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Ixodes pacificus

Ixodes pacificus, the western black-legged tick, is a species of parasitic tick found on the western coast of North America. I. pacificus is a member of the family Ixodidae (hard ticks). It is the principal vector of Lyme disease in that region. I. pacificus larvae and nymphs typically feeds on lizards and small mammals, while adults typically feed on deer.[1] It is an ectoparasite that attaches itself to the outside of its host and feeds on the host's blood. It can have a heteroxenous lifestyle or monoxenous life cycle depending on how many hosts it feeds on in each cycle.[2] I. pacificus has a four stage life cycle that takes around 3 years to complete. These stages include egg, larva, nymph, and adult.[3] They prefer dense woodland habitats or areas of brush and tall grass.[4]

Ixodes pacificus
Adult female western black-legged tick
Scientific classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Arthropoda
Subphylum: Chelicerata
Class: Arachnida
Order: Ixodida
Family: Ixodidae
Genus: Ixodes
Species:
I. pacificus
Binomial name
Ixodes pacificus
Cooley & Kohls, 1943

Description edit

Belonging to the family Ixodidae, the western black-legged tick is considered a slow-feeding hard tick which possesses a plated body armor.[5] It is primarily found in the western region of the United States, particularly in northern California,[6] and in western Canada.

An adult male is around 2.54 mm in size, oval-shaped, and brownish-black in color. Due to the presence of a hard plate or scutum that completely covers the dorsal side of the male, they are unable to feed in large quantities. Therefore, males of this species are unable to become engorged.[7][8]

An unfed adult female is around 3.18 mm in size, has a brown-black scutum on the anterior back, an orange abdomen, and forward-projecting mouth-parts which enable feeding. While feeding, the adult female may engorge and expand to 9.5 mm or longer.[5]

Range edit

Ixodes pacificus is found in the western region of the United States and in western Canada. Although most prevalent in California, the tick has also been found in five other western states. These include Oregon, Washington, Utah, Nevada, and Arizona.[9] I. pacificus has also been recorded in British Columbia.[10]

Habitat edit

Nymphs edit

Nymphal stage ticks prefer a habitat consisting of dense woodlands with many leaves and areas littered with fir needles. It is most common to encounter western black-legged tick nymphs in areas with large amounts of shed leaves on the ground. This life stage of the tick may be encountered when humans are in direct contact with logs, branches, and shed leaves. These locations are where nymphal ticks seek out hosts.[5]

Adults edit

Both adult females and males prefer a habitat with an abundance of short vegetation. They may be found in grasslands, woodland grass, or brush areas. Unlike nymphal ticks, adult western black-legged ticks prefer to climb vegetation and wait for hosts to pass by. As such, these ticks are commonly encountered in open grasslands, at the border of trails in parklands, and in areas that are able to maintain a deer population.[5]

Life cycle edit

The life cycle of Ixodes pacificus consists of four life stages: egg, larva, nymph, and adult. It takes approximately three years for the tick to complete its life cycle.[11]

Larvae, which emerge from eggs after approximately 53–55 days, take blood meals from vertebrates, such as lizards and birds. Protein from the blood meals, during the 4-10 day feeding period, enable the larvae to transform into immature nymphs after approximately 37–38 days.[7] In order for the nymph to reach the adult stage, they continue to feed for 7–11 days on the blood of vertebrates. After 30 days, an adult tick emerges. Female adults will consume blood meals from medium and large-sized mammals, and then deposit eggs in areas of leaf litter or soil.[9] Female adult ticks can deposit between 790 and 1,300 eggs over a period of 33–40 days.[7]

Disease transmission edit

The western black-legged tick is a vector for Lyme disease, which is caused by infection with Borrelia burgdorferi. After feeding on a host animal infected with the bacterium, the tick is then able to transmit it to other animals, including humans, through subsequent blood meals. The nymphal stage, and sometimes adult female ticks, are responsible for the majority of transmission events. Nymphal ticks primarily feed on small animals and humans during the spring and early summer, while adult ticks are most active during the winter and seek out hosts from late fall to spring.[5]

In order for a human to be infected by the bacterium, the tick carrying it must be attached for approximately 36 to 48 hours. Due to the smaller size of the nymphal stage ticks, approximately 2 mm, they are more likely to go unnoticed when attached to a human. This enables a nymph to potentially stay attached longer to the host it is feeding on. For this reason, the nymphal stage is primarily responsible for transmission of Borrelia burgdorferi.[12]

Attachment mechanism edit

Once a tick finds itself on its host it will immediately begin to look for an appropriate feeding site. Finding a site to feed typically takes a little as 10 minutes but can last as long as 2 hours. When the tick finds a sufficient feeding location it punctures the skin of its host and inserts a feeding tube that secretes a cement like substance and has barbs to help the tick to stay attached to the host. Ticks also secrete saliva onto the punctured area that acts as anesthetic so the host will not feel the tick cutting into the skin. This allows the tick to stay attached to the host longer because they go unnoticed by the host. Once a tick is attached it will then feed on the hosts blood meal for several days and then detach itself from the host. If the tick was infected with a pathogen it may transmit the infection to the host species through its saliva entering the host's blood stream.[1]

