Assessment of deltamethrin efficacy and residue dissipation dynamic in paprika fruits

Abstract

Pyrethroid insecticides are still widely used to control H. armigera in paprika. Therefore, evaluating their efficacy, the presence of residues, and the dissipation dynamics is necessary. A field experiment was conducted according to standard EPPO methods, at the locality Gospođinci, Serbia. Insecticide based on deltamethrin (25 g a.i./l, EC), was applied foliar at the recommended dose of 0.7 l/ha in paprika (Elephant Ears variety) when the paprika was in the stage BBCH 81. The efficacy was evaluated through the number of damaged fruits 8 and 14 days after the application. Eight days after application, the efficacy was 93.1%, while after 14 days, it was 84.4%, with damage significantly lower than in the control. To analyze deltamethrin residue in paprika fruits, samples were collected one hour after the application and daily for one week. A method for the determination of deltamethrin residues has been validated, with satisfactory validation parameters in terms of linearity, precision, recovery and limits of detection and quantification. The highest amount of deltamethrin (0.37 mg/kg) in paprika samples was found 1h after the application, while between first and second day after the treatment residues were at the MRL level of 0.15 mg/kg. Results obtained for the dissipation dynamics experiment showed that deltamethrin degraded immediately, with a half-life of 1.92 days in paprika fruits. Thus, pyrethroid insecticides can be safely used for the control of H. armigera in paprika.