بررسی تغییرات جمعیت و پراکنش فضایی سنک عناب Monosteira alticarinata (Hem., Tingidae) در شهرستان بیرجند

The jujube, Ziziphus jujuba Mill. is a well-known medicinal plant with various nutritional values and pharmacological properties which grows in South Khorasan province. In order to study the population fluctuations and spatial distribution of M. alticarinata, sampling was done weekly in jujube orchards of Birjand region (South Khorasan province) from the start of crop season to end of it in 2020. Jujube leaf was selected as sampling unit. To investigate the population fluctuations, 200 leaves from 10 selected trees (20 leaves from each tree) were randomly collected from different geographical directions and transferred to the laboratory in plastic bags, and the number of different biological stages was counted using a stereomicroscope. The Pearson correlation coefficient was used to determine the relationship between lace bug density and temperature and relative humidity as variables. To determine the spatial distribution of M. alticarinata, the reliable sample size with maximum relative variation of 20% was obtained 50. The number of egg, nymph and adult was recorded in three heights of jujube trees (1.5, 2, and 3 meters). The spatial distribution pattern of different life stages of lace bug was determined using mean-variance ratio, Lloyd's mean crowding index, Taylor´s power low and Iwao´s patchiness regression model. The results of population fluctuations showed that the highest population density of eggs, total nymphs and adults of M. alticarinata were average 394.3±69.09, 114.4±20.5 and 42.4±6.92 in 15/08/2020, 05/09/2020 and 01/08/2020, respectively. A positive and significant correlation was observed between jujube lace bug total population density (r= 0.527, P=0.005) with temperature, however, the correlation was negative and non-significant for relative humidity (r= -0.274, P=0.167). The spatial distribution pattern of different life stages of M. alticarinata was aggregated in all heights of jujube. The parameters derived from population fluctuations and the spatial distribution pattern of this species can be used in the sampling program and estimates of population density of this pest in jujube orchards.