Details of the digestive system in the midgut of Coptotermes formosanus Shiraki

Abstract

Wood-feeding termites have evolved an efficient cellulose-decomposing system. The termite has two independent cellulose-digesting systems: one in the midgut and the other in the hindgut. Because the digestion system in the midgut should be the sole source of soluble sugars for the host termite, the details of the decomposition of wood particles in the midgut were clarified in one of the most common pest species, Coptotermes formosanus. The spatial distribution of cellulase in the midgut was found by immunohistochemistry, and the amount of endogenous cellulases and the volume of the endoperitrophic space were determined. The size of wood particles in the foregut and the midgut were compared. The results showed that one of the characteristics of wood degradation by termites is the mechanical grinding of food by the mandibles and the cuticular apparatus of the foregut. This process greatly increases the surface area of the substrates. Extremely high concentrations of cellulase attack the ground-up wood in the midgut, and the glucose produced is removed quickly through the peritrophic membrane.