Dissipation kinetics and distribution of fipronil and its toxic metabolites in Banana, cv. Nendran (AAB)

Abstract

In the study under taken to analyze the dissipation, metabolism and persistence of fipronil in banana, cv. Nendran (AAB), in red loam soils (AEU 8-southern laterites) of Trivandrum, Kerala, India, with treatments as, absolute control (No application of fipronil), recommended practice of soil application of 30 mg a.i. of fipronil per plant per application, applied 3 times on 0, 60 and 150 days of planting and double dose of fipronil, in samples viz., leaves, fingers bunches and flower bud, central core of pseudo-stem and corm sampled and analyzed for residue at definite time intervals revealed that QuEChERS method can be conveniently applied for extracting the residue from various parts of banana plant and has resulted in satisfactory values for validation parameters. Residue of fipronil and their toxic metabolites in the 1st, 2nd and 3rd leaves of banana on penultimate day of completion of pre-bunching application was found to be below the detectable levels (BDL) throughout the period of sampling and this may be attributed to low absorption, very fast metabolism of very low levels of absorbed molecule and mobility. However, on 40th day the fipronil was detected in the 4th leaf to the extent of 0.034 μg g-1 and was not detectable (i.e., BDL) on 50th day indicating safety from residue of harvested produce for consumption especially at recommended dose. Sample matrices of blossom bud, flower bract alone, bunch on 15th day of emergence, bunch on 30th day of emergence, peel, bunch on harvest, pseudo stem and corm were below detectable level of fipronil and their metabolites and even with an additional application of treatment on the day of bunching also did not register any detectable level of fipronil and their metabolites.