Residue status and risk assessment of neonicotinoids under real field conditions: Based on a two-year survey of cotton fields throughout China

Abstract

There is considerable controversy regarding the harm caused by neonicotinoids to pollinators. Oilseed rape, corn and wild flowers, but not cotton, have been identified as important for toxicity risk of neonicotinoids to pollinators. To this end, 396 stamens and maternal flowers from major cotton areas across China were analyzed, 97.3% (2020) and 100% (2021) of samples contained at least one neonicotinoid pesticide. The probability of multiple residues was greater than that of a single neonicotinoid residue, and there was no significant difference between stamen and maternal flowers. The median total concentration of neonicotinoids ranged from 3.73 to 638 ng g −1 . Acetamiprid (detection rate ratio (DRR): 14.3%; concentration ratio (CR): 53.1%), dinotefuran (DRR: 23.3%; CR: 19.9%), and clothianidin (DRR: 21.1%; CR: 6.49%) were the most frequently detected neonicotinoids. Based on the Hazard Quotient (HQ) assessment, acetamiprid, clothianidin and dinotefuran (median HQ value > 1,000) reached the risk level; while the Risk Quotient (RQ) assessment indicated that they have not yet reached the degree of risk concern (median RQ value < 0.4). This research provides the first overview of neonicotinoid residues in cotton field, and supplements the data of cotton field planting for international risk assessment of neonicotinoids. • Neonicotinoid insecticides were detected in 98.6% of cotton flowers. • Multiple neonicotinoid residues have a higher detection rate than single residues. • The number of neonicotinoids detected mostly ranged from 3–5. • The risk of neonicotinoids to honeybees was assessed using HQ and RQ models. • Acetamiprid, clothianidin, and dinotefuran are the most common and potentially risky neonicotinoids.