大螟蔗田枯心苗的空间分布型及抽样技术研究

Spatial distribution pattern and sampling technique of dead heart seedlings by the pink stem borer Sesamia inferens in sugarcane fields

为了确定大螟蔗田枯心苗的空间分布型与抽样技术,采用聚集度指标法、Iwao回归分析法和Taylor幂法则分析了甘蔗枯心苗的空间分布型,根据Iwao的理论抽样数模型确定了蔗田枯心苗的最适理论抽样数。甘蔗枯心苗的空间分布呈聚集分布,基本成分是个体群,个体间相互吸引,个体群在蔗田呈聚集分布。聚集程度随密度的升高而增加,聚集原因可能是由于甘蔗自身特性和大螟为害等环境因子作用或其中一个原因引起的。5种抽样方法均可用于蔗田抽样调查。用Iwao的理论抽样数模型计算出蔗田枯心苗的理论抽样数模型为:D=0.1时,n=230.470 0/m+0.980 0,D=0.2时,n=57.617 5/m+0.245 0,D=0.3时,n=25.607 8/m+0.108(m为枯心苗平均密度)。本文为开展大螟测报和防治提供了理论依据。

The spatial distribution pattern and sampling technique of dead heart seedlings by the pink stem borer Sesamia inferens （Walker） in sugarcane fields were studied to provide the basis for forecasting and control of S. inferens. The spatial distribution pattern of dead heart seedlings of sugarcane was examined by aggregation indi- ces, Iwao^s regression and Taylor indices, and the sampling number for dead heart seedlings of sugarcane was ob- tained by the mathematical model of Iwao theoretical sampling. The dead heart seedlings of sugarcane had an ag- gregated distribution pattern, and the basic element of distribution was the individual colony in sugarcane fields. Individuals attracted each other, and individual colonies were thus aggregately distributed. The distribution pat- tern of dead heart seedlings got more and more aggregative as its density increased, and the aggregated distribution was caused by the characteristics of sugarcane and environmental factors, such as the damage of S. inferens. Five sampling methods could be used in sugarcane fields. The theoretical sampling formula for dead heart seedlings of sugarcane was established as followed： n=230. 4700/m＋0. 9800（D=0. 1）, n =57. 617 5/m＋0. 2450（D=0. 2） and n=25. 607 8/m ＋00. 108 9 （D=0.3）（m in the average density of dead heart seedling）. The spatial distribution pattern of dead heart seedlings by S. inferens in sugarcane fields was aggregated distribution, and five sampling methods could be used in sugarcane fields.