Gross Anatomy and Histology of the Alimentary System of the Larva of Palm Weevil, Rhynchophorus Phoenicis Fabricius (Coleoptera: Curculionidae)

The gross anatomy and the histology of the alimentary tract of the larva of palm weevil, Rhynchophorus phoenicis were described in this study. The results showed that the alimentary system of the insect has three distinct parts, the foregut, midgut and hindgut. In the foregut are oesophagus, crop and proventriculus (gizzard). The crop was the biggest part of the alimentary system, suggesting that the larva consumes big amount of food. Muscular proventriculus was present at the base of the foregut and it is the place where the food of the larva is pulverized. The midgut was the longest part of the alimentary tract. The anterior portion of the midgut is located in the thoracic region while the distal part which is coiled is embedded in the abdominal segments. The midgut epithelium is characterized by columnar cells, goblet cells, villi, microvilli, cappilaries and peritrophic membranes. The membrane helps to protect the midgut cells from damage from abrasive food particles. The hindgut forms the posterior part of the alimentary system and it consists of the ileum and rectum which terminates in the anus. There no villi but temporary folds of submucosa and mucosa layers. There are adipose cells, goblet cells, intestinal glands, circular and longitudinal muscles in this region.