STUDY ON THE DISTRIBUTION PATTERN OF EGG-MASS POPULATION OF RICE STRIPED BORER (CHILO SUPPRESSALIS WALKER ) IN RICE FIELDS
Huang Hanwen, Li Yunbi, Kuang Xingquan, Zhang Guo'an(Huazhong Agricultural University ,Wuhan)
Field surveys were conducted in 1983 and 1984 in Wuchang region, Hubei province, to evaluate the distribution pattern of egg-mass population of rice striped borer, Chilo suppressalis Malker, in rice seedling fields and paddy fields. With the areas of approximate 4.50m~2 and 6.25m~2 as the cardinal quadrants of rice seedling and paddy fields respectively, the observations shown that the distribution pattern varied with egg-mass densities. Based on the regression analysis of mean-crowding (m) /mean-density ( m ) on meandensity(m), it was obtained that when egg-mass density was lower than 0.962 and 0.897 egg-masses per quadrant in seedling and paddy fields respectively,the population was aggregatedly distributed, and beyond the above densities, the population would tend gradually to random distribution.The factors which cause the egg-mass population aggregated vere also discussed in this present paper.