Types and Chemistry of Diets

The knowledge of diets and their chemical components demanding digestion is a prerequisite to understanding the evolution of insect midguts. The clade Insecta is a hyper-diverse group, and this diversity extends to an impressive number of different feeding habits. Therefore, we can only summarize some of the most conspicuous and representative types of diets used by insects in their natural environments. The diversity of chemical compounds found in these diets is also staggering. This makes insects excellent models for investigating the comparative physiology of digestion among animals. The following diets will be discussed: detritus, plant exudates, other plant material, animal flesh, blood, fungi, lichens, bacteria, and nectar. In this chapter, we will discuss some of the major types and chemical compositions of diets used by insects. Our focus will be on chemical constituents that require some special type of digestion or that offer some challenge that leads to adaptations in the insect digestive system.