关键词: 棉铃虫, 卵, 地理信息系统, 地统计学, 空间分布, 动态

Abstract: In this study, Geographic Information System (GIS) technology and geostatistics (GS) methods were used to analyze the spatial structure and simulate the spatial distribution with the historical data of the 2nd generation eggs densities of Helicoverpa armigera （Hübner）, which were collected from 36 monitoring points in Hebei Province during 1980 to 1997. The study areas lie in central and southern part of Hebei Province, and amounted to 93 539 km², about 51.5% of the whole provincial area. Results showed that the eggs were correlated spatially In the study areas, but degrees of correlation were all lower and different from year to year and area to area. Proportion of spatial variation changed from 3.54% to 61.67%; the distance range of spatial dependence varied from 115.92 to 487.08 km. The time series analysis showed that the quantity of H. armigera was always in fluctuation during 1980 to 1997. During the period of 1980 to 1991, the quantity was low with average density of 330 eggs per a hundred plants, and its range was 122-706 eggs per a hundred plants. However, the egg quantity became high remarkably during 1992 to 1997 with average density of 1 877 eggs per a hundred plants, and its range was 264-4 023 eggs per a hundred plants. Based on the outbreak map of the 2nd generation of H. armigera, it was found that the spatial distribution patterns were aggregated in all years, but the collective degree was changed with time and the proportion of the spatial correlation component. The density grades of egg distribution were high in the southwest, but low in the northeast in the study areas. From the northeast to the southwest, the densities of eggs increased gradually. The highest grades of density were found in the areas of Fuping, Quyang, Xingtang, Lingshou, Pingshan, Handan, Cixian, Linzhang and Weixian, and the lowest in Zunhua, Yutian, Fengrun, Tangshan and Fengnan. The density of eggs was not only related to location, but also to time. On the whole, outbreak was the heaviest in 1992 and heavier in 1993 and 1995, while moderate in the 1981 and 1990 and the lightest in 1987. The outbreak number in the 1980s was significant lower than that in the 1990s. The results were consistent with that of the time series analysis. Based on the pertinent reports and our study, It was suggested that the higher air temperature, especially warmer winter was the main factor which triggered outbreak of the H. armigera in the 1990s. It was also suggested that in west and southwest outbreak areas, numerous mountains, abundant vegetation, higher wheat cultivation proportion, and lesser rainfall in June, should be important factors leading to the outbreak of H. armigera.

Key words: Helicoverpa armigera, eggs, geographic information system, geostatistics, spatial distribution, dynamics