草地螟滞育性的研究

草地螟在我国部分地区有滞育现象.是影响越冬虫源分布和种群数量变动的重要原因之一.1982—1984年观察研究结果,光周期是影响滞育性的决定性条件.其临界光周期为14—15小时,最低临界点13小时,最高临界点16小时,温度是影响年度间滞育量的重要因素.以光周期划分草地螟的滞育区和非滞育区,是掌握虫源基地的重要依据.以滞育区的气温变化,分析幼虫滞育量,对展望种群数量的自然积累或衰落,即种群数量变动规律,具有重要意义.

STUDIES ON DIAPAUSE OF BEET WEBWORM

In some parts of China, the diapause ( Loxostcgc sticticalis Linnaeus) occurring in beet webworm is one of the important factors that affects the distribution of the over wintering webworm and the variation of its species group. The results observed from 1982 to 1984 showed that the light periodicity is a determinant to beet webworm diapause. The critical photoperiod is 14-15 hr., the shortest period is 13 hr.,the longest is 16 hr. .Meanwhile, the temperature is another important factor affecting the diapause quantity from year to year.We suppose that according to light periodicity, beet webworm diapause may be divided into two regions: diapause region arid non-diapause region. It provides a scientific basis for learning the place where the over wintering beet webworms come from. The diapause quantity detected in the light and temperature variation at diapause region is pracatically significant to forecast the n-atural accumulation and decline of the species group (the pattern of species group fluctuation).