Dermacentor albipictus

Packard, 1869

winter tick, moose tick

Dermacentor albipictus, commonly known as the winter or moose tick, is a one- hard tick native to North America. It is primarily known as a serious pest of moose (Alces alces), with heavy of up to 150,000 ticks documented on individual animals, often leading to death. The tick also parasitizes other cervids including elk, white-tailed deer, mule deer, and caribou, as well as cattle and horses. Unlike many tick , D. albipictus is not known to transmit to humans, wildlife, or domestic animals. Its spans approximately one year, with all feeding stages occurring on a single host.

Dermacentor albipictus by (c) Dustin Snider, some rights reserved (CC BY), uploaded by Dustin Snider. Used under a CC-BY license.

Cattle ticks (Ixodoidea) of the United States (1902) (20398748888) by Salmon, D. E;

Stiles, Charles Wardell, 1867-1941. Used under a No restrictions license.

Dermacentor albipictus larva by Emily S. Chenery. Used under a CC BY 4.0 license.

Pronunciation

How to pronounce Dermacentor albipictus: /dɛrməˈsɛntɔr ælˈbɪpɪktəs/

These audio files are automatically generated. While they are not always 100% accurate, they are a good starting point.

Identification

Distinguishable from other Dermacentor by the white shield on females and white markings on males. The one- is distinctive among Dermacentor ticks—most are three-host ticks. () and Dermacentor andersoni (Rocky Mountain wood tick) have different seasonal activity patterns and host associations. Dermacentor albipictus is active primarily in autumn through winter, whereas D. variabilis peaks in spring and summer. Molecular identification may be complicated by deep mitochondrial lineage divergences within that do not indicate distinct species.

Images

Appearance

are sexually dimorphic. The adult female is mostly reddish-brown with a white shield () behind the ; engorged females become unusually large, measuring up to 15 mm. The smaller adult male is dark brown with white markings. As a hard (Ixodidae), it possesses a prominent scutum. Larvae and nymphs are considerably smaller and difficult to detect visually.

Habitat

Found in areas with presence of large ungulate , particularly moose. Larvae occur on grassy vegetation up to 1.25 m in height, especially on south-facing slopes. Off-host stages utilize leaf litter and ground-level vegetation. The completes its entire in forested and semi-open across northern North America, including areas north of 60° latitude in Yukon, Canada.

Distribution

Widespread across North America from Alaska and Canada through the United States; documented in Yukon, Alberta, Saskatchewan, Pennsylvania, and northeastern states. GBIF records indicate presence in United States, Guatemala, Mexico, and Hawaii. The shows potential for range expansion with changing climate conditions.

Seasonality

Larval questing peaks in late September to early October; larvae attach to in autumn. All feeding stages (larva, nymph, ) occur on the single host through winter. Engorged females drop off hosts in late winter to early spring (late March to early April documented in Ontario) to lay . Adults mate on the host during late winter. Hosts are free of ticks during summer months.

Host Associations

Alces alces (moose) - primary most severely affected ; heavy cause anemia, hair loss, emaciation, and death
Cervus canadensis (elk) - typically low burdens with mild or no ; severe rare
Odocoileus virginianus (white-tailed deer) - better at and removal than moose; lower levels
Odocoileus hemionus (mule deer) -
Rangifer tarandus (caribou) -
Bos taurus (cattle) - incidental can cause serious losses when cattle graze in moose ; preventable by keeping animals in -free pastures September–May
Equus caballus (horses) - incidental similar to cattle, vulnerable when grazing in -infested areas
Sus scrofa (feral swine) - may increase and distribution in some areas

Life Cycle

A one- with approximately one-year . Engorged females drop off hosts in late winter to early spring and lay masses of up to 3,000 eggs in leaf litter. Eggs hatch in late summer or early spring after a pre-oviposition period; laboratory studies indicate 28–32 days incubation at 21°C. Larvae undergo a period of , then ascend vegetation up to 1.25 m and cluster in groups of approximately 1,000 to quest for hosts. Upon host contact, larvae attach and feed, then to nymphs on the same host (approximately 10 days post-attachment documented). Nymphs undergo an extended before molting to in mid-February; this diapause likely delays maturity until warmer weather. Adults feed and mate on the host; males remain on the host for life and die there, while engorged females drop off to oviposit. The diapause mechanism synchronizes development with seasonal conditions.

Behavior

Larvae exhibit questing on vegetation, extending forelegs to detect passing . They respond to host-associated stimuli including odor, heat, movement, and vibration. Larvae cluster on vegetation, which increases encounter rates with hosts. Off-host larvae demonstrate survival capabilities underwater for extended periods (63% survival after 5 weeks for 1-month-old larvae; 23% survival after 7 days for 3-month-old larvae). females show reduced oviposition success after submergence. The extended nymphal represents a key behavioral for seasonal synchronization.

Ecological Role

A significant of large ungulates with documented -level impacts on moose. Heavy cause anemia, hair loss, reduced , and mortality; calf mortality rates of 91% attributed to winter infestation documented in Vermont studies. Reduced moose populations have cascading effects on vegetation —increased abundance of shrubs and balsam fir documented following moose declines on Isle Royale. The tick does not transmit agents, limiting its role as a but not its impact as a parasite. Climate warming correlates with increased tick abundance, with shorter winters associated with higher survival and infestation rates.

Human Relevance

Occasionally bites humans but is not known to transmit . Heavy on livestock (cattle, horses) can cause economic losses for producers. Management strategies include maintaining livestock in fenced, -free pastures or barns from September to May; spring plowing of infested fields to bury engorged females and prevent larval ; and arsenical dips for infested animals (with temperature restrictions in northern regions). The serves as a case study for climate-wildlife- interactions and in wildlife contexts.

Similar Taxa

Dermacentor variabilis (American dog tick)Three- versus one-host in D. albipictus; active spring through summer versus autumn-winter activity; of and versus no known transmission in D. albipictus; different spiracular plate
Dermacentor andersoni (Rocky Mountain wood tick)Three- restricted to western North America; of and ; differs in geographic range and
Amblyomma americanum (Lone Star tick)Three- with different host range; aggressive human biter; transmits , STARI, and other ; active spring through summer; distinct white spot on female

More Details

Climate sensitivity

Warmer and shorter winters correlate with increased survival and higher rates on moose, contributing to declines in the southern half of the eastern moose range.

Genetic variation

Deep mitochondrial lineage divergences (7.1% COI, 4.5% 16S) occur within Alberta , but nuclear markers, endosymbionts, and support single status, highlighting the importance of integrative .

Sex determination

Recent transcriptome analysis identified the first documented case of sex-specific splicing of a doublesex-like gene in chelicerates, suggesting ticks share more insect-like features of sexual differentiation than previously recognized.