Abamectin resistance and resistance mechanisms in Tetranychus urticae populations from cut flowers greenhouses in Turkey

Tetranychus urticae Koch is a common pest of many crops in Turkey and the world. In this study, abamectin LC values, resistance rates, detoxification enzyme activities and the presence of G314D point mutation in the target site were investigated in T. urticae collected from cut flower production greenhouses in Antalya. The LC values of the susceptible and field populations were determined by spray tower-leaf disc method. The resistance rates of field populations ranged from 1.60 to 850.12-fold compared to the susceptible population. Activities of three detoxification enzymes were determined by a microplate reader. The activity of esterase and GST ranged from 4.04 to 8.21 and from 4.40 to 11.69 mOD min-1 mg-1 proteins, respectively, in different populations. On the other hand, the P450 enzyme activity of the field populations was 0.52-1.80 RFU 30 min-1 mg-1 protein. Screening the populations for the presence of G314D point mutation in glutamate-gated chloride channels (GluCls) by real-time PCR using the mutation-specific TaqMan probe revealed no mutations in any populations tested. The results showed that the resistance in the populations tested in this study is likely associated with activity of detoxifying enzymes rather than target site mutations in the GluCls channels.