauliflower was developed and validated using gas chromatography with ion trap mass spectrometry. The analyte protectant d-sorbitol was used at a concentration level of 0.5 mg mL-1 in acetonitrile instead of in matrix for constructing the calibration curves of the buprofezin standard. The average recoveries ranged from 91.3 to 96.8%, with an RSD of ≤2.7%. The limits of detection and quantitation of the method in cabbage and cauliflower were 1.3, 1.7 and 4.3, 6.2 µg kg-1 , respectively. The residual levels and dissipation kinetics of buprofezin 25% wettabe powder in cabbage and cauliflower cultivated under open field conditions was investigated at the single (T1) and double (T2) recommended rates of application. Half-life periods were found to be 1.73 and 2.1 days in cabbage, whereas in cauliflower, these values were 1.85 and 2.36 days at T1 and T2, respectively. Based on the dissipation study, and the maximum residue limit value of 0.05 mg kg-1 , the proposed pre-harvest interval of buprofezin in cabbage was 3-6 days and that in cauliflower was 4-10 days. The results showed that buprofezin is safe for application at both recommended application rates.

Effects of biochar amendment on sorption, dissipation, and uptake of fenamiphos and cadusafos nematicides in sandy soil.

BACKGROUND: The application of biochar to soil is supposed to alter its adsorption/desorption potential toward pesticides, thereby affecting their bioavailability and efficacy. This is particularly relevant in the case of nematicides because these pesticides are directly applied to soil. RESULTS: Biochar was produced from date palm (PB) and eucalyptus (EB) waste at 450 °C and added at a rate of 1% to a sandy soil. The half-life (t½ ) of fenamiphos was increased from 2.7 to 18.3 and 18.6 days in PB- and EB-amended soils, respectively. By contrast, the half-life of cadusafos was unaffected. Freundlich Kf values increased from 1.22 and 0.39 (µg1-Nf g-1 mLNf ) to 4.49 and 6.84 in 1% PB-amended soil, and to 3.49 and 4.62 in 1% EB-amended soil for cadusafos and fenamiphos, respectively. Plant uptake of both nematicides in tomato seedlings was reduced by approximately 97% (cadusafos) and 85% (fenamiphos). Although nematicide efficacy against Meloidogyne incognita was not altered at the recommended dosage, it was negatively affected at a half-dose rate. Under these conditions, it decreased from 43.1% in unamended sandy soil to only 18.3% in 1% PB-amended soil. CONCLUSIONS: Biochar addition increased the sorption capacity of soil. This resulted in a decrease of nematicide bioavailability, together with a reduction of both the dissipation rate and uptake by tomato plants. © 2018 Society of Chemical Industry.

Antifungal action of Pichia anomala against aflatoxigenic Aspergillus flavus and its application as a feed supplement.

BACKGROUND: The disastrous problem of animal feed contamination by mycotoxigenic fungi continues to challenge researchers and health overseers worldwide. With the aim of preventing Aspergillus flavus growth in vitro and in corn feed, the yeast Pichia anomala was examined as a biocontrol agent. RESULTS: The yeast strain could efficiently prohibit the growth of A. flavus. P. anomala was able to produce exo-chitinase and ß-1,3-glucanase which could be suggested as a mode of action for its antifungal activity. Scanning electron microscopy of cultured P. anomala with fungal hypha revealed that A. flavus was colonised by the biocontrol yeast which subsequently led to complete hyphal lysis and deterioration. The supplementation with of P. anomala cells, as a protein source, led to an obvious increase in animals' weight gain and protein content in feed grain. Moreover, after consumption of P. anomala-supplemented feed, there was a remarkable decrease in the mortality rate among fed animals. CONCLUSION: P. anomala could be strongly recommended as a biocontrol agent against A. flavus which contaminates animal feed. Furthermore, the application of yeast cells, as a feed additive, proved its efficiency for escalating protein content and enhancing animal performance.