Food and the spatial distribution of adult female pinworms parasitic in the hindgut of Periplaneta americana L.

Food and the spatial distribution of adult female pinworms parasitic in the hindgut of Periplaneta americana L. International Journal for Parasitology 4: 759–771. The spatial distribution of the two pinworms Hammerschmidtiella diesingi and Leidynema appendiculata in the adult cockroach Periplaneta americana was determined by examination of hind guts fixed by immersion in liquid air. The position of the mouths of the worms reveals that L. appendiculata favours a more anterior position and is more restricted in its distribution than H. diesingi. The position of each species in the colon is unaffected by the presence of the other species or by crowding. Moreover, the two species are segregated in terms of their radial distribution, with the mouth of H, diesingi being restricted to a position near the intima of the colon while that of L. appendiculata favours the lumen. The two nematodes differ in the structure of the stoma and pharynx which reflect a difference in their diet. The food of L. appendiculata consists of relatively large particles while that of H. diesingi is finely patticulate. The ability of these two species to coexist in the same host is explained by their longitudinal and radial distribution and by the different sources of their food.