水稻大螟为害株空间分布格局与抽样技术

为探索水稻大螟田间调查抽样技术，提高水稻大螟预报准确率，通过聚集度指标法、Iwao法和Taylor幂函数法，研究浙江北部地区水稻大螟的田间空间分布格局和抽样技术。结果表明，水稻大螟无论是第2代引起的枯心还是第3代引起的白穗，无论是田埂边还是田中间，均呈聚集分布，聚集原因由大螟本身的生物学特性与环境因素互作的结果。第2代引起的枯心有“趋边”现象，田埂边水稻比田中间容易受害，二者间差异达极显著水平，而第3代基本一致，无显著性差异。抽样数量随着为害程度的加大而递减，第2代、第3代的最适理论抽样模型分别为n2=287.83/m+38.57和n5=447.42/m+10.63。

Study on the Spatial Distribution Pattern of Damaged Rice Hills by the Seamia inferens (Walker) and a Sampling Technique

The rice pink stem borer (PSB) Seamia inferens (Walker) (Lepidoptera: Noctuidae) is a disastrous species in eastern China and other tropical South- Eastern Asian rice production regions. The lack of information regarding its spatial distribution impeded the establishment of suitable sampling techniques in field and regional scales to control its damage in rice. The numbers of damaged rice hills in 50 sampling units (0.25 m2 of rice plants) from each of 10 directly- sown rice fields were counted in the north of Zhejiang Province, China, and the aggregation index, Iwao’ s index and Taylor’ s power methods were adopted. The results showed that the space distributions of dead heart caused by larvae of the 2nd generation, and white-head caused by the 3rd generation of PSB, either nearby the boundary or in the middle of field, were found to be aggregating distribution. During the 2nd generation of PSB, rice plants near the boundary were much more seriously damaged than those in central field, which implied that PSB was attracted by rice plants near the boundary (boundary phenomenon). However, there was no such phenomenon existed in the 3rd generation. A sequential sampling equation, n2=287.83/m+38.57 and n5=447.42/m+10.63, in which n=sampling size and m= mean number of damaged hills per sampling unit, was proposed for the controlling of the 2nd and the 3rd generation of PSB, respectively.