Spinosad residues in hydroponically grown tomato fruits
Hydroponic cultivation improves the yield and product quality of greenhouse-grown vegetables while it decreases water requirements and decreases the application of plant protection products (PPPs). Within this context, an experiment was conducted at the greenhouse of the Laboratory of Vegetable Production at the Agricultural University of Athens. Tomato plants (Solanum lycopersicum L. 'ELPIDA F1') were grown in an open hydroponic system using perlite as substrate. The greenhouse was equipped with nets and sticky traps to control pests, and the predatory mirid Macrolophus pygmaeus (Hemiptera: Miridae) was used as a biological PPPs. Nevertheless, due to infestation by Tuta absoluta, a spinosad-based PPPs was applied 42 days before the first harvest while the recommended pre-harvest interval (PHI) is 3 days. The commercially ripe fruits were harvested at 9 weeks and 11 weeks after transplanting. To ensure that the tomato fruits were free of insecticide residues, the extra class fruits were analyzed by employing a multi-residue analytical method. The method was capable of determining both spinosyn A and spinosyn D, the two isomers which comprise the definition of residue for this insecticide, with a limit of quantification (LOQ) of 0.01 mg kg‑1. Analyses revealed no detectable residues of spinosad in the harvested tomato fruits. Results suggest that although the application of PPPs is inevitable in hydroponic cultivation, the prolongation of the approved PHI can contribute to the minimization of spinosad residues in tomato fruits, and plausible other PPPs, thus, enhancing food safety.
Lykogianni, M., Bempelou, E., Ntatsi, G., Karavidas, I., Ropokis, A., Aliferis, K.A. and Savvas, D. (2021). Spinosad residues in hydroponically grown tomato fruits. Acta Hortic. 1320, 197-204
Solanum lycopersicum, soilless culture, Tuta absoluta, plant protection, insecticide