The Role of Host Traits, Season and Group Size on Parasite Burdens in a Cooperative Mammal

Abstract

The distribution of parasites among hosts is often characterised by a high degree of heterogeneity with a small number of hosts harbouring the majority of parasites. Such patterns of aggregation have been linked to variation in host exposure and susceptibility as well as parasite traits and environmental factors. Host exposure and susceptibility may differ with sexes, reproductive effort and group size. Furthermore, environmental factors may affect both the host and parasite directly and contribute to temporal heterogeneities in parasite loads. We investigated the contributions of host and parasite traits as well as season on parasite loads in highveld mole-rats (Cryptomys hottentotus pretoriae). This cooperative breeder exhibits a reproductive division of labour and animals live in colonies of varying sizes that procreate seasonally. Mole-rats were parasitised by lice, mites, cestodes and nematodes with mites (Androlaelaps sp.) and cestodes (Mathevotaenia sp.) being the dominant ecto- and endoparasites, respectively. Sex and reproductive status contributed little to the observed parasite prevalence and abundances possibly as a result of the shared burrow system. Clear seasonal patterns of parasite prevalence and abundance emerged with peaks in summer for mites and in winter for cestodes. Group size correlated negatively with mite abundance while it had no effect on cestode burdens and group membership affected infestation with both parasites. We propose that the mode of transmission as well as social factors constrain parasite propagation generating parasite patterns deviating from those commonly predicted.

Ectoparasite diversity in the eastern rock sengis (Elephantulus myurus): the effect of seasonality and host sex

“…Increases in mite abundance with rainfall have previously been reported for several other mite species in South Africa irrespective of whether rainfall occurs during winter (Matthee et al 2007;Archer et al 2014) or summer (Viljoen et al 2011) as in the current study. Unlike R. warburtoni/arnoldi the abundance of Ixodes spp.…”

Ectoparasite Burdens of the Common Mole-Rat (Cryptomys hottentotus hottentotus) From the Cape Provinces of South Africa

“…The low number of species found does appear to be a typical pattern for mole-rats based on previous studies that have investigated the ectoparasites of bathyergids (De Graaff, 1964, 1981Viljoen et al, 2011). This impoverished endoparasite fauna may be a result of limited parasite exposure in the subterranean habitat of such rodents (Rossin et al, 2010;Viljoen et al, 2011). We cannot exclude the possibility that our sampling approach might have missed additional ectoparasites and that the lack of ticks encountered in this study is partially attributable to animals being sampled several days after capture.…”

“…Most of these species have been collected in previous studies on mole-rats referred to as C. hottentotus (De Graaff, 1964, 1981. The low number of species found does appear to be a typical pattern for mole-rats based on previous studies that have investigated the ectoparasites of bathyergids (De Graaff, 1964, 1981Viljoen et al, 2011). This impoverished endoparasite fauna may be a result of limited parasite exposure in the subterranean habitat of such rodents (Rossin et al, 2010;Viljoen et al, 2011).…”

“…Ectoparasites that have developmental stages that live off the host are thought to be particularly susceptible to effects associated with the surrounding habitat (Vinarski et al, 2007;Krasnov, 2008). However, no taxon-specific pattern is apparent, and although some studies have shown that lower levels of humidity can reduce the abundances (Krasnov, 2008;Viljoen et al, 2011), others have found the opposite pattern (Fabiyi, 1996;Matthee et al, 2007).…”

“…Although well studied with regard to their social system and reproductive physiology, studies investigating their parasite fauna remain scarce, and only a limited number of hosts have been sampled (Scharff et al, 1997;Tenora et al, 2003;Viljoen et al, 2011). This is particularly true for their ectoparasite fauna, and several parasitological studies of bathyergid species state explicitly that they did not find any ectoparasites (De Graaff, 1972;Scharff et al, 1997).…”