Abstract:

 Micromorphological examination of the gut wall of Zonocerus variegatus has shown variations in the wall structure of the crop, midgut and hindgut. The crop is folded longitudinally when empty. It is lined luminally by a cuticular layer. Behind this layer there are small polyhedral cells made into clusters by the longitudinal fold. Three to five fat bundles of striated muscles surround the crop. The midgut which consists of anterior gastric caeca, posterior gastric caeca and ventriculus is cuticle free. Its epithelium is of columnar cells with brush borders. The midgut cells were classified into regenerative, young, resting, extruding and erupting cells depending on the characteristics of their nuclei. The resting cells were the most abundant (42.59%). Anterior gastric caeca, posterior gastric caeca and ventriculus had similar cells. There was a significant difference in the thickness of the epithelia of the six nymphal stages (P<0.05), being thinner at first and second instar nymphs than third, fourth and fifth. The mean thickness of epithelia of sixth instar nymphs observed at 2 day intervals were the same. The hindgut has cuticular layer too, but the underlying epithelium is of columnar cells. The hindgut cells are therefore presumed to help in digestion and absorption of food. Storage, digestive and absorptive functions performed in the pre-hindgut region are suggested to be summarised by the hindgut activities.

Key words: Zonocerus variegates, gut, microstructural adaptation, food storage, digestion, absorption