Variation in Insecticidal Susceptibility of Agonoscena pistaciae Burckhardt and Lauterer (Hemiptera: Aphalaridae), and its Coccinellid Predator, Oenopia conglobata L. (Coleoptera: Coccinellidae)

The common pistachio psylla, Agonoscena pistaciae Burckhardt and Lauterer is a key pest throughout all pistachio producing regions of Iran. Pest management depends primarily on the application of chemical insecticides. The lack of compatibility between natural enemies and pesticides is the main concern to ecologists in the integrated management of psylla. The susceptibility of the fifth instar nymphs of A. pistaciae from five populations of the Kerman province and third instar larvae of the lady beetle species, Oenopia conglobata L., were examined against three commonly used insecticides: acetamiprid, spirotetramat and hexaflumuron, using the spraying tower method. Probit regression analysis was conducted on mortality data at various insecticide concentrations using the POLO-PLUS program to estimate LC50 values. Resistance ratio data revealed that usage of pesticides has led to resistance in the psylla population of Rafsanjan. The results showed that the Rafsanjan psylla population (with LC50 values of 40.55, 43.65 and 95.10 mg a.i. L-1, for acetamiprid, spirotetramat and hexaflumuron, respectively) was the most resistant and the Anar population (with LC50 values of 11.92, 24.13 and 81.06 mg a.i. L-1 for acetamiprid, spirotetramat and hexaflumuron, respectively) was the most susceptible based on the LC50 ratios of insecticides. The LC50 values of acetamiprid, spirotetramat and hexaflumuron for the coccinellid predator O. conglobata in the Rafsanjan population were estimated to be 8.76, 5218.33 and 2268.81 mg a.i. L-1, respectively. The predator was more susceptible to acetamiprid and more tolerant to spirotetramat and hexaflumuron than the psylla A. pistaciae.