Multi-location supervised field trials were conducted in India at four locations of the All India Network Project (AINP) on Pesticide Residues to study the persistence, dissipation and risk assessment of flubendiamide and deltamethrin on cucumber (Cucumis sativus). Residues of flubendiamide and deltamethrin on cucumber resulting from three spray applications of a combination formulation (flubendiamide 90% + deltamethrin 60%, 150 SC) at recommended (22.5 + 15 g a.i./ha) and double the recommended (45 + 30 g a.i./ha) dose were analysed. On the basis of persistence and dissipation studies, the half- life (T) of flubendiamide on cucumber varied from 1.40 to 2.98 (recommended dose) and 1.55 to 2.76 days (double the recommended dose), while that of deltamethrin ranged from 2.5 to 4.9 (recommended dose) and 2.7 to 3.9 days (double the recommended dose) at the four locations. On the basis of supervised field trial data and using OECD calculator, MRLs in the combination product of 3 mg kg for flubendiamide and 1.5 mg kg for deltamethrin has been proposed for consideration by the Food Safety and Standards Authority of India (FSSAI). Codex, EU and EPA have fixed MRL of 0.2 mg kg for flubendiamide and deltamethrin.
This investigation was undertaken to compare the dissipation pattern of flubendiamide in capsicum fruits under poly-house and open field after giving spray applications at the recommended and double doses of 48 g a.i. ha(-1) and 96 g a.i. ha(-1). Extraction and purification of capsicum fruit samples were carried out by the QuEChERS method. Residues of flubendiamide and its metabolite, des-iodo flubendiamide, were analyzed by high-performance liquid chromatography-photodiode array, and confirmed by liquid chromatography-mass spectrometry/mass spectrometry. Limit of quantification of the method was 0.05 mg kg(-1), and recovery of the insecticides was in the range of 89.6-104.3%, with relative standard deviation being 4.5-11.5%. The measurement uncertainty of the analytical method was in the range of 10.7-15.7%. Initial residue deposits of flubendiamide on capsicum fruits grown under poly-house conditions were (0.977 and 1.834 mg kg(-1)) higher than that grown in the field (0.665 and 1.545 mg kg(-1)). Flubendiamide residues persisted for 15 days in field-grown and for 25 days in poly-house-grown capsicum fruits. The residues were degraded with the half-lives of 4.3-4.7 and 5.6-6.6 days in field and poly-house respectively. Des-iodo flubendiamide was not detected in capsicum fruits or soil. The residues of flubendiamide degraded to below the maximum residue limit notified by Codex Alimentarius Commission (FAO/WHO) after 1 and 6 days in open field, and 3 and 10 days in poly-house. The results of the study indicated that flubendiamide applied to capsicum under controlled environmental conditions required longer pre-harvest interval to allow its residues to dissipate to the safe level.
IntroductionBrinjal (also known as eggplant and aubergine) and okra (lady's finger) are the two most common and popular vegetable crops grown extensively throughout India. India is the largest producer of okra in the world [1]. The major insect pests of brinjal are shoot and fruit borer (Leucinodes orbonalis Guenee), hadda beetle (Epilachna spp.), Jassid, (Amrascabiguttulabiguttula Ishida), aphid (Aphis gossypii Glover), stem borer (Euzopheraperticella Ragonot), white fly (Bemisiatabaci Gennadius), and the lace wing bug (Urentiusechinus Distant) [2]. The brinjal shoot and fruit borer causes shading of flower buds and reduces the brinjal yield, causing up to 70% damage to the crop at fruiting stage and making it unfit for human consumption Pol. J. Environ. Stud. Vol. 26, No. 3 (2017) This study reports on the dissipation of acephate residues on brinjal and okra and the formation of the metabolite methamidophos. The QuEChERS method in conjunction with gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS) was used for analyzing acephate and methamidophos in brinjal and okra. The limit of detection (LOD) and limit of quantification (LOQ) were 0.003 and 0.01 mg kg -1 for both compounds, respectively. The recoveries were between 76.6-99.5% with the relative standard deviation (RSD) between 3.2-11.8% (n = 6). The measurement uncertainty (MU) was between 9.9-17.5% at 95% confidence level. The initial residues of acephate were 8.61 and 13.63 mg kg -1 on brinjal, and 8.44and 15.05 mg kg -1 on okra from treatments at the standard and double doses of 560 and 1,120 g a.i. ha -1 , respectively. The concentration of methamidophos increased up to the third day on brinjal and okra and decreased thereafter. Methamidophos was more persistent than acephate. The pre-harvest intervals (PHI) required for dissipation of the combined residues of acephate and methamidophos to below the European Union maximum residue limits were 47 days for brinjal and 25 days for okra. The results of the study can be utilized for use of acephate in plant protection of brinjal and okra.
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