Feeding ecology of outbreak insect species

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The long term objective of my research program is to better understand the role of food and its chemical composition on insect defoliator fitness and population dynamics and to determine the impacts of food quality variations on the co-evolution patterns between trees and insect defoliators in the context of rapid changing environments due to climatic change and human manipulation of forest ecosystems. During the period covered by the current proposal, I will use eastern spruce budworm on balsam fir and black spruce as a model system and I will determine the impact of variations in nutrients and allelochemicals on insect performance not only during the feeding period but also during the rest of its life cycle, including during winter diapause. In addition, I will continue the study over four successive generations. Cohorts of spruce budworm fed artificial low and high nutritive quality food as well as cohorts of insects fed high nutritive quality foliage from undefoliated trees (foliage characteristic of low density budworm populations) and low nutritive quality foliage from previously defoliated trees (foliage characteristic of high density budworm populations) will be followed during four successive generations in a reciprocal transfer experimental design and under various winter conditions. The reciprocal transfer experiment approach will allow detection of local adaptation to food deterioration by partitioning genetic and inherited environmental components of offspring phenotype. Inherited environmental effects (parental effect) are those components of the phenotype that are derived from either parent, apart from nuclear genes. Although environmental effects are inherited (like money) they are not heritable. By placing diapausing progeny along a latitudinal gradient and in growth chambers with various winter temperature regimes, I will be able to explore the interactions between parental food quality and progeny winter conditions within the context of climatic changes.