The common pistachio psylla, Agonoscena pistaciae, is a major pest of the pistachio trees, which is supposed to be con- sisted of many allopatric populations. Since psyllids, including A. pistaciae, have close associations with various obligate mutualists and facultative symbionts, the study was conducted to determine the diversity of bacterial endosymbionts asso- ciated with four psyllid populations viz., Feizabad, Neyshabour, Kerman and Khash. Psyllids were evaluated for their gut endosymbionts through PCR amplifications with their specific primers. The sequences were subjected to a BLAST search to find most similar sequences in GenBank. Our findings disclosed the presence of ‘Candidatus Carsonella ruddii’ (primary endosymbiont), Wolbachia, and Hamiltonella (secondary endosymbionts). There were no infection of Serratia in the pistachio psyllid populations. ‘Ca. Carsonella ruddii’ showed a 100% infection frequency in populations and Wolbachia, Arsenopho- nus and Hamiltonella indicated 50, 15 and 20% infection frequencies, respectively. The rate of infection with Wolbachia, Arsenophonus and Hamiltonella ranged from 40 to 70%, 0 to 40% and 10 to 30%, respectively. The current study furnished an insight into endosymbiont variation in the pistachio psyllid populations; nonetheless, more investigations are required to assess their probable impacts on the fitness of their psyllid host.

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