Study of dissipation dynamics and persistent toxicity of selected insecticides in chilli using LCMSMS

Chilli, a globally cultivated and consumed crop is significantly impacted by Thrips parvispinus. The reliance on pesticides could result in residue contamination, adversely affecting quality, leading to export rejections and health risks to consumers. This study evaluated the bioefficacy and persistent toxicity of fipronil and tolfenpyrad against thrips in chilli, and persistence of their residues. Tolfenpyrad demonstrated higher field efficacy (60.94 to 78.53%) against thrips compared to fipronil (37.61 to 58.07%). Residue analysis was performed in leaves and green chilli fruits using LC-MS/MS. Fipronil's efficacy decreased after 5 to 7 days of application, but both fipronil and tolfenpyrad residues remained for 20 and 30 days, respectively. In contrast, the residues in leaves caused persistent toxicity to thrips, causing about 50% mortality until 10 to 15 days in tolfenpyrad treatment. In green chilli, residues of tolfenpyrad and fipronil persisted for up to 40 and 25 days, necessitating pre-harvest intervals of 3.17 and 19.39 to 30.65 days, respectively, but with no dietary risk to consumers. Tolfenpyrad exhibited superior efficacy against T. parvispinus compared to fipronil, with a longer duration of effectiveness in leaves and quicker residue dissipation in chilli fruits and a short pre-harvest interval, supporting its use in Integrated Pest Management.