摘要
摘要:高比例和多样的非耕作生境带来的农田景观高异质性是维持农业生物多样性的关键，推测提高非耕作生境组成能够促进农田中玉米螟天敌数量和种类增加。为揭示不同非耕作生境组成对玉米螟天敌数量的影响，本文选取东北平原玉米种植典型县——辽宁省昌图县，按照5个非耕作生境比例（0~10%、10%~20%、20%~30%、30%~40%和40%~50%）选取20个直径为600 m的样区。陷阱法采集玉米螟天敌，并用体视显微镜鉴别到科。主成分分析法筛选主要非耕作生境类型，逐步回归模型对非耕作生境组成（比例和类型）与玉米螟天敌数量进行拟合。并采用"赤池信息准则（AIC）"模型筛选，评估不同非耕作生境组成对玉米螟天敌数量的影响。研究结果表明，随着非耕作生境比例增加，玉米螟天敌数量呈先增后减的趋势，非耕作生境比例为20%~30%时天敌数量达最大值。非耕作生境比例20%~30%时，非耕作生境组成与玉米螟天敌数量关系最优模型（AIC=4.24，为最小值）是Y=b₀-b₁D+b₂PC2，最优模型表明PC2（β=3.787，P=0.005）代表以林地为主的非耕作生境组成与玉米螟天敌数量呈显著正相关，景观多样性指数D（β=-3.173，P=0.005）与玉米螟天敌数量呈显著负相关。该比例的非耕作生境组成与玉米螟天敌数量关系的其他模型表明，以草地和村落为主（PC1）的非耕作生境与玉米螟天敌呈显著正相关（β=1.957，P=0.000）。而其他比例下，所有关系模型说明农田周边林地生境和其他作物耕地有利于提高农田中天敌数量。最适宜玉米螟天敌聚集的非耕作生境比例为20%~30%，以林地为主或村落、草地为主的非耕作生境，以及分布有其他作物的耕作生境能够提高玉米螟天敌数量。研究结果可为今后从景观生态角度构建适宜非耕作生境组成来防治玉米螟提供理论依据和方法。
关键词:农业景观/
非耕作生境/
玉米田/
玉米螟/
天敌
Abstract:The agricultural landscape with high proportion and diversity of non-cropped habitats is the key to maintaining agricultural biodiversity. It is a hypothesis that the natural enemy population and types of corn borer could increase by complex and high composition of non-cropped habitats in cornfields. To clarify the relationship between non-cropped habitats proportion and natural enemy, this study investigated the effects of composition of non-cropped habitats on natural enemy population of corn borer in Changtu County in the Northeast China Plain. Twenty plots (φ=600 m) were selected and classed into five groups based on the proportions of non-cropped habitats (0-10%, 10%-20%, 20%-30%, 30%-40% and 40%-50%). The samples of natural enemies of corn borer were collected by the pitfall trap method. The families of enemies were identified using stereomicroscope. Then principal component analysis was used to classify the main types of non-cropped habitats in the region. Stepwise regression model was used to fit relation curve of non-cropped habitat composition (ratio and type) and population of natural enemies of corn borer. Then the optimal model was selected based on the Akaike's Information Criterion (AIC) for effects of different proportions of non-cropped habitats on natural enemy population of corn borer. Results showed that natural enemy population of corn borer increased at first and then decreased with increasing proportion of non-cropped habitats. Natural enemy population of corn borer was highest[with the optimal model of AIC_{minimum value}=4.24, Y=b₀-b₁D + b₂PC2, PC2 (β=3.787, P=0.005)] when the proportion of non-cropped habitats was 20%-30%. This optimal model implied that there was significant positive correlation between natural enemy population of corn borer and the composition of non-cropped habitats dominated by woodland. There was also significantly negative correlation between natural enemy population of corn borer and the landscape diversity index D. Other models[PC1 (β=1.957, P=0.000)] for 20%-30% proportion of non-cropped habitats implied that significant positive correlation existed between natural enemy population of corn borer and the composition of non-cropped habitats dominated by grassland and village. Under other proportions of non-cropped habitats, the optimal models suggested that corn filed neighboring woodland or other crops fields was beneficial for increase of natural enemy population of corn borer. In conclusion, the study showed that natural enemy population of corn borer was highest when the proportion of non-cropped habitats was 20%-30%. Non-cropped habitats dominated by woodland, grassland, village or in intercropped patterns attracted natural enemies of corn borer in farmlands with different proportions of non-cropped habitats. The study further provided theoretical basis for the prevention and control of corn borer by ways of landscape ecology.
Key words:Agricultural landscape/
Non-cropped habitat/
Corn field/
Corn borer/
Natural enemy



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