Dermacentor Albipictus Research Articles

Prevalence of Winter Ticks (Dermacentor albipictus) in Hunter-Harvested Wild Elk (Cervus canadensis) from Pennsylvania, USA (2017–2018)

Winter ticks (Dermacentor albipictus) are an aggressive one-host tick that infest a wide-diversity of ungulates. Infestations can result in anemia, alopecia, emaciation, and death. Most notably, the winter tick has caused negative impacts to moose (Alces alces) populations in the northeast United States and Canada. Winter ticks have been identified on other cervid species, including deer (Odocoileus virginianus) and elk (Cervus canadensis), which generally results in low tick burdens and mild or no disease. Recently, however, a wild yearling bull elk in Pennsylvania was found dead as a result of severe winter tick infestation. To obtain baseline data on winter ticks in wild elk in Pennsylvania, we collected 1453 ticks from 190 hunter-harvested wild elk between 2017–2018. Of the 204 harvested elk, 94.3% (190/204) had ticks collected for this study and none of the sampled elk had evidence of winter-tick associated disease. The average tick burden was 7.7 ticks/elk and average winter tick load on all elk was 0.5. Results of this study indicate that winter ticks do infest wild elk in Pennsylvania. However, during the fall months, the tick burden is low and rarely associated with lesions. These data herein serve as a baseline to monitor winter tick populations over time.

First records of Dermacentor albipictus larvae collected by flagging in Yukon, Canada

BackgroundThe winter tick (Dermacentor albipictus) has garnered significant attention throughout North America for its impact on wildlife health, and especially for moose (Alces alces), where high tick burdens may result in host hair loss, anemia, and can prove fatal. The environmental transmission of D. albipictus larvae to a host is a critical event that has direct impact on infestation success, yet in-field observations of this life stage are lacking. In Yukon, Canada, D. albipictus had previously been found on hosts, but its larval life stage had not been detected in the field, despite previous sampling attempts.MethodsWe sampled for D. albipictus larvae using traditional flagging methods in Ibex Valley and Braeburn, Yukon. Sites were sampled repeatedly for D. albipictus larvae by flagging from late August to end of October in 2018 and late August to end of November 2019.ResultsLarvae of D. albipictus were collected throughout Ibex Valley, at approximate densities ranging from 0.04 to 4236 larvae/100 m2. Larvae were present primarily on grassy vegetation on south-facing slopes in the Ibex Valley region and in Braeburn. Highest average larval numbers suggest peak questing activity was towards the end of September and beginning of October, as elsewhere in North America.ConclusionsTo the best of our knowledge, we report the first successful collection of the off-host, larval life stage of D. albipictus by flagging, north of 60° latitude in Yukon, Canada. These new observations provide critical information on the spatial distribution of the host-seeking life stage of D. albipictus and confirm that this species is completing its whole life cycle in southern Yukon. Understanding the environmental conditions where larvae spend their vulnerable period off-host in this northern location can inform both management strategies and projections of future range expansion which may occur with a changing climate.

Recent reports of winter tick, Dermacentor albipictus, from dogs and cats in North America.

Dermacentor albipictus, a common one-host tick of large animals in North America, is most often reported from moose (Alces alces) and is rarely implicated as a parasite of cats and dogs. From 2018 to 2020, 4 dogs and 4 cats from United States and 3 dogs from Canada were infested with D. albipictus. The specimens were collected and submitted to university diagnostic specialists by veterinary clinics in Indiana, Kentucky, Minnesota, Colorado, Wyoming, Utah, Alberta, and British Columbia between the months of October to February (United States) and April to June (Canada). Six adults and five nymphal D. albipictus were collected in the United States while three adults were collected from pets in Canada, and most often a single D. albipictus was present. Identification of specimens collected in the United States were confirmed by amplification and sequencing of 16S rRNA and ITS-2 gene fragments. Rickettsia spp. were not detected in any D. albipictus collected in the United States by 17kDa-based PCR. As tick populations continue to increase and expand in North America, correct identification of ticks collected from pets is critical to accurately track the progression and spread of ticks and tick-borne diseases.

