Host-Parasite Relationships of Helminth Parasites in Leeches of the Genus Haemopis. II. Associations at the Host-Species Level

Publisher Website
Google Scholar
Abstract
Specimens of 5 spp. of mature enteric trematodes, an unidentified tetracotyle, 2 spp. of nematodes, 1 enteric and 1 parenteric, and unidentified glossiphonid leeches were recovered from necropsies of 189 specimens of 6 spp. of haemopid leeches collected from Iowa and Minnesota [USA] 1976-1979. Statistical analysis indicated that populations of all helminths were significantly overdispersed in their hosts and that the negative binomial distribution provided an adequate fit to most of the observed parasite frequency distributions. Estimated values of the parameter k were < 1.0 and, in several cases, they approached zero. The significance of this extreme aggregation of parasites and its possible consequences at the suprapopulation level are discussed. Species-specific differences in habitat and dietary preferences of different species of hosts are compared with observed patterns of prevalence and density of helminths of haemopid leeches reported here and in the literature. H. grandis, H. plumbea and H. marmorata are primarily aquatic. H. lateromaculatum and H. kingi are semiaquatic. H. lateralis is confined to terrestrial habitats. Dietary diversity, helminth faunal diversity and relative density of helminths all appeared to decrease with the increase of terrestrial habits in the hosts. An ecologic hypothesis is proposed to explain species-specific differences in the dynamics of haemopid parasites on the basis of habitat and dietary relationships evolved by the different species of hosts.