Spatial distribution of Agonoscena pistaciae (Hemiptera: Aphalaridae) in Rafsanjan region
عنوان دوره: دومین کنگره بین المللی حشره شناسی ایران
نویسندگان
چکیده
The pistachio psyllid, Agonoscena pistaciae Burckhardt and Lauterer, is one of the most damaging pests of pistachio in Iran. To investigate spatial distribution pattern for eggs and nymphs of A. pistaciae, samplings were done weekly in Rafsanjan pistachio orchards, during May to September 2016. The pistachio terminal leaflets were selected as sampling unit. Number of eggs and nymphs were recorded at three canopy of tree, upper, middle and lower part. After preliminary sampling, sample size was determined as 36 units for each canopy, so that the relative variance was less than 20%. The spatial distribution pattern of eggs and nymphs of A. pistaciae was determined using mean - variance ratio, Taylor´s power low and Iwao´s patchiness regression model, and Liyod and Morista index. Based on the mean- variance ratio, the spatial distribution of eggs and nymphs was estimated, aggregated at three canopy of the tree. The slope of the regression for Taylor´s power low and Iwao´s patchiness regression model, in middle canopy of tree was significantly more than one for egg, then the spatial distribution was estimated aggregated. And in upper and lower canopy was estimated, random distribution for egg. In both Taylor´s power low and Iwao´s patchiness regression model, the slope of the regression at three canopy of the tree was significantly more than one for nymph, then the spatial distribution was estimated aggregated. Also, the results of Liyod and Morista index showed that the spatial distribution of A. pistaciae egg and nymph in the three canopy was aggregated distribution.
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