Detoxifying Enzyme Activities in the Common Pistachio Psylla and the Coccinellid Predator

The common pistachio psylla, Agonoscena pistaciae Burckhardt and Lauterer (Hem: Aphalaridae) is one of the main and most destructive pests of pistachio orchards in Iran. Chemical control is a widely applied method to manage this pest problem. The intensive use of insecticides has led to the development of resistant populations of the common pistachio psylla. In this research, the activities of detoxifying enzymes (general esterase, glutathione S-transferase and cytochrome P_450) were assessed against two populations of the common pistachio psylla, and the coccinellid predator, Oenopia conglobata L. (Col: Coccinellidae) in Kerman Province, under treatment of three rational insecticides, namely, acetamiprid, spirotetramat, and hexaflumuron in four concentrations (control, LC_25, LC_50 and LC_75). The results indicated that the activities of detoxifying enzymes were higher in the resistant population of psylla compared to the susceptible one. Esterase was the predominant detoxifying enzyme in the pest and its predator. Based on the results, the activity of detoxifying enzymes were higher at the higher concentrations of the pesticides. Esterase activity was greater in the psyllid populations than the coccinellid predator; which may indicate a higher sensitivity of the lady beetle to insecticides than its prey.