Within-population diversity of bacterial microbiomes in winter ticks (Dermacentor albipictus)

The bacterial microbiome of ticks is notoriously diverse, but the factors leading to this diversity are poorly understood. We sequenced bacterial 16S rRNA amplicons from individual winter ticks, Dermacentor albipictus, to assess whether their one-host life cycle is associated with reduced bacterial diversity. On average, about 100 bacterial genera were found for individual ticks. Francisella-like endosymbiont (FLE) dominated bacterial communities, particularly in female ticks and in ticks that had fed. The remainder of the winter tick microbiome was highly variable. In addition to FLE, the main bacterial genera associated with winter ticks on elk were Pseudomonas, Ehrlichia, Asinibacterium, Acinetobacter and Streptococcus, although sequences associated with hundreds of other minor bacterial genera were detected. A complex interaction between richness and evenness was revealed in comparisons among tick life stages, using the Hill number series to show trends in diversity with decreasing emphasis on rare members of the assemblage. Male ticks had a significantly greater number of bacterial genera than females or nymphs, while males had greater evenness than females and similar evenness to nymphs. We intentionally sampled ticks from a single host species, North American elk, from a single location in Alberta, Canada, to constrain the ecological and blood meal variation that individuals experience through their life cycle. In spite of this, we found that the number of bacterial genera detected in this one-host tick system was remarkably diverse. The high taxonomic variability of the minor components of the winter tick microbiome suggests that this part of their microbiome diversity should be examined for functional significance.

Metabolic and Population Effects of Winter Tick Infestations on Moose: Unique Evolutionary Circumstances?

Moose (Alces alces) have evolved to store adequate body fat to emerge from winter in adequate nutritional condition that is key to annual productivity and neonatal survival. Blood consumption by winter ticks (Dermacentor albipictus) affects survival and productivity of moose, often resulting in marked local and regional die-offs of the calf segment of the population. Concurrent with an unprecedented frequency of winter tick epizootics (> 50% calf mortality) in the northeastern United States, productivity but not mortality of adult female moose has also declined due to low rates of twinning and calving. Chronic blood loss to winter ticks affects protein and energy balance in late winter-early spring when pregnant cows are in their energy- and protein-costly 3rd trimester, and will eventually calve and lactate initially in an environment low in digestible energy and protein. To describe this dynamic, I calculated the endogenous fat and protein balance of different-sized pregnant cows by developing energy balance equations that accounted temporally for gestation, winter tick infestation, and lactation under two consumption levels. The analysis revealed the critical importance of body mass and body fat as only large cows (25% pre-winter body fat) were immune from depletion of body fat at birth in all scenarios. Mid-sized cows (20% body fat) depleted fat reserves during gestation in most scenarios, and small cows (15% body fat) in all scenarios. The infestation and forage consumption levels influenced the predicted date of fat depletion up to several weeks, and failed calving or mortal mass loss associated with rapid loss of endogenous protein was possible in mid-sized and small cows. The continual decline in demographic parameters points to reduced body mass and body fat over time, or increased numbers of mid-sized and small cows in the population. Recent research is suggestive of a self-sustaining relationship largely influenced, ironically, by quality habitat and patterns of habitat use. This regional population is confronted with a unique and sustained combination of environmental and parasitic conditions associated with a warming climate that markedly affects its survival and reproduction in quality habitat, a unique occurrence in their evolutionary history.

Evaluating moose Alces alces population response to infestation level of winter ticks Dermacentor albipictus

Many wildlife populations are experiencing a variety of environmental pressures due to the direct and indirect consequences of a changing climate. In the northeast, USA, moose Alces alces are declining in large part because of the increasing parasitism by winter tick Dermacentor albipictus, facilitated by high host density and optimal environmental conditions. To test this hypothesis, and better understand the influence of this interaction on the stability of the regional population, we constructed a population viability model using data collected through comprehensive survival and productivity studies in 2002–2005 and 2014–2018 in northern New Hampshire. Years of heavy tick infestation (epizootics) saw a marked reduction in calf survival (< 50%), adult calving (< 60%), twinning rate (< 5%) and complete loss of yearling productivity. We conducted population viability analysis using VORTEX ver. 10.2 to model this moose population for 40 years using mean demographics from both time periods, including environmental variation measured in the field during winter tick epizootic (2002, 2014, 2015, 2016) and non-epizootic (2003, 2004, 2005, 2017) years. This exercise highlights the influence of winter tick infestation on the trajectory of the population with the potential for rapid population growth or decline depending on the frequency of epizootics. We suggest a shift in moose management strategy focused on lowering moose density, assuming continued influence of climate change on the host–parasite relationship.

