Evaluation of Resistance Inducers in the Pistachio Trees on Population Growth and Detoxifying Enzymes of Pistachio Psylla, Agonoscena Pistaciae (Hemiptera: Psyllidae)

Pistachio psylla Agonoscena pistaciae Burckhardt & Lauterer is Iran's most important pest of pistachio trees. Due to the negative effects of excessive use of chemical insecticides, alternative strategies are necessary to control this pest. In this research, some resistance-inducing compounds, including chitosan, gamma-aminobutyric acid (GABA), and potassium silicate in pistachio trees, were studied on the percentage of population growth and detoxifying enzymes of this psyllid. Based on the results obtained, 7 days after spraying, the lowest and highest population growth of pistachio psyllid nymphs were observed in chitosan treatment and control, respectively. Also, the average growth percentage of the nymph population after 14 days did not show a significant difference among GABA, chitosan and potassium silicate, but it significantly decreased on these treatments compared to the control. In this study, the highest and lowest activity levels of esterase enzyme in psyllid nymphs were achieved in the control and chitosan treatments, respectively.On the other hand, the highest level of glutathione S-transferase activity was obtained in chitosan and potassium silicate treatments, and the lowest one was found in the control. The study results revealed that the different inducers could reduce the A. pistaciae population growth by generating physiological changes in the host plant and, subsequently the pest insect. Therefore, these compounds could be considered in the integrated management of this pest.