Evolving resistance patterns in Tetranychus urticae and Bemisia tabaci in Greece

Abstract

Pesticide resistance in agricultural pests poses a significant challenge to sustainable crop protection. In this study, we assessed the current resistance status of two key pests, Tetranychus urticae and Bemisia tabaci, in major agricultural regions of Greece. A total of 25 field populations were collected between 2023 and 2025 and tested using single-dose toxicity bioassays and droplet digital PCR (ddPCR) for known resistance-associated target-site mutations. The results revealed significant variability in susceptibility to multiple acaricides and insecticides, with several T. urticae populations displaying reduced sensitivity to abamectin, hexythiazox, and fenpyroximate. Resistance mutations such as I321T (GluCl3), I1017F (CHS1), F1538I (VGSC), and G126S (cytb) were detected at high frequencies in multiple populations, indicating multi-resistant phenotypes. In B. tabaci, widespread occurrence of F331W (ace1), L925I/T929V (VGSC), and A2083V (acc) mutations confirmed evolving resistance to organophosphates, pyrethroids, and ketoenols, respectively. Our findings underscore the ongoing evolution of resistance in these pests and highlight the need for integrated management strategies that include regular resistance monitoring and judicious pesticide use. This study provides data to guide evidence-based pest control and supports the implementation of sustainable Integrated Pest Management (IPM) practices in Greece.