Insecticides in Bait Spray Solutions: Validation, Determination, and Stability: The Role of Trophic Attractants

In Greece, the protection of olive orchards against the olive fruit fly (Bactrocera oleae), the most serious pest of olive fruits, is implemented through a national control program. This program is implemented by the Ministry of Rural Development and Food in co-operation with various public and private organizations. A new approach followed for this goal is the use of insecticide spray solutions combined with trophic attractant to attract and kill the olive fruit fly. In the present study, a method for the determination of the major insecticides, lambda-cyhalothrin and Spinosad, in their spraying solutions in combinations with trophic attractants was developed and validated and the monitoring of their residual concentration under various temperature conditions was examined. The reliability of the analytical method was achieved by obtaining acceptable results regarding the core criteria of specificity, linearity (R2 ≥ 0.99), accuracy (recoveries ranged from 91.01% to 116.29%), and precision (RSDs ranged from 0.47% to 3%). Furthermore, no significant effect on the stability of lambda-cyhalothrin and spinosad was noted from the various attractants that were added. As it was observed, in all cases the concentration of the insecticide remained stable. On the other hand, the effect of temperature as well as pH seems to be significant, with the degradation rates at 30 °C clearly higher in all cases than those at 20 °C. Therefore, preliminary data have been provided on recording the duration that the formulation remains stable and effective in spray solutions.