Interaction of spirodiclofen, fenpyroximate, etoxazole, and imidacloprid for the control of two-spotted spider mite, Tetranychus urticae Koch

The interaction relationships of a binary mixture of spirodiclofen, fenpyroximate, and etoxazole acaricides, and mixing each of these acaricides with imidacloprid were investigated on deutonymph of Tetranychus urticae using the Potter spray tower method under controlled laboratory conditions. Based on the results of bioassay tests and combination index (CI) estimates, the toxicity of the binary mixture of the tested acaricides with each other and with imidacloprid on T. urticae was lower than that of each compound alone, and the interaction of their binary mixture was the antagonistic type. The measurement of the activity level of detoxifying enzymes in T. urticae treated with the LC50 concentration of pesticides and their binary mixture showed that the highest α- and β-esterase and glutathione S-transferase (GST) activities were observed in mites treated with spirodiclofen. Additionally, the highest cytochrome P450 monooxygenases (MFO) content was detected in mites treated with a mixture of spirodiclofen and imidacloprid. The results indicated that the application of a binary mixture of the mentioned acaricides together and in combination with imidacloprid leads to inefficient control of T. urticae.