Distribution of the American dog tick, Dermacentor variabilis (Say), and its small-mammal hosts in relation to vegetation types in a study area in Nova Scotia

The distribution of Dermacentor variabilis and its mammal hosts was related to vegetation types found in a 12-ha area of southwestern Nova Scotia during summers of 1974 to 1977. Cluster and principal component analyses were used to elucidate these relationships. Habitats, live-trapped for small mammals, were categorized into seven major vegetation types: old field, ecotone – old field, ecotone–powerline, shrubs–trees, mixed woods low–wet, mixed woods open canopy, and mixed woods closed canopy. Clethrionomys gapperi, Peromyscus spp. (mainly P. leucopus, about 10% P. maniculatus) and Tamias striatus were most frequently trapped in the mixed deciduous and coniferous wood areas, although the latter two genera were also captured in the old field and ecotone – old field areas. Microtus pennsylvanicus, Zapus hudsonius, and adult and nymph stages of Dermacentor variabilis occurred most frequently in the old field and ecotone areas. Tick nymphs fed almost exclusively on Microtus pennsylvanicus, but also utilized Peromyscus spp. in the ecotone and woodland areas. In contrast to the nymphs, over half the tick larvae were collected from Clethrionomys gapperi and Peromyscus spp. captured in the ecotone–powerline, shrubs–trees, and mixed wood areas, whereas less than half the tick larvae were collected from mammals inhabiting the old field and ecotone – old field areas. Peromyscus spp. probably helped disperse engorged tick larvae from the woodland to the old field and ecotone areas.

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Seasonal dynamics and distribution of American dog tick, Dermacentor variabilis (Say), larvae and nymphs at Birds Hill Park, Manitoba

Canadian Journal of Zoology ◽

10.1139/z85-410 ◽

1985 ◽

Vol 63 (12) ◽

pp. 2748-2755 ◽

Cited By ~ 7

Author(s):

V. I. Burachynsky ◽

T. D. Galloway

Keyword(s):

Dermacentor Variabilis ◽

Microtus Pennsylvanicus ◽

Tamiasciurus Hudsonicus ◽

Clethrionomys Gapperi ◽

Spermophilus Tridecemlineatus ◽

Mammal Species ◽

Tamias Striatus ◽

Sorex Cinereus ◽

Spermophilus Franklinii ◽

Dog Tick

During a 2-year study on the relationships between immature Dermacentor variabilis and their small-mammal hosts near Birds Hill, Manitoba, 739 captures of 427 mammals were examined for ticks. Captures represented 11 mammal species: Clethrionomys gapperi, Lepus americanus, Microtus pennsylvanicus, Mus musculus, Peromyscus maniculatus, Sorex cinereus, Spermophilus franklinii, Spermophilus tridecemlineatus, Tamias striatus, Tamiasciurus hudsonicus, and Zapus hudsonius. Clethrionomys gapperi, M. pennsylvanicus, P. maniculatus, S. franklinii, and Z. hudsonius were most frequently encountered and, with the exception of S. franklinii, infested with larvae and nymphs. Clethrionomys gapperi were most frequently infested by D. variabilis and produced 42.6% and 60.5% of larvae collected in 1979 and 1980, respectively, and over 85% of all nymphs. Peak larval infestation occurred between the last week of May and the middle of June; that for nymphs occurred in July in both 1979 and 1980. Dermacentor variabilis appeared to have a 2-year life cycle in Manitoba. Larvae were spatially aggregated during both years and aggregates were located in different areas of the plots each year. Nymphs were less aggregated than larvae. The distribution of nymphs overlapped that of larvae each year and occupied a greater area on the plots.

