Abstract: Based on analysis of interaction between the yellow stem borer (YSB), Scirpophaga incertulas (Walker) and its host rice, ecological mechanism for homeostasis of the insect population in its successive generations was investigated. The result showed that yearly pattern of the moth occurring durations among generations a year was similar although dynamics of their number was different in Wujin County, Jiangsu Province and Hexian County, Anhui Province with distinct rice cropping systems. Duration of the 2nd generation moth in the field was always ≥27 days, much longer than that of the 1st generation in different years. The duration increment mainly resulted from different developing rates of larvae even in the plants of the same rice variety, with an extreme stage difference of 3 instars after the neonates infesting into the rice for 20 days. The asynchronous development of YSB larvae in the host led to the evidently increase in temporal niche of the population by 22.0%～75.0%, which counteracted the decrease of its spatial niche due to the larval mortality. Consequently dualdimension niche of the population expanded by 15.1%～59.3%. The asynchronous development also made it feasible to mate between the offsprings of the earliest and the latest occurring moths, so as to produce a combined type of YSB. It was probable that homeostasis of the YSB population was genetically kept by the combined type and its offsprings which would avoid genetic drift of the population in extreme climates such as a earlier emerging spring. Finally, the strategy and key techniques for systematic management of YSB population in both quantity and quality of YSB population have been established and well practiced in certain areas on the basis of these researches.

Key words: Scirpophaga incertulas, population homeostasis, ecological mechanism, systematic management