Feeding ecology of outbreak insect species

田间和室内饲养试验结果表明，冷杉树叶总单宁可能是云杉对云杉幼虫的抗性机制。然而，所涉及的具体单宁及其个别作用方式仍有待调查。我推测，特定的叶单宁通过干扰幼虫的食物利用过程而协同作用，影响幼虫的生存和生长，并且这些特定的单宁对芽孢杆菌幼虫有不同的作用模式。这一假设将通过重量、行为、电生理和组织学研究对人工饲料中添加不同水平和从叶中提取的纯化学物质组合饲养的幼虫进行验证。根据局部适应假说，长寿植物种群内营养、防御或物候学特征的空间异质性构成了适应单个寄主表型的短命专化食草动物种群。我推测，暴发期间的食物质量恶化(由连续的昆虫落叶引起的寄主表型的变化)对芽孢子虫种群施加了选择压力，从而改变了种群的基因频率，进而导致对恶劣饲养条件的更好适应。在实验室条件下，将利用滞育后的兄弟姐妹和受损林的新鲜叶子或未受损林的叶子，在连续四代昆虫上进行相互转移实验。云杉芽孢子虫的生物学性能将被记录下来，并进行定量遗传分析。还将进行额外的实验室饲养实验，使用高质量和低质量的饲料，以调查营养胁迫对云杉幼虫几代人的影响所涉及的过程。我推测，通过选择性压力，几代施加在云杉芽孢子虫身上的营养胁迫改变了幼虫的发育和食物利用，改变了最佳营养平衡，并对积极和消极的食物质量变化(营养物质和次要化合物)做出了反应。

Results from field and laboratory rearing experiments indicate that total tannin fraction of balsam fir tree foliage appears to serve as mechanisms of host resistance to spruce budworm. However, the specific tannins involved and their individual mode of action remain to be investigated. I hypothesize that specific foliar tannins act synergically to influence larval survival and growth by interfering with larval food utilization processes and that these specific tannins have different modes of action on budworm larvae. This hypothesis will be tested using gravimetric, behavioral, electrophysiological, and histological studies on larvae reared on artificial diet supplemented with various levels and combinations of pure chemicals extracted from foliage. According to the local-adaptation hypothesis, the spatial heterogeneity in nutritive, defensive, or phenological traits within populations of long-lived plants structures populations of short-lived, specialized herbivores into demes (genetically different populations) adapted to the phenotypes of individual hosts. I hypothesize that food quality deterioration (change in host phenotype caused by successive insect defoliation) during an outbreak exerts a selective pressure on budworm population that changes gene frequency of the population which in turn leads to a better adaptation to poor feeding conditions. Reciprocal transfert experiments will be conducted over four successive generations of insect under laboratory conditions using postdiapausing siblings and fresh foliage from damaged stands or foliage from undamaged stands. Spruce budworm biological performances will be documented and quantitative genetic analysis performed. Additional laboratory rearing experiments will be conducted using high and low quality diets to investigate the processes involved in the impact of nutritional stress on spruce budworm over several generations. I hypothesize that, through selective pressure, nutritional stress imposed on spruce budworms over several generations modifies larval development and food utilization, optimal nutrient balance and responses to positive and negative food quality changes (nutrient and secondary compounds).