Selection for resistance: Cross-resistance, inheritance, synergists and biochemical mechanisms of resistance to acequinocyl in Phytoseiulus persimilis A.H. (Acari: Phytoseiidae)

The predatory mite Phytoseiulus persimilis is effective in controlling tetranychids on many cultivated crops. The LC50 and LC60 values of acequinocyl were determined for P. persimilis using a leaf-disc method and a spraying tower. A laboratory population ACE6 had a 32.75-fold increase in resistance to acequinocyl after six selection cycles. This resistant population also developed low resistance to spinosad, chlorantraniliprole, and deltamethrin and moderate cross-resistance to acetamiprid, indoxacarb, milbemectin and spiromesifen. The synergists piperonyl butoxide (PBO) S-benzyl-O,O-diisopropyl phosphorothioate (IBP) and diethyl maleate (DEM) increased the resistance 2.03-, 2.33- and ˂1.00-fold, respectively. Crossing experiments revealed that acequinocyl resistance in the ACE6 population was intermediately dominant and polygenic. Additionally, in the ACE6 population, cytochrome P450 monooxygenase (P450) and esterase detoxifying enzyme activities increased 2.40-fold and 1.85-fold, respectively. These results indicated that P450 and esterase were important enzymes in the development of acequinocyl resistance in the ACE6 population. •We obtained an acequinocyl-resistant Phytoseiulus persimilis population (RR 32.75-fold) (ACE6 population) which selected with acequinocyl.•Resistant population developed low resistance to spinosad, chlorantraniliprole, deltamethrin and moderate cross-resistance to acetamiprid, indoxacarb, milbemectin and spiromesifen.•PBO and IBP synergists increased the efficiency of acequinocyl in the ACE6 populations of the Phytoseiulus persimilis.•Acequinocyl resistance was found to lack dominance (partial dominance) and be polygenic in Phytoseiulus persimilis.•P450 monooxygenase and esterase enzymes can be considered important in the development of acequinocyl resistance population.