草地螟的有效积温及其世代区的划分

THE THRESHOLD TEMPERATURE, THERMAL CONSTANT AND DIVISION OF GENERATION REGIONS OF MEADOW MOTH (LOXOSTEGE STICTICAL1S L.) IN CHINA

经实验测定,草地螟(Loxostege sticticalis L. )各虫态的发育起点温度:卵为14.3℃、幼虫为12.7℃、蛹为11.6℃、成虫为11.0℃;有效积温:卵为30.5日度、幼虫为190.7日度、蛹为158.3日度、成虫为96.7日度。全世代的发育起点温度为10.5℃,有效积温为531.2日度。虽然草地螟各虫态的理论发育起点温度和实测值尚有一定差异,但根据上述结果推算的发生世代数目和实际发生世代数目基本一致。根据对草地螟发生地区的有效积温计算和实际观察记载,草地螟在我国的发生世代数目表现为由南到北递减的趋势。在年等温线0℃以北地区每年发生1代,年等温线0—8℃地区年生2—3代,年等温线8—12℃地区年生3—4代。草地螟在我国的主要为害区是2—3代区,主要为害世代是第一代。

The threshold temperature and thermal constant of various stages of the meadow moth (Loxostege sticticalis L.) were determined in the laboratory. The threshold temperatures for egg, larva, pupa, adult and whole generation were 14.3℃, 12.7℃, 11.6℃, and 10.5℃, and thermal constants for them were 30.5, 190.7, 158.3, 96.7 and 531.2 day-degrees, respectively. Although the calculated values of threshold temperature were somewhat different from the values actually measured, the number of predicted generation based on above results were consistent wkh those actually observed in various geographic regions in China.According to the computation of thermal constants, the generation number of meadow moth occurred annually appeared decreasing with the increasing of latitude. There was annually 1 generation in the areas northern to the annual isotherm line of 0℃, 2-3 generations to 0-8℃, and 3-4 generations to 8-12℃. Analysis of population dynamics of the meadow moth in va-rious regions revealed that this insect caused damage mostly in the 2-3 generation region by the first generation occurring from May to July.