Metabolic Fuel Reserves in the Stable Fly (Diptera: Muscidae)1

Abstract

Changes in triacylglycerol and glycogen content were studied throughout the life cycle of the stable fly, Stomoxys calcitrans . Both triacylglycerol and glycogen were found to be utilized for embryogenesis. The larvae accumulated triacylglycerol and glycogen as they grew and these reserves reached a maximum at pupation. Greatest larval development occurred between the 3rd and 5th day. During this period, triacylglycerol and glycogen levels increased at least 20 fold and 9 fold, respectively. Nearly 95% of the glycogen and about 50% of the triacylglycerol reserves were utilized during pupal-adult transformation, indicating that some lipids are spared for use during early adult life. Adult flies accumulated large quantities of lipids after blood feeding, with maximum amounts noticeable after the 3rd and 5th blood meals in male and female flies, respectively. However, glycogen levels in adult flies showed little variation throughout the investigation. Considerable reserves of triacylglycerol and glycogen are stored in developing ovaries. Before the end of the 1st gonotropic cycle the ovaries contained nearly 18% and 20% of total triacylglycerol and glycogen reserves of the whole insect.