Degradation Dynamics of Flonicamid Insecticide Residues in Rice Crop and Soil in Southern Kerala and Its Dietary Risk Assessment

Abstract

Flonicamid is extensively used to manage rice crop from sucking insect pests owing to its high efficacy and relatively non-hazardous nature. Frequent sprayings over the course of the crop season elevate concerns regarding the possibility of residues on crops and soils. The study aimed to investigate the dissipation of foliar-applied flonicamid in rice ecosystem after single, double and triple application frequencies using a modified QuEChERS method combined with UHPLC-MS/MS. Recoveries of 74.34-116.36% were obtained for flonicamid in rice and soil matrices with relative standard deviation less than 7 and Horwitz ratio within 0.3. In the field experiment, flonicamid had half-lives of 2.75 to 3.15 days in leaves and 9.01 days in grains. No significant differences in residues were found after each application frequency owing to the similar environmental conditions prevailed during the growing season. A waiting period of 25 days is recommended for flonicamid when considering crop use for fodder purposes. In soil, no residues were detected regardless of the frequency of application. Upon harvest, residues were detected only in grains treated three times with flonicamid. Dietary risk assessment indicated that risk quotient values were below 1, suggesting no associated risks.