Spatial and temporal distribution of Eotetranychus frosti and Cenopalpus irani and their predator Typhlodromus bagdasarjani in an unsprayed apple orchard at Khorramabad, Western Iran

The spatial and temporal distribution of Eotetranychus frosti (McGregor), Cenopalpus irani Dosse, and their dominant predator Typhlodromus bagdasarjani Wainstein & Arutunjan were studied in an unsprayed apple orchard in Chaghalvandi region (Lorestan Province, Iran) during 2012. The population densities of these phytophagous mites and their predator were monitored from 3th May to 4th November 2012. For this purpose, samplings were done 17 times and at each of them, mite counts were made on 60 leaves (i.e. sampling unit). The spatial distribution pattern of E. frosti, C. irani and T. bagdasarjani was determined by using Taylor’s power law method. Calculated RV (relative variation) and reliable sample size for the 25% variation from preliminary sampling for E. frosti were 16.22% and 53.86, respectively. The results demonstrated that population fluctuations of E. frosti and T. bagdasarjani passed through two peaks whereas C. irani had only one peak. The highest densities were observed on 23th August (28.68 per leaf), 11th September (28.88 per leaf) and 11th August (1.18 per leaf) for E. frosti, C. irani and T. bagdasarjani, respectively. The slopes of Taylor's power law were significantly greater than 1 indicating aggregated spatial distributions in the E. frosti and C. irani, but T. bagdasarjani had b= 1, indicating random distribution. Our findings disclosed a positive correlation between population fluctuations of the two phytophagous mites and the predator, indicating a density-dependent reaction of predator to prey densities. The relationship between meteorological parameters and the three mite populations studied showed that the effect of temperature was insignificant, whereas the effect of relative humidity was significantly negative.