Gazangabin is excreted by Gavan psyllid. In this Study the psyllid species together with their distribution were investigated. Psyllid insects were sampled when on Astragalus adseendens as host plant. Sampling sites were specified at every 30 to 40 Km. on 1: 250000 and 1: 50000 maps, samples being collected by using beat traps. The number of nymphs and adult psyllids were counted for each sample with the sampling sites then categorized. According to this index all sampling sites were determined on a province map using ILWIS 2.1 Software. Results showed that in addition to Cyamophila dicora Login as the dominant species, Bactericera nigricornis also feeds on A. adscendens. This new species has not been reported before because of its low population and limitd distribution. Gaz psyllid had the highest density in Fereidoonshahr and Golpayegan and lowest in Khansar and Chadegan. In other areas the density lied in between. This insect was not observed in Shahreza and Semyrom. From among 24 locations investigated, the insect was not found in 11 places with its population being very low in other areas, confirming the gradual extinction of the insect on Astragalus adscendens in these areas.
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