Pyridaben resistance in Tetranychus urticae in Israel

Abstract: Our research focuses on different aspects of acaricide resistance of the pest mite
Tetranychus urticae. During 2023, we have been collecting samples of T. urticae from outbreaks all over Israel and conducting tests to assess their resistance levels to thirteen acaricides from eight IRAC MoA (Mode of Action) classes. One class of acaricides we focus on is the 21A, targeting electron transport on the mitochondrial complex I (MET-I acaricides). Our survey indicates that pyridaben has completely lost its effectiveness in Israel. When examining previously published pyridaben resistance markers, we were unable to link them to resistance phenotypes seen in the field. However, we were able to locate a new SNP mutation that is associated with resistance in our Israeli samples. We tested selected populations for possible metabolic resistance and assessed life history traits such as longevity and fecundity. We note that certain populations show extreme cases of cross-resistance, to all licenced 21A compounds in commercial use in Israel, indicating the evolution of a common resistance mechanism. But not all is bad; when assessing life history traits of selected resistant populations, we came across several evidences of fitness costs.