Relationship Between Helminth Parasites and Demographic Attributes of a Population of the Subterranean Rodent Ctenomys talarum (Rodentia: Octodontidae)

Abstract

The helminth parasite fauna of a natural population of the octodontid, Ctenomys talarum, was studied. Parasites that were found included the nematodes Heligmostrongylus sp. and Trichuris sp. Total prevalence of parasitism was 92.3%, mean intensity of infection was 22.7 worms, and mean abundance was 21 worms. Prevalence and mean abundance of infection with Heligmostrongylus sp. were higher in C. talarum males relative to females. Ecological and physiological causes, as well as the mating system of the host species, influence the likelihood of sex differences in parasite infection. The low parasite burden and diversity of C. talarum are associated with restrictions imposed by the subterranean habitat and with life-history traits of these rodents. Whether these findings apply to other Ctenomys spp. is unknown.

Determinants of Helminth Infection in a Subterranean Rodent, the Cape Dune Mole-Rat (Bathyergus suillus)

“…Extrinsic factors such as rainfall and temperature, on the other hand, often act on the parasite directly, resulting in variation in the spatial and temporal distribution of parasites (Poulin, 2007). Such extrinsic factors and, as a consequence, the distribution of parasites often differ between habitats, and, accordingly, habitat use can determine the exposure of hosts to parasites (Froeschke et al, 2010).It has repeatedly been noted that the subterranean niche of fossorial rodents may limit their exposure to parasites, and this has been linked to the low parasite species richness encountered in a number of subterranean rodents (Gardner, 1985;Hafner et al, 2000;Rossin and Malizia, 2002;Rossin et al, 2010). Rodents from a range of families have adapted to a subterranean lifestyle, and, despite their diverse origin, they show remarkable similarities with respect to morphology, physiology, and basic life history traits.…”

“…It has repeatedly been noted that the subterranean niche of fossorial rodents may limit their exposure to parasites, and this has been linked to the low parasite species richness encountered in a number of subterranean rodents (Gardner, 1985;Hafner et al, 2000;Rossin and Malizia, 2002;Rossin et al, 2010). Rodents from a range of families have adapted to a subterranean lifestyle, and, despite their diverse origin, they show remarkable similarities with respect to morphology, physiology, and basic life history traits.…”

“…However, efforts have been made, and studies on the North American geomyids, the South American octodontids, as well as the European spalacines have reported a number of cestodes, nematodes, and coccidian parasites for these rodents (Gardner, 1985;Hafner et al, 2000;Rossin and Malizia, 2002;Rossin et al, 2010). Most of these studies are of a taxonomic nature (Rossin and Malizia, 2002;Rossin et al, 2010). The southern African bathyergids, or mole-rats, are another very specious family of subterranean rodents (Bennett and Faulkes, 2000).…”

“…Since only 4 hosts were sampled in June, while otherwise the minimum sample size per mo was 15 (mean ± SE: 34.0 ± 3.97), we pooled the data for June and July for analyses. To allow comparisons with the results obtained by Rossin et al (2010) for Ctenomys species, we defined 3 sex categories: males, non-pregnant females, and pregnant females. However, unlike Rossin et al (2010), we did not use body condition as it was confounded for pregnant females, and, consequently, it differed significantly between pregnant and nonpregnant females (t 5 24.484, df 5 171, P , 0.0001).…”

“…To allow comparisons with the results obtained by Rossin et al (2010) for Ctenomys species, we defined 3 sex categories: males, non-pregnant females, and pregnant females. However, unlike Rossin et al (2010), we did not use body condition as it was confounded for pregnant females, and, consequently, it differed significantly between pregnant and nonpregnant females (t 5 24.484, df 5 171, P , 0.0001). Since body mass was significantly correlated with body length in non-pregnant individuals (R S 5 0.911, n 5 283, P , 0.0001), we included body length as a variable for the analyses.…”