Documenting the rules that organisms use to prioritize resource allocation between life history traits is essential to understanding plasticity in life histories. The last larval-adult molt is a critical life history transition in insects and provides an excellent system for studying priority rules. At eclosion, resources accumulated by larval feeding can be allocated to two major life history parameters: somatic growth, and the resultant adult body size, or nutrient storage for use in adulthood. I investigated patterns of plasticity and priority rules for resource allocation between somatic growth and nutrient storage in insects by determining the effects of resource limitation on allocation to these two traits at the last larval-adult molt in the grasshopper, Schistocerca americana. Larval diet had a significant effect on allocation to somatic growth. An intermediate nutrient content diet supported the best growth. Across diets, larger individuals contained more stores, but when somatic growth was held constant, there was a significant effect of larval diet only on lipid content. Individuals exhibited resource-based plasticity in allocation to lipid storage, but no other storage parameter. Individuals fed the best growth diet allocated proportionally more resources to lipid stores than individuals fed the poorest diet. On low nutrient content diets, larvae prioritized allocation to body size whereas individuals on intermediate nutrient content diets grew larger and allocated more to lipid stores. This suggests that larvally derived lipid stores play some role in adult fitness in S. americana, but that body size is even more important.
Species 1: Orthoptera Acrididae Schistocerca americana (American Locust)
Keywords: Lipid Storage, Phenotypic plasticity
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