diafenthiuron and chlorfenapyr

Recently, chlorfenapyr and diafenthiuron have been widely used to prevent and control diseases and pests in tea production. However, rare studies have investigated the dissipation patterns of chlorfenapyr, diafenthiuron and their metabolites simultaneously in tea matrices. Here, we established an analytical method to investigate the degradation patterns of five target compounds in tea shoots and made tea samples. Moreover, the dietary intake risk assessment of chlorfenapyr-diafenthiuron mixture among Chinese populations was evaluated based on the supervised field experiment.. The mean recoveries of the primary analytes at five spiking levels were between 95.6% and 112.6% in tea shoots and made tea, respectively, and the values of RSD (relative standard deviation) were lower than 9.7% for all the target analytes. The field trial results showed that the half-lives of chlorfenapyr and diafenthiuron based on the residue definition were 10.0-12.4 days and 4.3-5.9 days, respectively, in tea shoots. For the dietary intake risk assessment, the risk quotient (RQ) values in made tea ranged from 30.4% to 73.9% at the pre-harvest interval of 14 days, which were significantly less than 100%.. The accuracy and precision of the developed method were satisfied by the measurement requirements according to the validation results. The dynamic dissipation experiments suggested that diafenthiuron was much easier to dissipate than chlorfenapyr. Moreover, the existence of tralopyril made the half-life of chlorfenapyr significantly increase, indicating that practical application of chlorfenapyr should take careful consideration of its metabolite. Finally, the potential chronic dietary risks of the chlorfenapyr-diafenthiuron mixture to human communities were within the acceptable range. © 2022 Society of Chemical Industry.

Topics: Eating; Humans; Pesticide Residues; Phenylthiourea; Pyrethrins; Risk Assessment; Tea; Trees

The diamondback moth (DBM), Plutella xylostella (L.) (Lepidoptera: Plutellidae), is a globally distributed and important economic pest. Chemical control is the primary approach to regulate populations of this pest. However, resistance to insecticides evolves following heavy and frequent use. Therefore, the insecticide resistance in field populations of P. xylostella collected from Central China from 2013 to 2014 was determined with a leaf-dipping method. Based on the results of the monitoring, P. xylostella has developed high levels of resistance to beta-cypermethrin (resistance ratio=69.76-335.76-fold), Bt (WG-001) (RR=35.43-167.36), and chlorfluazuron (RR=13.60-104.95) and medium levels of resistance to chlorantraniliprole (RR=1.19-14.26), chlorfenapyr (RR=4.22-13.44), spinosad (RR=5.89-21.45), indoxacarb (RR=4.01-34.45), and abamectin (RR=23.88-95.15). By contrast, the field populations of P. xylostella remained susceptible to or developed low levels of resistance to diafenthiuron (RR=1.61-8.05), spinetoram (RR=0.88-2.35), and cyantraniliprole (RR=0.4-2.15). Moreover, the LC50 values of field populations of P. xylostella were highly positively correlated between chlorantraniliprole and cyantraniliprole (r=0.88, P=0.045), chlorantraniliprole and spinosad (r=0.66, P=0.039), spinosad and diafenthiuron (r=0.57, P=0.0060), and chlorfenapyr and diafenthiuron (r=0.51, P=0.016). Additionally, the activities of detoxification enzymes in field populations of P. xylostella were significantly positively correlated with the log LC50 values of chlorantraniliprole and spinosad. The results of this study provide an important base for developing effective and successful strategies to manage insecticide resistance in P. xylostella.

Topics: Animals; Bacillus thuringiensis; China; Drug Combinations; Insecticide Resistance; Insecticides; Ivermectin; Macrolides; Moths; ortho-Aminobenzoates; Oxazines; Phenylthiourea; Phenylurea Compounds; Pyrazoles; Pyrethrins; Pyridines