Scavengers often feed on diets that are poor in some of the essential nutrients required for growth and development. This includes cockroaches, which as a group are primarily scavengers feeding on dead organic matter. Cockroaches supplement dietary deficiencies by hosting an endosymbiont bacteria, Blattabacterium. Cockroaches have had these endosymbionts for over 140 million years. The Blattabacterium live in special cells in the abdomen of the cockroach in a metabolic tissue known as the “fat body”. The Blattabacterium gets access to a steady supply of nutrients, protection from the vagaries of the environment and are passed from mother to offspring.
The success of the Blattabacterium is tied to the success of its cockroach host (they long ago lost the ability to be free living). The Blattabacterium takes a waste product from the cockroach, uric acid, and uses it to produce amino acids that are essential for the growth and development of both Blattabacterium and the cockroach. Unlike other insects that secrete uric acid as a waste product, cockroaches excrete very little. Male cockroaches have even been known to transfer uric acid to female cockroaches as a “nuptial gift” during mating.