小麦不同生育期地下害虫为害程度与其虫口密度的关系

Relationship between the population density of ground pests and degree of damage

为明确小麦不同生育期地下害虫为害程度与其虫口密度的关系,采用棋盘式10点取样法,在调查秋播前麦田地下害虫种类和数量的基础上,研究冬前秋苗期和春季返青拔节期地下害虫为害造成的麦苗死亡率。在陕西武功,秋播前麦田地下害虫有20种,其中以金针虫和蛴螬为优势种,分别占地下害虫发生总量的58.66%和21.91%。地下害虫为害引起的死苗现象主要发生在冬前秋苗期,供试5块田的死苗率达4.4%～9.1%;春季返青拔节期的死苗率较低,仅为1.0%～2.3%。相关分析表明,地下害虫为害造成的冬前秋苗期和春季返青拔节期死苗率与其虫口密度密切相关。

To evaluate the relationship between the population density of underground insect pests and degree of damage on the host, insect pest species and population number of each species were examined before wheat being sowed in autumn. Meanwhile, wheat seedling death rates at different development sta- ges were investigated using chessboard sampling method in Wugong, Shaanxi Province. A total of 20 soil insect pest species were found in the tested wheat fields before wheat being sowed in autumn. Wireworms and grubs were the dominant pest species, up to 58.66% and 21.91% of all the soil insect pests, re- spectively. Soil insect pests resulted in the higher seedling death rate from 4.4% to 9.1% during fall- seedling stage than that from 1.0% to 2.3% during turning-green stage. Correlation analysis showed that seedling death rates caused by soil insect pests were significantly correlated with their population densities at both fall-seedling and turning-green stages.