Article

The distribution of Dermacentor ticks in Canada in relation to bioclimatic zones

Canadian Journal of Zoology (Impact Factor: 1.3). 08/1967; 45(4):517-37. DOI: 10.1139/z67-066
Source: PubMed

ABSTRACT

Dermacentor andersoni has been collected north of Jasper, Alberta, close to 54° N. and near 53° N. in British Columbia. Spread to the north and northwest is probably limited by low summer soil temperatures, which would act principally by slowing egg development, thus disrupting the seasonal cycle of the tick. To the southwest, mild winters may fail to release diapause at the correct time of year. Aspect and slope are important factors. Altitude spread of records is from 1000–7000 ft. The most generally applicable description of its distribution is the ecotone between western grassland and moister regions, including clearings and rocky outcrops m the montane and Columbia forests, and shrubby areas of the prairies. In British Columbia, a series of randomly selected transects indicated a strong association between the tick's presence and several species of shrubs growing without tree shade.Each bioclimatic zone tends to have a characteristic group of rodents as main hosts of the immature stages. The prairie and montane regions differ in the indigenous hosts available to the adult tick.East of 105° D. andersoni is replaced by D. variabilis, which is adapted to the more humid summers of the eastern deciduous forest zones, and differs considerably from D. andersoni in its phenology. There are no reliable records of indigenous D. variabilis north of 52° latitude.D. albipictus occurs from the east to the west coast. Because of the winter activity of its larvae, allowing the whole summer for egg development, it is able to penetrate much farther north than the other two species. There are two records close to 60° latitude.

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    • "to the egg. Temperature influences the rate of embryo development in poikilothermic animals and, therefore, determines the time of larval hatch in Dermacentor species (Wilkinson 1967, Darvishi et al. 2014, Magdas et al. 2015). Tick embryogenesis is also sensitive to relative humidity, which varies depending on the tick species (D'Alessandro et al. 2014). "

    No preview · Article · Dec 2015 · Journal of Medical Entomology
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    • "Winter ticks are a common pest of horses, elk, mule deer, moose, and other wildlife species in the United States, in addition to occasionally infesting cattle (Wilkinson 1967, Samuel et al. 1991). These Dermacentor species extend much further north than other Dermacentor species and are able to use a much broader seasonal window for development than other species (Wilkinson 1967). Although no information has quantified the ability of D. albipictus populations to persist at higher elevations, this species is present at higher latitudes and commonly found on a variety of wildlife that are adapted to higher elevations. "
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    ABSTRACT: Livestock parasitism on high-elevation rangeland (>1,800 m (6,000’)) may not be as well documented as parasitism is at lower elevations because producers assume elevation limits parasite persistence and exposure of livestock to parasites. Certain parasites, such as horn flies, Haematobia irritans (L.) (Diptera: Muscidae), and biting midges, Culicoides spp. (Diptera: Ceratopogonidae), a vector of bluetongue virus, are restricted to lower elevations. However, some parasites are endemic to high elevations, such as the Rocky Mountain wood tick, Dermacentor andersoni (Stiles) (Acari: Ixodidae), a vector of many diseases. Multiple horse fly and mosquito species persist at various elevation gradients, with some having preference for lower or higher elevations. For example, the horse fly, Hybomitra laticornis (Hine) (Diptera: Tabanidae), occurred from 1,700-3,035 m (5,577’-9,957’), Hybomitra phaenops (Osten Sacken) (Diptera: Tabanidae) only occurred above 2,499 m (8,198’), and the western horse fly, Tabanus punctifer (Osten Sacken) (Diptera: Tabanidae), only occurred below 2,250 m (7,381’). This variable elevation range is also expressed by several mosquito species, with six of 12 known mosquito species that transmit West Nile virus at or above 1,750 m (5,740’). Furthermore, gastrointestinal roundworms can survive > 1 yr at high elevations, use larvae inhibition to survive winter, and lungworm infection may increase with elevation. Evidence suggests changing weather patterns, climate variability, and animal movements could shift some parasites and diseases into higher elevations, such as mosquitoes and biting midges. Moving livestock to high-elevation ranges may also increase the opportunity for livestock-wildlife interactions, parasite and disease transmission, and exposure. Producers should develop high-elevation integrated pest management strategies, such as delaying or avoiding parasite treatment to optimize efficacy and reduce input costs, monitoring closely during wet years and periods of livestock-wildlife interactions, using elevation to avoid certain parasites, and not assuming that elevation is capable of preventing livestock parasitism.
    Full-text · Article · Mar 2015
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    • "At least 18.5% of adult ticks collected during the vector season of 1 yr overwintered to the next vector season . This is significant because in much of the historical literature, American dog ticks were not expected to survive two vector seasons in Manitoba (Wilkinson 1967, McEnroe 1975, Sonenshine 1979, Burachynsky and Galloway 1985, Sonenshine 1993). Although, in similar studies, unfed adult Dermacentor spp. "
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    ABSTRACT: One thousand seven hundred unfed field-collected adult Dermacentor variabilis (Say) were overwintered in 34 outdoor enclosures near the northern limit of their distribution in Manitoba, Canada. At the northern limits of the range of D. variabilis, it had always been assumed that unfed adult ticks questing in spring succumbed before the next winter and were not part of the population observed in the following year. Survival of the collected ticks was assessed on two occasions. In midwinter, an average 39.4% (SE ± 2.50) of the ticks were still alive, while an average 19.9% (SE ± 1.14) survived to April. Female ticks had significantly higher survivorship than males. The ability to survive an additional winter allows ticks to act in a greater capacity as reservoirs for tick-associated pathogens in this region. © The Authors 2015. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email: journals.permissions@oup.com.
    Full-text · Article · Mar 2015 · Journal of Medical Entomology
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