PHYSID SNAILS AS SENTINELS OF FRESHWATER NEMATOMORPHS

• Published in: The Journal of parasitology 2001-10, Vol.87 (5), p.1049-1053
• Main Authors: Hanelt, B, Grother, L. E, Janovy Jr, J
• Format: Article
• Language: English
• Subjects: Adults; Animal, plant and microbial ecology; Animals; Aquatic environment; Aquatic insects; Biodiversity; Biological and medical sciences; Cysts; Ecology; Fresh Water - parasitology; Fundamental and applied biological sciences. Psychology; Gastropoda; General aspects. Techniques; Global positioning systems; GPS; Helminths - growth & development; Histocytochemistry; Humans; Infections; Insect larvae; INVERTEBRATE–PARASITE RELATIONSHIPS; Laboratories; Larvae; Life history; Life span; Methods and techniques (sampling, tagging, trapping, modelling...); Mollusks; Nebraska - epidemiology; Parasite hosts; Parasites; Population density; Rural Population; Sampling; Sampling methods; Snails; Snails - parasitology; Soils; Species; Statistics, Nonparametric; Suburban areas; Suburban Population; Urban Population; Worms
• ISSN: 0022-3395; 1937-2345
• DOI: 10.1645/0022-3395(2001)087[1049:PSASOF]2.0.CO;2

Freshwater nematomorphs, or gordiids, are parasitic as larvae, but free-living in aquatic environments as adults. Studies based on the collection of adults have reported gordiids to be widespread, but discontinuous in distribution. However, a relatively short adult life span and unknown life history make the detection of adults difficult. An alternative approach to investigate gordiid distribution is to use cysts. Of all paratenic hosts, snails were chosen because they lacked internal defense reactions to the cysts and become easily infected. Here, it is reported that the occurrence of gordiids on the basis of the cyst stage is much more common than previously reported, thus altering the perception of how common these worms are. Using this modified survey procedure, gordiid cysts were found at 70% of sites examined, in an area where extensive sampling over 3 yr yielded adults only at a single site. Of 1,000 snails dissected, 395 were infected with gordiids (intensity range: 1–465). Furthermore, different types of human-modified landscapes did not affect gordiid distribution, suggesting that as urban and suburban areas sprawl, human encounters or pseudoparasitism with nematomorphs may increase. The results of this study indicate that use of organismal-specific sampling techniques can be critical in studies of parasite distribution and biodiversity.