Vol. 37 No. 2, 1998
Morphology and Ultrastructure of the Alimentary Canal of Oriental Fruit Fly Bactrocera dorsalis (Hendel) (Diptera: Tephritidae) (I): The Structure of the Foregut and Cardia
Wen-Yung Lee*, Mei-Er Chen and Tai-Lang Lin
Institute of Zoology, Academia Sinica, Taipei, Taiwan 115
Wen-Yung Lee, Mei-Er Chen and Tai-Lang Lin (1998) The foregut and the cardia of Bactrocera dorsalis
(Hendel) were investigated by light microscopy and transmission
electron microscopy. The foregut of this fly is comprised of a tiny
slender tube, the oesophagus, and a lateral diverticulum of the crop.
The crop provides a long, smooth duct opening near the end of the
oesophagus, and a sac located in the anterior part of the abdomen. The
oesophagus and the crop have a thick cuticle (the intima), a thin and
simple epithelium, a basement membrane and it is surrounded by a
well-developed visceral circular muscle. The cardia is located between
the foregut and the midgut, and includes the midgut epithelium in the
outer portion of the cardia and the foregut epithelium in the inner
portion. The oesophageal epithelium extends into the cardia to form the
cardial valve. Both the longitudinal and the circular muscles beneath
the oesophageal epithelium form a sphincter to control the entrance of
food to the midgut and prevent the regurgitation of the midgut
contents. The peritrophic membrane is secreted and forms from the
surface of microvilli of the midgut at the anterior part of the cardia.
Key words: Oesophagus, Crop, Cuticle, Epithelium.
*Correspondence: Tel: 886-2-27899526. Fax: 886-2-27858059.