As the ladybug is an insect, the fat body plays major roles in their lives. The fat body is a highly dynamic tissue composed primarily of storage cells, and involved in multiple metabolic functions. One of these functions is to store and release energy in response to the energy demands of the insect. Ladybugs store energy reserves in the form of glycogen and triglycerides in the adipocytes, the main fat body cell. Insect adipocytes can store a great amount of lipid reserves as cytoplasmic lipid droplets.

 

Lipid metabolism is essential for growth and reproduction and provides energy needed during extended nonfeeding periods. This section focuses on energy storage and release and summarizes current understanding of the mechanisms underlying these processes in insects.

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According to Arrese, Estela et al (2011), the insect fat body plays an essential role in energy storage and utilization. It is the central storage depot for excess nutrients and is an organ of great biosynthetic and metabolic activity. Fat body cells not only control the synthesis and utilization of energy reserves—fat and glycogen—but also synthesize most of the hemolymph proteins and circulating metabolites.

 

Large amounts of relevant proteins, such as storage proteins used as an amino acid reservoir for morphogenesis, lipophorins responsible for the lipid transport in circulation, or vitellogenins for egg maturation, are secreted by the fat body.

 

This is where most of the insect’s intermediary metabolism takes place, which includes lipid and carbohydrate metabolism, protein synthesis, and amino acid and nitrogen metabolism. Some metabolic processes are stage specific such as the synthesis and secretion of storage proteins into the hemolymph that occur in the feeding larva or the synthesis of vitellogenin in adult insects.