POPULATION ABUNDANCE AND SEASONAL ACTIVITY OF OLIGONYCHUS AFRASIATICUS (MCGREGOR) AND ITS PREDATOR STETHORUS GILVIFRONS (MULSANT) IN BAM REGION, IRANArezoo Payandeh, Azita Dehghan, Reza Kamrani, Nader Modafe Behzadi and M.R.Yavarzadeh
The population densities and spatial distribution pattern of Oligonychus afrasiaticus (McGregor) and its prey Stethorus gilvifrons (Mulsant) were determined in four date palm orchards in Bam, a southern province of Iran, from 1th May to early September, 2011. Population density of the phytophagous mites and its predator were counted on 64 fruits with its pinnae (sampling unit) weekly. The highest population density of O. afrasiaticus and S. gilvifrons were recorded in 15th (7 August) and 16th (14 August) sampling week, respectively. Spatial distribution pattern O. afrasiaticus and S. gilvifrons was described using variance to mean ratios, Taylors power law coefficient and Iwaos patchiness regression methods. Distribution pattern was aggregated for O. afrasiaticus and random distribution for its predator were used. The collected data had better fit to Taylors model for O. afrasiaticus and S. gilvifrons (r2 = 0.942 and 0.973, respectively) in comparison with Iwaos model (r2 = 0.912 and 0.862, respectively). Spatial distribution coefficient of the tetranychoid mites and its predator could be used to improve sampling programs and to estimate the population densities and the efficacy of the predator being used in orchards IPM.
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