Characterization of the alimentary canal and Malpighian tubules of Chrysolina herbacea (Duftschmid, 1825) (Coleoptera: Chrysomelidae): Anatomical and histological approaches

The mint beetle or green mint beetle, Chrysolina herbacea, is one of the most important insect pests of mint herb. These insects are associated with plants belonging to the Lamiaceae family, in particular the Mentha genus. They cause serious damages to plants by consuming their leaves. For this reason, it is an important agricultural pest, and the structure of the digestive system must be known well to combat these insects. The alimentary canal of adult C. herbacea divided into three main regions: foregut, midgut and hindgut. The foregut is characterized by the following parts; pharynx, esophagus, crop, and proventriculus. The proximal part of Malpighian tubules joins with the pyloric valve. Their distal parts are located in the hemocoel and have a wavy appearance and a flat surface. Malpighian tubules are surrounded by a single layer of cubic epithelium which is with brush border, and sheath. The hindgut is formed the following regions; pyloric valve, ileum, colon and rectum. In foregut and hindgut, the layers represented from within out are: intima, epithelium, muscle layer. In the midgut, the layers from within out are: peritrophic membrane, epithelium, muscle layer. The foregut has a monolayer cubic epithelium with oval nuclei. In the midgut, the epithelium is simple columnar while in the hindgut, the epithelium is simple cuboidal. This is the first report on alimentary canal and Malpighian tubules histo-anatomy in C. herbacea. The results will help guide the development of new strategies for managing this pest.