A RETROSPECTIVE SUMMARY OF CERVID MORBIDITY AND MORTALITY IN ONTARIO AND NUNAVUT REGIONS OF CANADA (1991-2017).

Free-ranging cervids in Canada face diverse threats such as climate change, human population expansion, and the northward spread of vector-borne pathogens. However, we currently have a limited understanding of the impacts of these health challenges in Ontario cervids. Our objective was to identify and characterize causes of morbidity and mortality in free-ranging cervids submitted to the Ontario and Nunavut node of the Canadian Wildlife Health Cooperative (CWHC) over a 27-yr period (1991 to 2017). Submissions included carcasses submitted for full postmortem examination (gross and histopathology; n=196) and field-collected tissues (n=384). Ancillary tests were performed on a case-by-case basis. Univariable logistic regression was used to test for associations between select causes of morbidity and mortality, and factors such as sex, age, and season. Four cervid species were examined: white-tailed deer (Odocoileus virginianus; n=211), moose (Alces alces; n=140), elk (Cervus canadensis; n=136), and caribou (Rangifer tarandus caribou; n=93). Noninfectious disease was the most common general cause of morbidity and mortality (38.1%; 221/580) and was most commonly attributed to trauma (49.7%; 110/221). Deaths attributed to infectious diseases (34.3%; 199/580) were most often bacterial in etiology (45.7%; 91/199). The most common primary infectious disease diagnosed in caribou was digital limb infection, and moose were most commonly diagnosed with parasitic causes, including meningeal worm (Parelaphostrongylus tenuis) and winter tick (Dermacentor albipictus). Chronic wasting disease was not diagnosed among cervids tested during the study period, consistent with the previous lack of detection of the disease in Ontario. These results reveal that anthropogenic, infectious, and environmentally associated causes of morbidity and mortality are commonly diagnosed in cervids submitted to the CWHC Ontario and Nunavut regions, and represent potential population threats that should continue to be monitored.

The effect of climate on population growth in a cold‐adapted ungulate at its equatorial range limit

AbstractClimatic changes are affecting the distribution and viability of species worldwide, and the effects may be greatest for heat‐sensitive organisms in populations situated near the species’ equatorial range limit. We studied the population dynamics of a cold‐adapted large herbivore, moose (Alces alces shirasi), in a population located at the extreme southern range limit of the species in Utah, USA, using a long‐term dataset of aerial counts conducted between 1958 and 2013. We used a modeling approach that acknowledges the uncertainty in the number of moose counted. To determine how climate influenced this population, we tested four models corresponding to different hypotheses suggested by previous studies of moose population dynamics: (1) High summer rainfall increases population growth, (2) severe winters reduce population growth, (3) high summer and winter temperatures cause heat stress which reduces population growth, and (4) snow conditions favorable to winter ticks reduce population growth. We then ranked these models against two additional hypotheses that tested the combined effects of the best‐performing models. The best‐supported model included summer rainfall and the number of days with snow cover in late winter, which described the conditions influencing winter tick numbers, a common parasite of moose in the region. Reproductive female ticks drop off their hosts at the end of winter to lay eggs, and fewer ticks survive in years with abundant snow cover. Positive effects of snow and rainfall indicated that moose population growth was higher following summers with more rainfall and late winters with more days of snow cover, the latter because those conditions likely reduced winter tick numbers. In accordance with global patterns in which altered precipitation regimes are influencing the dynamics of many species, the top‐performing model suggested that both summer and winter precipitation acted together to explain the most variation in moose population growth. Our analysis demonstrates the multiple pathways by which climate and population density can affect the dynamics of temperate species living at their equatorial range limits, including potential parasite‐mediated effects.