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Ecology of the American dog tick, Dermacentor variabilis (Say), in Nova Scotia

Canadian Journal of Zoology ◽

10.1139/z69-039 ◽

1969 ◽

Vol 47 (2) ◽

pp. 171-181 ◽

Cited By ~ 12

Author(s):

Donald G. Dodds ◽

Arthur M. Martell ◽

Richard E. Yescott

Keyword(s):

Nova Scotia ◽

Deer Mouse ◽

Black Bear ◽

Dermacentor Variabilis ◽

Meadow Vole ◽

Mammal Species ◽

Erethizon Dorsatum ◽

American Dog Tick ◽

Dog Tick ◽

Small Mammal Species

The American dog tick has been extending its range in western Nova Scotia since about 1940. The presence of a number of suitable hosts, a temperate, moist climate, and logging operations producing an interspersion of choice vegetative conditions allow relatively high densities and a continuous spread. Seven small mammal species act as hosts. The most important hosts of immature stages are meadow vole (Microtus pennsylvanicus), deer mouse (Peromyscus maniculatus), southern bog lemming (Synaptomys cooperi), and meadow jumping mouse (Zapus hudsonius). Important hosts for adult stages are porcupine (Erethizon dorsatum), raccoon (Procyon lotor), and black bear (Ursus americanus).

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Seasonal dynamics of American dog tick, Dermacentor variabilis (Say), populations in southwestern Nova Scotia

Canadian Journal of Zoology ◽

10.1139/z78-004 ◽

1978 ◽

Vol 56 (1) ◽

pp. 28-39 ◽

Cited By ~ 27

Author(s):

Maxwell B. Garvie ◽

John A. Mckiel ◽

Daniel E. Sonenshine ◽

Alan Campbell

Keyword(s):

Nova Scotia ◽

Larval Density ◽

Weather Conditions ◽

Adult Tick ◽

Dermacentor Variabilis ◽

Life Cycles ◽

Main Peak ◽

American Dog Tick ◽

Population Peak ◽

Dog Tick

Seasonal activity and host relationships of the American dog tick in three areas of southwestern Nova Scotia are described from 1973 to 1975. The majority of Dermacentor variabilis individuals undergo a 2-year life cycle in Nova Scotia. Unfed adults and larvae are the two main overwintering stages. Adult tick activity extends from April to mid-August, with one population peak during May and (or) June. Peak adult densities, based on mark–recapture methods, were estimated between 7887 and 20 909 ticks per hectare at two areas during 1974 and 1975. Larval activity extending from late April to September was usually bimodal. The main peak of overwintered larvae engorged during June, while a second peak of recently hatched larvae, depending on weather conditions, usually occurred during August. The main relative larval density during the dominant spring peak was 3.95 larvae per host. Nymphal populations occurred between May and August with the unimodal activity pattern averaging 3.85 nymphs per host at the peak during June. The voles Microtus pennsylvanicus and Clethrionomys gapperi sustained almost 80% of all larvae and over 85% of all nymphs collected from mammal hosts. The snowshoe hare, Lepus americanus, and the jumping mouse, Zapus hudsonius, also harbored substantial numbers of immature ticks. Dermacentor variabilis life cycles studied in Massachusetts, Virginia, and Nova Scotia are compared.

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Occurrence of the American Dog Tick, Dermacentor variabilis (Say) in Western Nova Scotia

The Canadian Entomologist ◽

10.4039/ent93891-10 ◽

1961 ◽

Vol 93 (10) ◽

pp. 891-893 ◽

Cited By ~ 5

Author(s):

R. R. Hall ◽

J. A. McKiel

Keyword(s):

United States ◽

Nova Scotia ◽

Dermacentor Variabilis ◽

Coastal Plains ◽

Eastern United States ◽

Male And Female ◽

American Dog Tick ◽

Far North ◽

Dog Tick

The American dog tick, Dermacentor variabilis (Say) is abundant in many localities throughout the coastal plains of eastern United States (Bequaert, 1946) and according to Lewis (1960) occurs in sparse numbers as far north as the Bangor area in Maine. In Canada, it is found from Saskatchewan to Nova Scotia (Gregson, 1956) but seemingly only in small numbers and in widely separated areas east of Manitoba. The published information on its occurrence in Nova Scotia is limited to a single record by Twinn (1944) who mentioned that male and female American dog ticks in “considerable numbers” were taken at the upper waters of the Sissiboo River in Digby County. Since its presence in western Nova Scotia in infestation numbers does not appear to be generally known outside that province, it is felt that a note on our observations on D. variabilis might be of interest.

