Morphological Study of Digestive Cycle in Bloodsucking Biting Midges of Genus Cu1icoides

Changes in the midgut of biting midges Culicoides punctatus (Mg.) and C. grisescens (Edw.) in the course of digestion of the single blood portion were studied using methods of light and electron microscopy. Essential differences are shown in structure of intestinal epithelial cells of young non-fed females and adult individuals completing each digestive cycle. Blood digestion in adult females of both species takes about 3.5–4.0 days and is not accompanied by formation of blood thrombus. Formation of the peritrophic membrane occurs at the period of 12 h to 2.5 days after blood-feeding and is associated with secretory activity of cells of the posterior part of midgut. Functions of secretion, absorption, and transport of substances are performed by all cells of intestinal epithelium and to the great extent are overlapped in time. Peculiarities of structural organization of digestion in midges in comparison with other blood-sucking insects are discussed.__________Translated from Zhurnal Evolyutsionnoi Biokhimii i Fiziologii, Vol. 41, No. 2, 2005, pp. 176–185.Original Russian Text Copyright © 2005 by Filimonova.