Using agent-based models to inform the dynamics of winter tick parasitism of moose

North American moose (Alces alces) populations along the southern extent of their range have been experiencing high levels of calf mortality in recent years. In New England, this phenomenon has been linked to extensive blood loss resulting from extreme winter tick (Dermacentor albipictus) parasitism. Moose are symbolic of the region and generate income through tourism and the auction of hunting permits; thus, successive years of greater than 50% calf mortality (epizootics) are of concern to wildlife managers and others. It is hypothesized that high localized moose density coupled with climate change are the driving forces behind moose-winter tick epizootics; however, the impact that variable combinations of these and other factors have on the occurrence and magnitude of epizootics has not been previously simulated. We, therefore, developed and implemented a spatially explicit agent-based model with two model environments, each representative of a distinct location within an ongoing field study site in northern New Hampshire that differed in the proportional availability of optimal moose habitat. Three experiments were devised to test the sensitivity of the outcome variables, calf infestation level and calf mortality, to 1) winter tick abundance, 2) winter tick aggregation, and 3) moose density, for the length of the winter tick questing period. Each experiment was conducted in both model environments. This model generated similar mortality levels to those measured in the field study under representative moose density and weather conditions. Additionally, the modeled moose agents and the radio-collared moose in the field reflect comparable habitat usage. While the infestation levels reported by calf agents are considered conservative, we believe that future versions of this model, parameterized with more accurate estimates of winter tick abundance and moose density, may be an effective tool for managing moose against winter tick parasitism.

Pathogenicity of Metarhizium anisopliae and Metarhizium brunneum Isolates and Efficacy of Met52 G Against Winter Tick Larvae, 2019

Pathogenicity of Metarhizium anisopliae and Metarhizium brunneum Isolates and Efficacy of Met52 G Against Winter Tick Larvae, 2019

Detection and Transstadial Passage of Babesia Species and Borrelia burgdorferi Sensu Lato in Ticks Collected from Avian and Mammalian Hosts in Canada.

Lyme disease and human babesiosis are the most common tick-borne zoonoses in the Temperate Zone of North America. The number of infected patients has continued to rise globally, and these zoonoses pose a major healthcare threat. This tick-host-pathogen study was conducted to test for infectious microbes associated with Lyme disease and human babesiosis in Canada. Using the flagellin (flaB) gene, three members of the Borrelia burgdorferi sensu lato (Bbsl) complex were detected, namely a Borrelia lanei-like spirochete, Borrelia burgdorferi sensu stricto (Bbss), and a distinct strain that may represent a separate Bbsl genospecies. This novel Bbsl strain was detected in a mouse tick, Ixodes muris, collected from a House Wren, Troglodytes aedon, in Quebec during the southward fall migration. The presence of Bbsl in bird-feeding larvae of I. muris suggests reservoir competency in three passerines (i.e., Common Yellowthroat, House Wren, Magnolia Warbler). Based on the 18S ribosomal RNA (rRNA) gene, three Babesia species (i.e., Babesia divergens-like, Babesia microti, Babesia odocoilei) were detected in field-collected ticks. Not only was B. odocoilei found in songbird-derived ticks, this piroplasm was apparent in adult questing blacklegged ticks, Ixodes scapularis, in southern Canada. By allowing live, engorged ticks to molt, we confirm the transstadial passage of Bbsl in I. muris and B. odocoilei in I. scapularis. Bbss and Babesia microti were detected concurrently in a groundhog tick, Ixodes cookei, in Western Ontario. In Alberta, a winter tick, Dermacentor albipictus, which was collected from a moose, Alces alces, tested positive for Bbss. Notably, a B. divergens-like piroplasm was detected in a rabbit tick, Haemaphysalis leporispalustris, collected from an eastern cottontail in southern Manitoba; this Babesia species is a first-time discovery in Canada. This rabbit tick was also co-infected with Borrelia lanei-like spirochetes, which constitutes a first in Canada. Overall, five ticks were concurrently infected with Babesia and Bbsl pathogens and, after the molt, could potentially co-infect humans. Notably, we provide the first authentic report of I. scapularis ticks co-infected with Bbsl and B. odocoilei in Canada. The full extent of infectious microorganisms transmitted to humans by ticks is not fully elucidated, and clinicians need to be aware of the complexity of these tick-transmitted enzootic agents on human health. Diagnosis and treatment must be administered by those with accredited medical training in tick-borne zoonosis.

