Dissipation and residues of imidacloprid in amaranth under greenhouse and open field cultivations.

Despite the extensive exposure to imidacloprid residues in food plants, there has been little research on imidacloprid residues in amaranth. The dissipation trend and residue behavior of imidacloprid were evaluated to provide guidelines for imidacloprid application on amaranth under open field and greenhouse. The dissipation rate of imidacloprid in amaranth conformed to the first-order kinetic equation, and the half-lives of imidacloprid in amaranth ranged from 0.29 days in open field to 1.29 days in the greenhouse. After 7 and 14 days from the application of imidacloprid (pesticide dosage, 45 or 67.5 g a.i./ha), the amaranth under the open field and greenhouse growth could be consumed safely with average residues of 0.19 and 0.38 mg/kg, respectively. This result demonstrated that the cultivation has the dominant influence on imidacloprid residue, and the residue of imidacloprid in amaranth planting on open field was much lower than that in the greenhouse, indicating a significant difference in the pesticide residues between the two cultivations with a p-value less than 0.05.