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ECOLOGY OF THE AMERICAN DOG TICK, DERMACENTOR VARIABILIS IN SOUTHWESTERN NOVA SCOTIA

Recent Advances in Acarology ◽

10.1016/b978-0-12-592202-9.50022-7 ◽

1979 ◽

pp. 135-143 ◽

Cited By ~ 2

Author(s):

Alan Campbell

Keyword(s):

Nova Scotia ◽

Dermacentor Variabilis ◽

American Dog Tick ◽

Dog Tick

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Supercooling Points of Adult Dermacentor variabilis (Acari: Ixodidae) From a Population Near the Northern Distribution Limit

Journal of Medical Entomology ◽

10.1093/jme/tjaa223 ◽

2020 ◽

Author(s):

Matthew E M Yunik ◽

Neil B Chilton

Keyword(s):

Cold Hardiness ◽

Dermacentor Variabilis ◽

Subzero Temperatures ◽

Host Seeking ◽

Short Period ◽

Significant Difference ◽

Northern Distribution ◽

Dog Tick ◽

Provincial Park ◽

Established Population

Abstract The northern distributional limit of Dermacentor variabilis Say, the American dog tick, is expanding in Saskatchewan and Manitoba (western Canada). The ability of D. variabilis to continue to expand its range northwards will depend upon the ability of individuals within populations at the species distributional edge to withstand very low temperatures during winter. One component of cold hardiness is the supercooling point (SCP), the temperature below 0°C at which an individual freezes. In this study, the SCP was determined for 94 questing D. variabilis adults (44 females and 50 males) from an established population near Blackstrap Provincial Park in Saskatchewan. SCP values ranged from −18.2 to −6.7°C, with a median of −13.3°C. This suggests that host-seeking D. variabilis adults differ in their ability to survive exposure to subzero temperatures, for at least a short period of time, without freezing. The distribution of SCPs was bimodal, but there was no significant difference in SCP values between female and male ticks, and no relationship between SCP and tick body weight. It remains to be determined what factors contribute to the variation in SCP values among questing D. variabilis adults.

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Tick Ecdysteroid Hormone, Global Microbiota/Rickettsia Signaling in the Ovary versus Carcass during Vitellogenesis in Part-Fed (Virgin) American Dog Ticks, Dermacentor variabilis

Microorganisms ◽

10.3390/microorganisms9061242 ◽

2021 ◽

Vol 9 (6) ◽

pp. 1242

Author(s):

Loganathan Ponnusamy ◽

Haley Sutton ◽

Robert D. Mitchell ◽

Daniel E. Sonenshine ◽

Charles S. Apperson ◽

...

Keyword(s):

Hormonal Regulation ◽

Natural Populations ◽

Blood Feeding ◽

Dermacentor Variabilis ◽

Transovarial Transmission ◽

Rickettsia Species ◽

Adult Females ◽

Dog Tick ◽

Total Bacteria

The transovarial transmission of tick-borne bacterial pathogens is an important mechanism for their maintenance in natural populations and transmission, causing disease in humans and animals. The mechanism for this transmission and the possible role of tick hormones facilitating this process have never been studied. Injections of physiological levels of the tick hormone, 20-hydroxyecdysone (20E), into part-fed (virgin) adult females of the American dog tick, Dermacentor variabilis, attached to the host caused a reduction in density of Rickettsia montanensis in the carcass and an increase in the ovaries compared to buffer-injected controls. This injection initiates yolk protein synthesis and uptake by the eggs but has no effect on blood feeding. Francisella sp. and R. montanensis were the predominant bacteria based on the proportionality in the carcass and ovary. The total bacteria load increased in the carcass and ovaries, and bacteria in the genus Pseudomonas increased in the carcass after the 20E injection. The mechanism of how the Rickettsia species respond to changes in tick hormonal regulation needs further investigation. Multiple possible mechanisms for the proliferation of R. montanensis in the ovaries are proposed.

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