Comparative Microbiome Profiles of Sympatric Tick Species from the Far-Western United States.

Insight into the composition and function of the tick microbiome has expanded considerably in recent years. Thus far, tick microbiome studies have focused on species and life stages that are responsible for transmitting disease. In this study we conducted extensive field sampling of six tick species in the far-western United States to comparatively examine the microbial composition of sympatric tick species: Ixodes pacificus, Ixodes angustus, Dermacentor variabilis, Dermacentor occidentalis, Dermacentor albipictus, and Haemaphysalis leporispalustris. These species represent both common vectors of disease and species that rarely encounter humans, exhibiting a range of host preferences and natural history. We found significant differences in microbial species diversity and composition by tick species and life stage. The microbiome of most species examined were dominated by a few primary endosymbionts. Across all species, the relative abundance of these endosymbionts increased with life stage while species richness and diversity decreased with development. Only one species, I. angustus, did not show the presence of a single dominant microbial species indicating the unique physiology of this species or its interaction with the surrounding environment. Tick species that specialize in a small number of host species or habitat ranges exhibited lower microbiome diversity, suggesting that exposure to environmental conditions or host blood meal diversity can affect the tick microbiome which in turn may affect pathogen transmission. These findings reveal important associations between ticks and their microbial community and improve our understanding of the function of non-pathogenic microbiomes in tick physiology and pathogen transmission.

Passive Animal Surveillance to Identify Ticks in Wisconsin, 2011-2017.

The introduction of new tick species poses a risk to human and animal health. Systematic active surveillance programs are expensive and uncommon. We evaluated a passive animal surveillance program as a monitoring tool to document the geographic distribution and host associations of ticks in Wisconsin. Passive surveillance partners included veterinary medical clinics, domestic animal shelters, and wildlife rehabilitation centers from 35 of the 72 Wisconsin counties. A total of 10,136 tick specimens were collected from 2325 animals from July 2011 to November 2017 and included Dermacentor variabilis Say (29.7% of all ticks), Ixodes texanus Banks (25.5%), Ixodes scapularis Say (19.5%), Haemaphysalis leporispalustris Packard (13.8%), Ixodes cookei Packard (4.4%), and Dermacentor albipictus Packard (1.7%). Less common species (<1% of collection) included Ixodes dentatus Marx, Ixodes sculptus Neumann, Ixodes marxi Banks, Amblyomma americanum Linnaeus, and Rhipicephalus sanguineus Latreille. Of the 2325 animals that were examined, most were domestic dogs (53%), eastern cottontail rabbits (16%), domestic cats (15%), and North American raccoons (11%). An additional 21 mammal and 11 bird species were examined at least once during the six years of the study. New county records are summarized for each species. Public health, academic, and veterinary and animal care partners formed a community of practice enabling effective statewide tick surveillance.

Winter Tick (Dermacentor albipictus)–Associated Dermatitis in a Wild Elk (Cervus canadensis) in Pennsylvania, USA

In 2017, a male elk (Cervus canadensis) was found dead in Pennsylvania, US. The elk was in poor nutritional condition and had alopecia and ulcerative dermatitis throughout the neck and dorsum region associated with severe Dermacentor albipictus infestations. Histologically, there was severe chronic-active dermatitis with hyperkeratosis and crust formation.

