Parasites of an Arctic scavenger; the wolverine (Gulo gulo)

Abstract

Parasites are fundamental components within all ecosystems, shaping interaction webs, host population dynamics and behaviour. Despite this, baseline data is lacking to understand the parasite ecology of many Arctic species, including the wolverine ( Gulo gulo ), a top Arctic predator and scavenger. Here, we combined traditional count methods (i.e. adult helminth recovery, where taxonomy was confirmed by molecular identification) with 18S rRNA high-throughput sequencing to document the wolverine parasite community. Further, we investigated whether the abundance of parasites detected using traditional methods were associated with host metadata, latitude, and longitude (ranging from the northern limit of the boreal forest to the low Arctic and Arctic tundra in Nunavut, Canada). Adult parasites in intestinal contents were identified as Baylisascaris devosi in 72% (n = 39) of wolverines and Taenia spp. in 22% (n = 12), of which specimens from 2 wolverines were identified as T. twitchelli based on COX1 sequence. 18S rRNA high-throughput sequencing on DNA extracted from faeces detected additional parasites, including a pseudophyllid cestode ( Diplogonoporus spp. or Diphyllobothrium spp.), two metastrongyloid lungworms ( Angiostrongylus spp. or Aelurostrongylus spp., and Crenosoma spp.), an ascarid nematode ( Ascaris spp. or Toxocara spp.), a Trichinella spp. nematode, and the protozoan Sarcocystis spp., though each at a prevalence less than 13% (n = 7). The abundance of B. devosi significantly decreased with latitude (slope = -0.68; R 2 = 0.17; P = 0.004), suggesting a northerly limit in distribution. We describe B. devosi and T. twitchelli in Canadian wolverines for the first time since 1978, and extend the recorded geographic distribution of these parasites ca 2000 km to the East and into the tundra ecosystem. Our findings illustrate the value of molecular methods in support of traditional methods, encouraging additional work to improve the advancement of molecular screening for parasites.

Wolverines (Gulo gulo) in the Arctic: Revisiting distribution and identifying research and conservation priorities amid rapid environmental change

“…Most studies of Arctic wolverine health have focused on parasitism. The species’ large territories, generalist diet, and position in regional food webs likely predispose wolverines to high overall parasitism rates, which generally exceed 80% in the Arctic and make the species a good candidate as a sentinel of landscape-level parasite spread (Watson et al 2020 ; Sharma et al 2021 ). Historical or longitudinal data of wolverine parasitism remain sparse for evaluating such trends, but information is improving.…”

“…Historical or longitudinal data of wolverine parasitism remain sparse for evaluating such trends, but information is improving. Documented parasites include several taxa of both helminths and protozoa, with > 80% taxa-specific prevalence of Trichinella spp., Taenia twitchelli , Sarcocystis spp., and Baylisascaris devosi and 40–60% prevalence of the protozoan Toxoplasma gondii in some, but not all, regions of the North American Arctic (Rausch 1959 ; Addison and Boles 1978 ; Reichard et al 2008b , a ; Dubey et al 2010 ; Sharma et al 2019 ; Watson et al 2020 ). Wolverine is the preferred definitive host for T. twitchelli , which likely uses porcupine ( Erethizon dorsatum ) as its intermediate host and therefore may be limited to the Low Arctic (Rausch 1959 ).…”

“…The single rabies case is the only Arctic wolverine mortality directly attributable to disease of which we are aware, and sublethal effects of this and other potential pathogens and toxins remain poorly understood. Most parasites found in wolverines use the species as a definitive host, which likely reduces health consequences (Watson et al 2020 ), and although several bacterial taxa known to cause disease in other species are found in wolverine, bacterial disease induction in wolverines is so far undocumented (Watson 2020 ). Toxoplasmosis and Trichinellosis in humans, typically arising from undercooked parasitized meat consumption, are increasing concerns in Arctic communities relying on subsistence hunting (Keatts et al 2021 ).…”

“…Information regarding pathogen and parasite disease potential to wolverines in the Arctic is insufficient to predict the possible impacts of such changes to the species. We therefore recommend continued monitoring of wolverine health using community-based initiatives in collaboration with hunters and trappers (Oakley et al 2016 ; Sharma et al 2019 ; Watson et al 2020 ) and study of physiological response to potential disease vectors. The connection between human and animal health in the Arctic and subarctic is increasingly recognized under the “One Health” framework (Ruscio et al 2015 ), yielding successful longitudinal monitoring efforts of wildlife health across diverse taxa (e.g., caribou, muskoxen, and ringed seal ( Phoca hispida ); Brook et al 2009 ; Tomaselli et al 2018 ; Harwood et al 2020 ); we advocate development of similar long-term efforts for wolverines.…”

Identification of Trichinella taxa by ITS-1 amplicon next-generation sequencing with an improved resolution for detecting underrepresented genotypes in mixed natural infections

“…NGS methods may enable a higher sensitivity for detecting underrepresented species in mixed infections. A growing number of published studies have described the species composition of complex parasitic nematode communities using DNA metabarcoding by deep amplicon NGS in various livestock and wildlife host species [17][18][19][20][21][22][23]. In the current study, we leveraged this NGS approach for genotyping Trichinella spp.…”