ABSTRACT
The macroparasites Cephenemyia trompe (Modeer) and Hypoderma (= Oedemagena) tarandi (L.) (Diptera: Oestridae), Linguatula arctica Riley, Haugerud and Nilssen (Pentastomida: Linguatulidae), Elaphostrongylus rangiferi Mitskevich (Nematoda: Protostrongylidae), and abomasal nematodes (Nematoda: Trichostrongylidae) were sampled in semidomestic reindeer calves (Rangifer tarandus (L.)) (ca. 8 months of age) in northern Norway in 1988 (n = 160) and 1989 (n = 191). Each parasite showed an aggregated (clumped) distribution among the hosts and fitted the negative binomial distribution. Analyses of interspecific associations in intensities showed that there was no consistent covariation among the parasites apart from a weak correlation (Kendall's tau 0.104, P = 0.007) between the 2 oestrids C. trompe and H. tarandi. This lack of covariation reveals that the parasites were distributed independently of each other, and suggests that innate host resistance is not a dominant factor that has a significant simultaneous effect on all parasites. The aggregated distribution of each parasite species is hypothesized to be caused by (1) random events and heterogeneities in host behaviour that create unequal transmission (exposure) rates, or (2) by heterogeneities in parasite specific immunocompetence among host individuals. Factors in hypothesis (1) are probably the most important at low transmission rates.
Subject(s)
Arthropods/growth & development , Diptera/growth & development , Nematoda/growth & development , Parasitic Diseases, Animal/parasitology , Reindeer/parasitology , Abomasum/parasitology , Analysis of Variance , Animals , Arthropods/immunology , Binomial Distribution , Diptera/immunology , Feces/parasitology , Female , Male , Nematoda/immunology , Norway/epidemiology , Parasite Egg Count/veterinary , Parasitic Diseases, Animal/epidemiology , Parasitic Diseases, Animal/immunology , Prevalence , Reindeer/immunologyABSTRACT
The Pentastomida, or tongue worms, form an aberrant group of annulated endoparasites little known to most parasitologists and veterinarians. Although there is no doubt of their affiliation to arthropods, textbooks often rank the Pentastomida as a separate phylum. Riley's many publications on the group have 'promoted it from the realm of the completely unknown to the semi-obscure', but still much research is needed on their basic biology, as little is known about their biochemistry, ecology or their evolutionary relationships. This review by Rolf Haugerud is intended to inspire curiosity about the Pentastomida by discussing their evolution in relation to their phylogeny, host relationships, geographic distribution, transmission and impact.
