The helminth infracommunities of the wood mouse (Apodemus sylvaticus) two years after the fire in Mediterranean forests

Abstract

SummaryParasites have been recognized as indicators for natural or man-induced environmental stress and perturbation. In this article, we investigated the role of two non-exclusive hypotheses on the response of helminths of wood mice to fire perturbation: 1) a reduction of the helminth infracommunity (species richness) in post-fire areas due to the temporal lack of worms with indirect (complex) life cycles linked to intermediate hosts that are more specialized than the final host, and 2) an increase of the abundance of helminths with direct (simple) life cycles as a response of increasing abundances of the final host, may be in stressful conditions linked to the post-fire recolonization process. We studied the helminth infracommunities of 97 wood mice in two recently burned plots (two years after the fire) and two control plots in Mediterranean forests of NE Spain. Species richness of helminths found in control plots (n = 14) was twice large than in burned ones (n = 7). Six helminth species were negatively affected by fire perturbation and were mainly or only found in unburned plots. Fire increased the homogeneity of helminth infracommunities, and burned plots were characterised by higher dominance, and higher parasitation intensity. We found a gradient of frequency of occurrence of helminth species according to life cycle complexity in burned areas, being more frequent monoxenous (66.6 %), than diheteroxenous (33.3 %) and triheteroxenous (0 %), confirming the utility of helminths as bioindicators for ecosystem perturbations. Despite the short period studied, our results pointed out an increase in the abundance and prevalence of some direct life cycle helminths in early postfire stages, whereas indirect life cycle helminths were almost absent. A mismatch between the final host (that showed a fast recovery shortly after the fire), and the intermediate hosts (that showed slow recoveries shortly after the fire), was responsible for the loss of half of the helminth species.

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

“…Fourteen helminth species were found in this study, a number equal to or higher than those reported in other studies (Portolés et al, 2000;Torres et al, 2003;Fuentes et al, 2004a, b;Torre et al, 2013) but lower than those reported by Fuentes et al (2007aFuentes et al ( , 2010 for various enclaves of the Iberian Peninsula.…”

Wildfire‐induced short‐term changes in a small mammal community increase prevalence of a zoonotic pathogen?

“…In the shortterm, forest fires significantly reduce richness of helminths in the long-tailed field mouse Apodemus sylvaticus Linnaeus, increase prevalence of monoxenous (life-cycle restricted to a single host species) helminths but decrease prevalence of heteroxenous helminths (life-cycle dependent on multiple host species; Torre, Arrizabalaga, Feliu, & Ribas, 2013). The latter response is likely caused by intermediate hosts being rare or absent in intensively burnt forests (Torre et al, 2013). Habitat disturbance by off-road vehicles and habitat fragmentation are associated with high prevalence of Sin Nombre virus (SNV) in deer mice and an increased encounter rate among hosts is the suggested mechanism (Langlois, Fahrig, Merriam, & Artsob, 2001;Mackelprang, Dearing, & Jeor, 2001).…”

“…Disturbances also have major impacts on pathogen prevalence in wildlife, but it remains inconclusive if disturbance increases or decreases prevalence, transmission among animals, and/or potential transmission to and infection risk of humans. In the short‐term, forest fires significantly reduce richness of helminths in the long‐tailed field mouse Apodemus sylvaticus Linnaeus, increase prevalence of monoxenous (life‐cycle restricted to a single host species) helminths but decrease prevalence of heteroxenous helminths (life‐cycle dependent on multiple host species; Torre, Arrizabalaga, Feliu, & Ribas, ). The latter response is likely caused by intermediate hosts being rare or absent in intensively burnt forests (Torre et al, ).…”

Syphacia muris infection delays the onset of hyperglycemia in WBN/Kob-Lepr fa rats, a new type 2 diabetes mellitus model

“…To investigate connection with this disease, infections with pinworm S. muris, a ubiquitous nematode that parasitizes mainly in the large intestines of wild and experimental rats (Rattus norvegicus), was employed. The lifecycle of S. muris is direct, and host animals are infected with the nematode via an oral intake of their eggs; the prepatent period of this nematode is 7−8 days (Stahl, 1961;Taffs, 1976;Torre et al, 2013). In the present study, 100 S. muris eggs were orally administered to 5-week-old fa/fa rats at the pre-diabetic stage, and eggs were detected 2 weeks after inoculation in the perianal region of all fa/fa rats in the infection group.…”