125 Tick burden observed on cattle and sheep during winter season on the Edwards Plateau of Texas

Abstract Multi-species livestock grazing is a common practice in the Edwards Plateau of Texas. Winter demands on livestock are high because of forage quality and quantity limitations and stresses of tick parasitism. Our objective was to assess winter-active tick burden on livestock and gauge effectiveness of a pour-on synthetic pyrethroid acaricide. At the Sonora AgriLife Station, 26 Bos taurus crossbred heifers (260 ± 6 kg) and 28 Dorper ewes (42 ± 1 kg) were maintained on 97.125 hectares of rangeland. Tick burden was assessed by individual animal inspection on: 12-18-2017, 01-05-2018, 01-122018, 01-26-2018, 02-09-2018, 02-16-2018, 02-23-2018, and 03-08-2018. Trial 1 acaricide treatment was applied 01-05-2018 on heifers and ewes chosen randomly to serve in the non-treated control (13 heifers; 14 ewes) or acaricide-treated (13 heifers; 14 ewes) groups. Trial 2 acaricide treatment was applied 02-16-2018 using a switchback design. Tick species included Amblyomma americanum, Dermacentor albipictus, and Ixodes scapularis. Tick burden differences were determined by analysis of variance procedures. There were no differences in tick burden on heifers or ewes prior to acaricide application for Trial 1 nor Trial 2 (P &gt; 0.276, 0.002 ± 0.46; P &gt; 0.354, 0.002 ± 0.11 and P &gt; 0.606, 0.002 ± 0.05; P &gt; 0.705, 0.001 ± 1.34, respectively). There were no differences (P &gt; 0.149) between acaricide-treated (0.519 ± 0.05) and non-treated control (0.644 ± 0.07) heifers in Trial 1 nor Trial 2 (0.759 ± 0.07 and 0.404 ± 0.04, respectively). Similarly, there were no differences (P &gt; 0.997) between acaricide-treated (2.964 ± 0.31) and non-treated control (2.965 ± 0.3) ewes in Trial 1 nor Trial 2 (1.015 ± 0.13 and 5.563 ± 0.45, respectively). We conclude ticks challenge the well-being and production in overwintering livestock in the Edwards Plateau. Alternative acaricides should be evaluated for efficacy and efficiency in these production systems

Comparison of some Molecular Markers for Tick Species Identification

Ticks are obligate blood-sucking ectoparasites of vertebrates. Since many tick identification studies are based on the analysis of 16S rDNA, 12S rDNA and ITS-1, 2 rDNA genes, we aimed to compare the performance of these molecular markers of common use for the identification of ticks, under a diagnostic laboratory environment. Overall, 192 tick specimens were collected through the state of Texas from January 2014 to August 2015 and the species was determined by both morphology and molecular amplification using the 16S rDNA, 12S rDNA, ITS1 and ITS2. The species collected were identified by molecular techniques as Dermacentor albipictus, D. variabilis, Amblyomma americanum, Ixodes scapularis, A. cajennense, Rhipicephalus sanguineus and Carios capensis. ITS1 and ITS2 were not able to prove consistent amplification and therefore have been considered as potential markers for tick identification. The use of mitochondrial genes in tick identification showed to provide more consistent results in the diagnostic environment.

Vertical transmission of the entomopathogenic soil fungus Scopulariopsis brevicaulis as a contaminant of eggs in the winter tick, Dermacentor albipictus, collected from calf moose (New Hampshire, USA)

ABSTRACT Moose naturally acquire soil fungi on their fur that are entomopathogenic to the winter tick, Dermacentor albipictus. Presumed to provide a measure of on-host tick control, it is unknown whether these soil fungi impact subsequent off-host stages of the tick. Eggs and resultant larvae originating from engorged, adult female winter ticks collected from dead calf moose (Alces alces) were used to investigate the presence and extent of fungal infection. Approximately 40% of eggs and larvae were infected, almost exclusively by the fungus Scopulariopsis brevicaulis (teleomorph Microascus brevicaulis: Microascaceae, Ascomycota). Eggs analysed on the day of oviposition and day of hatching had high frequency (40%) of S. brevicaulis, whereas the frequency in eggs harvested in utero was minimal (7%); therefore, exposure occurs pre-oviposition in the female’s genital chamber, not by transovarial transmission. At hatching, larvae emerge containing S. brevicaulis indicating transstadial transmission. Artificial infection by topical application of eggs and larvae with a large inoculum of S. brevicaulis spores caused rapid dehydration, marked mortality; pathogenicity was confirmed by Koch’s postulates. The high hatching success (>90%) and multi-month survival of larvae imply that S. brevicaulis is maintained as a natural pathobiont in winter ticks.

