Effects of high-fat diet on development in Manduca sexta

Nutritionally-balanced diets are important for fitness, but for insects the high energy value of fat storage is crucial for reproduction and development. Although studies have focused on carbohydrate and protein intake, little is known about how insects regulate fat consumption when presented with diets containing varying lipid content. Due to conserved fat metabolism pathways in vertebrates and invertebrates, better understanding the role of lipids in insects could contribute to knowledge of human metabolic diseases and provide support for using insect models for these studies. This study investigated the effect of a high fat diet on 5^th instar Manduca sexta. When fed a diet containing either high fat (5.6% linseed oil) or low fat (0.4% linseed oil), those fed a high fat diet ate less, as indicated by a decrease in the number and mass of fecal pellets.  Caterpillars fed a high fat diet also had a lower average mass increase throughout the instar.   These results suggest that increased fat may result in cessation of feeding.  Further studies are needed to understand the mechanism of feeding regulation by dietary fat.