Morphology and histology of the alimentary tract of adult palm weevil, Rhynchophorus phoenicis Fabricius (Coleoptera: Curculionidae)

Abstract

Palm weevil (Rhynchophorus phoenicis) is a notorious pest of oil palm trees, worldwide. Investigations were conducted on the alimentary tract of the adult insect. Results of the morphology and histology of the alimentary tract revealed that the alimentary tract consisted of a foregut, which was made up of a buccal cavity, oesophagus, crop and proventriculus. The crop big or small and the proventriculus had bristle teeth which the insect used in the mechanical breakdown of ingested food. The midgut is the longest part of the alimentary tract and most prominent features there are goblet cells, columnar cells, villi, microvilli and intestinal glands. The midgut was well adapted for the digestion and assimilation of food. The hindgut was responsible for the re-absorption of water from undigested food (feaces) because of the presence of rectal pads. The results of these investigations revealed that the alimentary tract of the weevil was structurally and functionally adapted to digest and extract its nutritional requirements from its food. Key words: Morphology, histology, alimentary tract, adult palm weevil, Rhynchophorus phoenicis.