STUDIES ON THE ECOLOGICAL NICHE WIDTH AND OVERLAP OF THE POPULATIONS BETWEEN THE RICE PLANT HOPPER AND THEIR PREDACEOUS NATURE ENEMIES

The ecological niche widths and overlaps of the time and space for the populations between the rice plant hoppers and their preda-ceous nature enemies from the rice fields were tested. The popuala-tions tested included: Nilaparvala lugens, Sogatela furcifera, Micraspis discolor, Paederus fuscipes, Microvelia horvathi, Hydrometa albolineata. Cyrtorrhinus tividipemis, Erigonidiumm graminicolum, Theridium octoma-culaium, Tetragnatha iaponica, Lycosa pseudoannulata, Bianar hotingchlehi. The result showed that the timal and spatial niche widths of the populations, Nilaparvala lugens and Sogatela furcifera, were smaller than that of the others. The timal and spatial niche width indecated the limitaion of the activities for the two populations during the rice growing. When the timal and spatial niche widths of the rice plant hopper populations were similar to that of the predaceous nature enemy populations, the good environment for the predaceous nature enemies controling the rice plant hoppers were formed. The larger valus of the timal and spatial niche overlaps between the pests and the enemies exist in the pairs between N. lugens and E. graminicolum, N. lugens and C. tividipemis, S. furcifera and C. tividipemis indicating the relationships between them are clossed. If both timal and spatial niche overlaps of the populations between the pests and the enemies were large in the same time, the efficiency for the enemies preying on the pests would be hight.