بررسی مشخصه‌های زمین‌آماری جمعیت شته haris acyrthosiphon pisum در مزارع یونجه شهرستان‌های دزفول (خوزستان) و بروجرد (لرستان)

تجزیه‌های زمین‌آماری به‌عنوان یک روش جایگزین برای بررسی مشخصه‌های مربوط به داده‌های بوم‌شناختی متغیرهای مکانی به‌خصوص برای جمعیت حشرات کاربرد دارد. شته سبز نخود فرنگی acyrthosiphon pisum haris از مهم‌ترین گونه‌های شته در مزارع یونجه محسوب می‌شود. این پژوهش در سال زراعی 1400- 1401 در مزارع یونجه شهرستان‌های دزفول (خوزستان) و بروجرد (لرستان) به‌ترتیب با مساحت پنج و هفت هکتار (90 و 130 شبکه 25 × 25 متری) انجام شد. نمونه‌برداری از شته‌ها با استفاده از یک کادر 1 × 1 متری انجام و در هر شبکه، دو کادر به‌صورت تصادفی انداخته و از داخل هر کادر، شش ساقه و در مجموع، 12 ساقه انتخاب و شمارش شد. تجزیه و تحلیل داده‌ها با استفاده از نرم‌افزار gs+ انجام و به‌منظور مدل‌سازی تغییرات وابستگی مکانی با افزایش فاصله بین نمونه‌ها، منحنی‌های نیم تغییرنما محاسبه و ارائه شد. نتایج تجزیه‌های زمین‌آماری برای شته‌ فوق در مزارع یونجه شهرستان‌های دزفول و بروجرد نشان داد که از 22 مرحله نمونه‌برداری، 12 مورد با مدل کروی، هشت مورد با مدل نمایی و دو مورد با مدل خطی برازش داشتند. درجه وابستگی مکانی بین 0.500 تا 0.998 قرار گرفت که نشان می‌دهد بیش از 50 درصد از تغییرپذیری (واریانس) بین داده‌ها دارای ساختار مکانی هستند و ضریب تبیین بین 0.55 تا 0.98متغیر بود. الگوی پراکنش این گونه از نوع تجمعی و دامنه موثر برای این گونه، در مدل نمایی به نسبت بالا و در مدل کروی در بروجرد بین 121.9 تا 221.2 متر و در دزفول بین 137.9 تا 493.4 متر قرار گرفت. با توجه به نتایج این تحقیق، استفاده از علم زمین‌آمار و نقشه‌های پراکنش به‌منظور ردیابی و پیش‌آگاهی جمعیت در اوایل حمله شته سبز نخود فرنگی به مزارع یونجه پیشنهاد می‌شود.

investigating the geostatistical characteristics of the aphid population of acyrthosiphon pisum haris in alfalfa fields in dezful and borujerd regions

introductionacyrthosiphon pisum harris aphid is one of the most important aphid species in alfalfa fields. in the case of a large population, it directly and indirectly damages the host plants. reports have shown their presence in several regions worldwide, including iran, particularly on fodder plants and most plants belonging to the legume family. geostatistical analysis provides an alternative approach for the characterization of spatially variable ecological data, particularly for insect population. geostatistics includes two parts, variography and kriging. the foundation of geostatistics is semi-variogram, which is a variance diagram based on the distance between samples, which shows the structure of spatial relationship among the samples. kriging is one of the geostatistical methods that are used to estimate the regional variable value in different areas of the farm. regarding geostatistical estimation, the value of a quantity in areas with known coordinates is estimated by using the same quantity in other points with known coordinates. this method allows for precise estimation of the value of a local variable in areas where sampling has not been conducted. these maps can accurately predict population changes and the likelihood of reaching the economic threshold in various parts of the farm. as a result, they can be highly effective in pest management programs. materials and methodsthis research was carried out in the crop year of 2021-2022 in two three-year alfalfa fields located in two cities of dezful (khuzestan) of baghdadi variety and borujard (lorestan) of hamadani variety, with an area of ​​five and seven hectares, respectively. to record the population density of desired pest in different parts of the selected farms, the number and location of each sampling station were determined based on their length and width coordinates (in meters) were considered constant during the sampling period. to determine the location of sampling stations, first, four main directions were identified in the fields and from the southwest area of ​​the fields, and to eliminate the marginal effects of the fields, a point with coordinates (0,0) was selected two or three meters from the edge of fields. each of desired fields was divided into regular grids of 25 x 25 meters. the farms in the dezful and borujerd areas were examined, and a total of 90 and 130 sampling sites were identified and labeled with plates. the parameters of each station were recorded on these plates. the sampling started in march 2022 and lasted until mid-november 2022. to sample the population of aphids, a 1 x 1m quadrat was used in such a way that two quadrats were randomly thrown in each grid and six stems were selected from each box, and a total of 12 stems were selected and shaken inside a pan, and counted the aphids. a total of 22 sampling stages were performed. excel 2010, spss ver. 26 and gs+ version 5.1 software were used for data analysis. the data related to each station were checked for normality by helping kolmogorov-smirnov test, and if necessary, they were placed in the determined coordinates by helping one of the appropriate data conversion methods. then, variogram curves, as well as kriging maps for each sampling date were presented in the data that had the highest r2 and degree of spatial dependence.