Abstract
Dietary fatty acids (FAs) are essential macronutrients affecting animal fitness, growth, and development. While the degree of saturation of FAs usually determines the level of absorption and allocation within the body, the utilization of dietary FAs across the life stages of individuals remains unknown. We used three different 13 C labeled FAs, with a different saturation level (linoleic acid (18:2), oleic acid (18:1), and palmitic acid (16:0)), to investigate the absorption and allocation of dietary FAs across the life stages of the Oriental hornet. Our results show that only larvae utilized all tested FAs as metabolic fuel, with palmitic acid being oxidized at the highest rate. Oleic and palmitic acids were predominantly incorporated into larval tissues, while oleic acid dominated pupal tissues. In contrast, linoleic and oleic acids were predominantly incorporated into adult tissues. These findings highlight a life stage-dependent shift in certain FAs utilization, with palmitic acid mostly utilized in early stages and linoleic acid in adulthood, while oleic acid remained consistently utilized across all life stages. This study emphasizes the importance of considering FA saturation and life stage dynamics in understanding FA utilization patterns.