Uric acid accumulation in cockroach wings

Abstract

Cockroaches, embracing some 4,500 species in the world, are found in a variety of environments including human settlements. The ecological success of cockroaches is attributable to the ability to endure long periods of starvation and to thrive on nutritionally poor diets, which is underpinned by the capability of storing their own nitrogenous waste products as uric acid in the fat body and also by the endosymbiosis with bacteriocyte-dwelling bacteria Blattabacterium that recycle the stored uric acid for synthesis of amino acids. Previous histological studies on cockroaches described that uric acid is accumulated within the fat body, especially in urocytes. Here we report that cockroaches also accumulate uric acid in the wings. In our observation of the German cockroach Blattella germanica under different nutritional conditions, we found that well-fed cockroaches exhibited whitish aggregates in the wing veins, which is ascribed to accumulation of uric acid granules. The uric acid granules in the wings disappeared by starvation and were restored by feeding in B. germanica. The uric acid granules in the wings were found not only in B. germanica but also in other diverse cockroach species.