人工固沙区景观格局变化对沙生植物害虫-天敌的影响及生态学效应

The effect of landscape changing process on biodiversity is currently a very active research field in Ecological Biology. Exploring the ecological effects of desert landscape pattern changing on population dynamics of both pests insect and their natural enemies is fundamental for ecological regulation and insect pests management in practice. Taking the region of artificial sand fixation as experimental fields in desert landscape of Ningxia, Northwest China, and through using the principles and methods of entomology and landscape ecology, three subjects are designed in the present scheme. First, through investigate how the patch pattern affect the community structure of psammophytes pests insect-natural enemies system, study how the landscape heterogeneity affect the trophic nutritional relationships of this system, we want to explore the mechanisms underlies pest insect and natural enemies interaction driveled by landscape composition, and explore the mechanisms in which landscape pattern affect pests insect-natural enemies system as well. Second, based on the grade hierarchy theory and scale effect, we want to study the landscape key factors, niche differentiation and resources division measures that affecting psammophytes pests insect-natural enemies system, thus reveal the mechanisms underlying pests natural controlling made by landscape factors. Third, through studying the ecological and behavior mechanisms of the interaction and competition both the interspecific and intraspecific relationships of common pest insect and their natural enemies, we want to explore the ecological mechanisms of pest controlling through the collective use of natural enemies at the landscape level, and also aim to reveal the pathways and methods that controlling pests emergence used by artificial sand fixed environment conditions in practice.

景观变化过程对生物多样性的影响是当前非常活跃的一个研究领域。明确人工固沙过程中景观格局的演变对沙生植物害虫及其天敌种群的生态学效应，是开展区域性害虫生态调控治理的基础。本项目以宁夏中东部荒漠景观人工固沙区为试验区，通过研究人工固沙植物斑块格局对沙生植物害虫-天敌群落结构的影响，景观异质性对沙生植物害虫-天敌三级营养关系的影响，探讨景观组成驱动天敌与害虫之间相互作用的规律，揭示景观格局影响沙生植物害虫-天敌的作用机制；将等级层次理论与尺度效应相结合，研究影响沙生植物害虫-天敌种群的关键景观因子、生态位分化和资源分割利用策略，揭示景观因子对害虫的自然控制作用机制。通过对沙生植物共有害虫种群及其天敌昆虫种内、种间互作与竞争的生态学规律和协同控害的行为机制研究，在景观水平上揭示天敌昆虫控制害虫的生态学机制，在实践上达到探索人工固沙环境条件控制害虫发生的途径和方法。

人工固沙过程中景观格局的演变对沙生植物害虫及其天敌种群的生态学效应是开展区域性害虫生态调控治理的基础。本项目以宁夏中东部荒漠景观人工固沙区为试验区，研究了人工固沙植物斑块格局对沙生植物害虫种群的发生、天敌多样性的影响，探讨了景观异质性对沙生植物害虫-天敌三级营养关系的影响等，结果表明：（1）在斑块格局下，沙生植物害虫的种群发生存在边缘效应；景观破碎化在一定程度上能降低害虫的危害率，但天敌对害虫的控制作用也会减弱。（2）沙生植物种子害虫-寄生性天敌三个营养级在生物量上呈现典型的生态金字塔形；模型检验显示上行控制效应和下行控制效应在沙生植物种子害虫-寄生性天敌营养级均存在，但前者作用更为明显；赤池信息准则评估模型显示柠条种子害虫、天敌不同，其食物网参数的最优尺度不同，非柠条生境在小尺度下（100-200m）对其互作丰度具有显著性影响；景观异质性可以提高天敌的多样性，增强对害虫的控制作用。（3）沙蒿木蠹蛾的种群密度及有虫株率受景观异质性影响明显，沙蒿株高和冠幅、土壤含水量、酸碱度是影响沙蒿木蠹蛾幼虫种群密度及有虫株率的关键生态因子；赤池信息准则评估模型显示在一定尺度阈值下（500m）复杂生境界面其种群发生要严重于简单生境界面，景观破碎化可以有效地降低其种群的发生。（4）沙蒿金叶甲呈斑块状聚集分布，幼虫在空间分布位置存在显著差异，随着龄期的增加由中上部逐渐向中下部转移。（5）豆荚螟的局域种群在不同年际间占据不同斑块的情况不同，基本满足集合种群的条件。研究结果在理论上对于揭示害虫-天敌关系的生态学机制，在实践上达到探索人工固沙环境条件控制害虫发生的途径和方法具有重要的意义。