Tick development on sexually-active bull moose is more advanced compared to that of cow moose in the winter tick, Dermacentor albipictus.

We performed a complete survey of ticks on 100 cm2 skin samples collected from 30 moose (Alces alces) harvested in 2017 in central and northern Maine, U.S.A. The samples were collected from 15 bulls, 13 cows, and 2 calves in mid-October when moose are breeding and winter ticks (Dermacentor albipictus) quest for a host. We identified only winter ticks with 99.2% in a juvenile stage; 3 adult ticks were found. Unfed nymphs were most common on bulls, whereas most ticks were fed larvae on cows and calves. The mean total count on bull samples was 21 ± 4.4 (range = 0–55) and higher than on cows (6 ± 0.5; range = 2–8). Unlike previous surveys, tick abundance was lowest on calves. Tick abundance was independent of age or weight of adult moose. The higher abundance and more rapid development of winter ticks on adult bulls likely reflects the seasonal influence of increased movements and hormonal cycles associated with reproduction.

Enhancement of fur and skin from bull moose with additional entomopathogenic fungi that offer increased protection against damage from winter ticks (Dermacentor albipictus; Acari: Ixodidae)

ABSTRACTCertain moose (Alces alces) populations in the northeastern United States are in decline because of increasing frequency of winter tick (Dermacentor albipictus) epizootics characterized by high calf mortality and reduced productivity in the population. Previous research identified soil fungi in wallows of bull moose that are pathogenic to larval winter ticks. We analysed skin/hair samples of moose harvested in Maine, USA, to further understand this fungus–tick–moose relationship. A total of 32 keratinophilic fungi from moose fur and skins were isolated, predominately Penicillium, Cladosporium, Aspergillus, Alternaria, Trichoderma, Beauveria, and Scopulariopsis. Each displayed pathogenic activity against unfed winter tick larvae (sole infestation stage) by topical application of spore inoculums and Koch’s postulates. Bulls had more entomopathogenic fungi, pathogenic fungal isolates to ticks, and infected larvae than cows and calves. We propose a disease cycle with interactions of soil fungi, moose, and on-host winter tick larvae killed by entomopathogenic soil fungi. Bull moose presumably experience enhanced exposure and protection from abundant soil fungi due to their wallowing behaviour during the breeding season that is coincidental with questing by winter tick larvae.

HEALTH SURVEY OF BOREAL CARIBOU (RANGIFER TARANDUS CARIBOU) IN NORTHEASTERN BRITISH COLUMBIA, CANADA.

Boreal woodland caribou (Rangifer tarandus caribou) are listed as threatened across Canada, and a basic understanding of their health status is lacking. From December 2012 to April 2013, we investigated multiple health indices for adult female boreal caribou (n=163) captured from seven herds in NE British Columbia, Canada. Health indices included physical characteristics, physiologic and trace mineral status, exposure to or infection with selected pathogens, and measures of chronic stress and inflammation, including serum amyloid A, haptoglobin, and hair cortisol concentration. Key findings were exposure to the bacterium Erysipelothrix rhusiopathiae in 14% of individuals, mild to severe hair loss associated with winter tick (Dermacentor albipictus) infestations in 76% of caribou from December to early February and 81% from late February to early April, and evidence of trace mineral deficiencies with 99% and 34% of individuals deficient in copper and selenium, respectively. Seroprevalence for exposure to selected pathogens was: alphaherpesvirus (63%), pestivirus (1%), Besnoitia spp. (60%), and Neospora caninum (2%). All animals were seronegative to Brucella spp. and Toxoplasma gondii. Mycobacterium avium ssp. paratuberculosis was not detected in any fecal samples. Parasite eggs or larvae, including Parelaphostrongylus andersoni (36%), Skrjabinema spp. (1%), Strongyle-type eggs (11%), Moniezia-type eggs (8%), and nematodirines (3%), were detected on fecal examination, but at low intensity. Blood biochemistry values and hair cortisol concentrations were within ranges previously reported in Rangifer tarandus sspp. Some significant differences among herds were noted, including antler morphology, exposure to Besnoitia spp., and concentrations of serum amyloid A, copper, cobalt, manganese, and iron.