Dictyocaulus infection

A. Danks, Hannah, Sobotyk, Caroline, N. Saleh, Meriam, Kulpa, Matthew, L. Luksovsky, Joe, Jones, Lee C & Verocai, Guilherme G., 2022, Opening a can of lungworms: Molecular characterization of Dictyocaulus (Nematoda: Dictyocaulidae) infecting North American bison (Bison bison), International Journal for Parasitology: Parasites and Wildlife 18, pp. 128-134 : 133-134

4.4. Potential impacts of Dictyocaulus infection in bison

Studies in cattle show that subclinical D. viviparus infections can cause significant losses in milk production, with a reduction ranging from 1.01 to 1.68 kg /cow/day of milk ( Dank et al., 2015). Dank et al. (2015) also demonstrated that cows with subclinical D. viviparus infections produced milk with 0.14% less milk fat, potentially reducing growth in calves. Dictyocaulosis has been also associated with reduction of yearly calf survival and weakening of individuals in cattle ( Panuska, 2006; David, 1999). Currently, the impact of Dictyocaulus infection in North American plains bison is unknown, although previous reviews suggest that subclinical or clinical disease may develop in infected individuals managed under high density production models ( Haigh et al., 2002; Berezowski et al., 2018). While dictyocaulosis could cause direct economic impact to the bison industry, the effects on wild herds managed at low densities on natural range are likely minimal, and especially if our newly identified species of Dictyocaulus evolved in North American plains bison. In contrast with many production management models, wild bison health is determined by the resilience and sustainability of this species to native pathogens and parasites ( Stephen, 2014; Jones et al., 2020).

4.5. Future explorations of the historical biogeography of Dictyocaulus in North American bison

The substantial genetic divergence of North American plains bison Dictyocaulus isolates in relation to those found in cattle and European bison allows us to infer on its historical biogeography. Assuming B. bison bison is the primary host for this species, one would expect a deeper association with this wild bovine species – the larger remnant bovine in the Nearctic fauna. The genus Bison arrived in North America through the Bering Land Bridge in two waves: one 195-135kybp (thousand years before present) and another 45-21kybp in the Pleistocene Epoch, likely as Bison priscus . This species later evolved into Bison latifron s, and later as Bison antiquus and Bison occidentalis with the latter existing until 1730ybp (Froese et al., 2017; Zver et al., 2021). According to fossil records, B. bison only appeared around 10kybp within the Holocene, and is currently subdivided into two subspecies, the plains bison, B. b. bison , and the wood bison, B. b. athabascae ( Heintzman et al., 2016; Geist, 1991). To explore beyond our identification of this distinct Dictyocaulus species in North American plains bison, sampling of wood bison and additional plains bison herds may further elucidate the geographic distribution of this lungworm. Moreover, a deeper understanding of the phylogeography of this newly identified Dictyocaulus may be attained by means of comparative mitogenome and whole genome sequencing and

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molecular clock analysis ( Gasser et al., 2012; McNulty et al., 2016).