玉米螟赤眼蜂的寄生卵块在玉米上的田间分布型

玉米螟赤眼蜂是松辽平原玉米带寄生亚洲玉米螟卵的优势种。通过几年来的田间释放结果,取得优异的成效。通过对它在玉米田间的分布型研究,揭示了它在玉米田间第一代螟卵发生期间的分布规律,为以疏松的寄生卵块集团形式呈聚集分布;集团内寄生卵块的分布是随机的,无论在高密度时,还是在一般密度条件下,均为聚集分布型;它不受风向的影响。这一研究结果为它的田间释放和应用技术提供重要的科学依据。

SPATIAL DISTRIBUTION PATTERNS OF TRICHOGRAMMA OSTRINIAE PARASITISM IN THE EGG MASSES IN CORN FIELDS

The present paper deals with the spatial distribution patterns of Trichogramma ostriniae parasitism in the egg masses in corn fields. Based on the analysis of the data obtained from a preliminary survey, several methods were used to test the distribution pattern of T. ostriniae and the structure of its spatial distribution. These methods are: the comparative method of freguency distribution, the aggregated index method, the Iwao method and the Taylor method. The results are as follows:1.By measuring and testing the distribution pattern of egg masses parasitized by Trichogramma ostriniae in four plots of corn field under different conditions, down wind and up wind, we found that all were of the aggregated distribution patterns. The direction of the wind did not influence the field distribution patterns of the parasitized eggs. It only influenced the distance and range of the dispersal of T. ostriniae.2.The results from all data showed that during the first generation of the corn borer in Gong Zhuling region, the eggs parasitized by T. ostriniae were mainly of aggregated distribution pattern of loose egg mass community (individual community); the distribution of eggs in the community was at random.3.The results also showed that when the population density was high or each of the plants bore multiple egg masses, an aggregated pattern would occur; when the density was moderate or each of the plants bore two egg masses, the distribution was also essentially aggregated.