Suitable habitat of Therioaphis trifolii population on arable lands of southern Ningxia based on GIS

Based on GIS techniques,the interpolation maps of Therioaphis trifolii population on the arable lands in Yuanzhou District of Guyuan City in different periods were overlapped with the ecological regionalization map and digital altitude map,aimed to analyze the relations of T.trifolii population density with its ecological environment and geographical distribution.In the study area,the occurrence and distribution of T.trifolii had close relations with climate,geomorphology,and altitude.The suitable habitat of T.trifolii in the District was located in the semi-arid plain area and semi-arid holly area at the altitude 1440-2000 m,while the most possible occurrence area was the semi-arid plain at the altitude 1600-1800 m.By combining the suitable habitat with the interpolation maps of T.trifolii population in different periods,the spatial dynamics of T.trifolii population in variety of ecological areas could be analyzed quantitatively.