POPULATION-DYNAMICS OF APODEMUS-AGRARIUS PALLAS AND ITS ECONOMIC THRESHOLD IN THE PADDY REGION

Investigations were conducted in the double or middle season paddy reg ions from 1988 to 1990; main results showed that the population of Apo demus agrarius reached maximal reproductive rate between April and May , and between September and October each year. Their maximal populatio n size occurred in July and between October and November each year. At different stages of the rice, mouse density (X) was significantly rel ated to loss rate of the rice (Y). Studies on imitation mouse damage o n rice indicated that the rice, damaged by the mice in tillering stage , possessed a certain capacity for compensation. When the mouse damage rate approached yield loss rate in the booting or spiked stage the ri ce plant lost this compensatory capacity. It will be seen from the abo ve that early spring is the most available, feasible time for mice con trol. Under the current production level the economic thresholds of mo use density are 3% in spring, 5% for early and middle-season rice and 7% for later rice.