Seasonal and taxonomic variation in arthropod macronutrient content

Physiological regulation of internal body composition is critical for the fitness of many organisms. Arthropods are abundant around the world and exhibit incredible diversity, yet little is known about how these groups differ in body composition or the mechanisms behind internal changes in chemistry over time. The goal of this study was to examine the lipid and protein content of several common terrestrial arthropod orders, and to determine if this macronutrient composition changes across the season. Additionally, we describe relationships between arthropod body measurements and lipid, protein, and overall dry mass. Arthropod total length and width strongly correlated with macronutrient masses, while other body measurement relationships varied considerably. As expected, arthropod orders varied significantly in both lipid and protein content. Within-order lipid and protein content also varied significantly across the season. These results demonstrate that the nutritional content of invertebrates may fluctuate over time, likely due to shifts in size, ontogeny, and environmental conditions. Understanding the mechanisms behind these changes will be important for unraveling the evolutionary history of these groups as well as the roles they play in surrounding food web structure.