Effects of neonicotinoid residues in Apis cerana indica bees and bee products: LC-MS/MS analysis and dietary risk assessment in a sunflower field study.

Abstract

Bee colony decline, including in Apis cerana indica F., is a global concern linked to multiple factors, notably neonicotinoid insecticides. Residues in honey and pollen threaten bees and humans when exceeding safe levels, necessitating critical assessments of daily exposure thresholds. A controlled field experiment and dietary risk assessment studies were conducted to identify the impact of neonicotinoids. The LC-MS/MS method was developed to analyze residue in bee products. A survey of eight locations showed that only two honey samples, each from a different location, were contaminated with imidacloprid (0.03 µg g^-1) and acetamiprid (0.07 µg g^-1) residues. Similarly, a separate field experiment in sunflower detected neonicotinoid residues (0.025-0.456 μg g^-1) in bee products. The field experiment indicated significantly higher bee mortality in the clothianidin sprayed field, using dead bee trap (88.00 bees) and cotton fabric spread (10.50 bees), than in the control field one day after spraying (DAS). Foraging activity significantly improved in the control plots, with increased incoming nectar (7.18 bees/min) and outgoing forager activity (13.28 bees/min) at 15 DAS. Colony growth parameters, namely, honey (61.88 cm²), pollen (41.25 cm²), brood area (91.00 cm²), and population (3479.50 bees) were highest in the control. The yield parameters followed the descending order of control > dimethoate > thiacloprid > imidacloprid > thiamethoxam > clothianidin. The dietary neonicotinoid residue risk evaluation showed moderate-high risk (risk quotient > 5) for bees but tolerable hazard (hazard quotient < 1) for humans. Hence, these neonicotinoid effects should be further explored through comprehensive risk analysis to safeguard native bee populations while maintaining effective crop protection practices.