Residue and dissipation dynamic of spinetoram insecticide in pear fruits

Abstract

Cacopsylla pyri (Linnaeus, 1758) is the most significant and widespread pear pest. It attacks the pear only, causing direct and indirect damages. This study was conducted in order to evaluate the efficacy of insecticide spinetoram in the control of C. pyri. The experiment was set up according to EPPO methods, at the locality Kula (Republic of Serbia) in a pear orchard (Williams variety). Spinetoram (250 g/kg a.i., WG) was foliar applied in the amount of 0.3 kg/ha, during overlapping pest generations, when pear was on BBCH 75 scale. The efficacy was evaluated through the number of larvae aged L<sub>1</sub>–L<sub>3</sub> and L<sub>4</sub>–L<sub>5</sub>. Spinetoram has shown satisfying efficacy, especially in the control of L<sub>1</sub>–L<sub>3</sub> larvae (81.6%). In a dissipation study, spinetoram residues in pear fruits were determined using QuEChERS method followed by HPLC-DAD. The method was validated to fulfill SANTE/12682/2019 criteria. Three days after the application, spinetoram residues in pear fruits were below the MRL (0.2 mg/kg). The results have shown that spinetoram dissipation pattern followed the first-order kinetics (R<sup>2 </sup>= 0.979) with a half-life of 2.17 days, in pear fruits. This study suggests that spinetoram could be safely used in pear, and it could take an important place in insecticide resistance management.

Development of a Modified QuEChERS Method Coupled with LC-MS/MS for Determination of Spinetoram Residue in Soybean (Glycine max) and Cotton (Gossypium hirsutum)

“…The recorded amount of terminal residues was lower than the prescribed MRL value (1 mg kg −1 ) of spinetoram in red bayberry [ 38 ]. Similar observations were found in various studies where spinetoram half-life values were reported as 1.29 d in cabbage, 1.95 d in pepper [ 39 ], 2.17 d in pear fruits [ 40 ], 2.6 d in tomato [ 41 ], 4.85 d in cauliflower [ 42 ] and 1.1 d in rice straw [ 16 ]. Faster dissipation of spinetoram from the plant surface may also be attributed to volatilization of the insecticide from the crop surface [ 41 ].…”