Helminth species richness in wild wood mice,Apodemus sylvaticus, is enhanced by the presence of the intestinal nematodeHeligmosomoides polygyrus

Abstract

We analysed 3 independently collected datasets of fully censused helminth burdens in wood mice, Apodemus sylvaticus, testing the a priori hypothesis of Behnke et al. (2005) that the presence of the intestinal nematode Heligmosomoides polygyrus predisposes wood mice to carrying other species of helminths. In Portugal, mice carrying H. polygyrus showed a higher prevalence of other helminths but the magnitude of the effect was seasonal. In Egham, mice with H. polygyrus showed a higher prevalence of other helminth species, not confounded by other factors. In Malham Tarn, mice carrying H. polygyrus were more likely to be infected with other species, but only among older mice. Allowing for other factors, heavy residual H. polygyrus infections carried more species of other helminths in both the Portugal and Egham data ; species richness in Malham was too low to conduct a similar analysis, but as H. polygyrus worm burdens increased, so the prevalence of other helminths also increased. Our results support those of Behnke et al. (2005), providing firm evidence that at the level of species richness a highly predictable element of co-infections in wood mice has now been defined : infection with H. polygyrus has detectable consequences for the susceptibility of wood mice to other intestinal helminth species.

Possible Influence of B Chromosomes on Genes Included in Immune Response and Parasite Burden in Apodemus flavicollis

“…In their natural hosts, heligmosomoid nematodes can show a pronounced pattern of co-infection with other parasite species [4], [57], [58]. We did not observe any co-occurrence effects of studied parasite species, rather the opposite.…”

The helminth community of the wood mouseApodemus sylvaticusfrom the Erro River valley, Navarre, Spain

“…Behnke et al (2009) concluded that H. polygyrus has an effect on other co-infecting helminths in wood mice, and therefore that quantitative interactions between helminths infecting wild wood mice exist and contribute to the infracommunity structure at individual host level, and to the component community structure at population level. Thus, this nematode might play an important role in helminth community stability, explaining the high prevalence of infection detected.…”

Parasitism underground: determinants of helminth infections in two species of subterranean rodents (Octodontidae)

“…Also, pairs of significantly associated species consisted, in 3 of the 4 cases, of species living in different microhabitats within the host, suggesting that immune-mediated effects are more likely explanations than active resource competition. Recent studies have emphasized that positive interactions are as frequent, if not more frequent, than negative ones in helminth communities of rodents and other mammals (Behnke et al 2005(Behnke et al , 2009Lello et al 2004). For instance, Behnke et al (2009) have provided data suggesting that the nematode Heligmosomoides polygyrus facilitates infection of its rodent host, Apodemus sylvaticus, by other helminths by suppressing parts of its immune response.…”

“…Recent studies have emphasized that positive interactions are as frequent, if not more frequent, than negative ones in helminth communities of rodents and other mammals (Behnke et al 2005(Behnke et al , 2009Lello et al 2004). For instance, Behnke et al (2009) have provided data suggesting that the nematode Heligmosomoides polygyrus facilitates infection of its rodent host, Apodemus sylvaticus, by other helminths by suppressing parts of its immune response. In our study, 3 of 4 significant associations were positive, suggesting either some form of facilitation as in the preceding example, or that both species are acquired together in a way that generates a statistical association.…”