References edit

  1. ^ a b CDC (2019-01-10). "Geographic distribution of ticks that bite humans | CDC". Centers for Disease Control and Prevention. Retrieved 2020-02-28.
  2. ^ Maruyama, Sandra R; Anatriello, Elen; Anderson, Jennifer M; Ribeiro, José M; Brandão, Lucinda G; Valenzuela, Jesus G; Ferreira, Beatriz R; Garcia, Gustavo R; Szabó, Matias PJ; Patel, Sonal; Bishop, Richard (2010). "The expression of genes coding for distinct types of glycine-rich proteins varies according to the biology of three metastriate ticks, Rhipicephalus (Boophilus) microplus, Rhipicephalus sanguineus and Amblyomma cajennense". BMC Genomics. 11 (1): 363. doi:10.1186/1471-2164-11-363. PMC 2901319. PMID 20529354.
  3. ^ Padgett, Kerry A.; Lane, Robert S. (2001-09-01). "Life Cycle of Ixodes pacificus (Acari: Ixodidae): Timing of Developmental Processes Under Field and Laboratory Conditions". Journal of Medical Entomology. 38 (5): 684–693. doi:10.1603/0022-2585-38.5.684. PMID 11580041. S2CID 24100268.
  4. ^ "Lyme Disease", Dynamic Modeling of Diseases and Pests, Springer New York, pp. 115–136, 2009, doi:10.1007/978-0-387-09560-8_7, ISBN 978-0-387-09559-2
  5. ^ a b c d e Lyme Disease in California, Lane, RS and Kjemtrup, AM, University of California Agriculture and Natural Resources, 2016.
  6. ^ Western blacklegged tick(Ixodes pacificus), Center for Disease Control and Prevention
  7. ^ a b c Arthur, DR; Snow, KR (1968). "Ixodes pacificus Cooley and Kohls, 1943: its life-history and occurrence". Parasitology. 58 (4): 893–906. doi:10.1017/S0031182000069663. PMID 5693986.
  8. ^ "Ixodes scapularis and Ixodes pacificus". Companion Animal Parasite Council. 1 July 2015. Retrieved 11 April 2024.
  9. ^ a b Eisen, RJ; Beard, CB (2016). "County-scale distribution of Ixodes scapularis and Ixodes pacificus (Acari: Ixodidae) in the continental United States". Journal of Medical Entomology. 53 (2): 349–386. doi:10.1093/jme/tjv237. PMC 4844559. PMID 26783367.
  10. ^ "Ticks and Lyme Disease". www.interiorhealth.ca. Retrieved 2018-05-11.
  11. ^ Padgett, KA; Lane, RS (2001). "Life cycle of Ixodes pacificus (Acari: Ixodidae): timing of developmental processes under field and laboratory conditions". Journal of Medical Entomology. 38 (5): 684–693. doi:10.1603/0022-2585-38.5.684. PMID 11580041. S2CID 24100268.
  12. ^ "Transmission - Lyme Disease". Centers for Disease Control and Prevention. 2019-02-06.

External links edit

  •   Media related to Ixodes pacificus at Wikimedia Commons

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Ixodes pacificus the western black legged tick is a species of parasitic tick found on the western coast of North America I pacificus is a member of the family Ixodidae hard ticks It is the principal vector of Lyme disease in that region I pacificus larvae and nymphs typically feeds on lizards and small mammals while adults typically feed on deer 1 It is an ectoparasite that attaches itself to the outside of its host and feeds on the host s blood It can have a heteroxenous lifestyle or monoxenous life cycle depending on how many hosts it feeds on in each cycle 2 I pacificus has a four stage life cycle that takes around 3 years to complete These stages include egg larva nymph and adult 3 They prefer dense woodland habitats or areas of brush and tall grass 4 Ixodes pacificus Adult female western black legged tick Scientific classification Domain Eukaryota Kingdom Animalia Phylum Arthropoda Subphylum Chelicerata Class Arachnida Order Ixodida Family Ixodidae Genus Ixodes Species I pacificus Binomial name Ixodes pacificusCooley amp Kohls 1943 Contents 1 Description 2 Range 3 Habitat 3 1 Nymphs 3 2 Adults 4 Life cycle 4 1 Disease transmission 4 2 Attachment mechanism 5 References 6 External linksDescription editBelonging to the family Ixodidae the western black legged tick is considered a slow feeding hard tick which possesses a plated body armor 5 It is primarily found in the western region of the United States particularly in northern California 6 and in western Canada An adult male is around 2 54 mm in size oval shaped and brownish black in color Due to the presence of a hard plate or scutum that completely covers the dorsal side of the male they are unable to feed in large quantities Therefore males of this species are unable to become engorged 7 8 An unfed adult female is around 3 18 mm in size has a brown black scutum on the anterior back an orange abdomen and forward projecting mouth parts which enable feeding While feeding the adult female may engorge and expand to 9 5 mm or longer 5 Range editIxodes pacificus is found in the western region of the United States and in western Canada Although most prevalent in California the tick has also been found in five other western states These include Oregon Washington Utah Nevada and Arizona 9 I pacificus has also been recorded in British Columbia 10 Habitat editNymphs edit Nymphal stage ticks prefer a habitat consisting of dense woodlands with many leaves and areas littered with fir needles It is most common to encounter western black legged tick nymphs in areas with large amounts of shed leaves on the ground This life stage of the tick may be encountered when humans are in direct contact with logs branches and shed leaves These locations are where nymphal ticks seek out hosts 5 Adults edit Both adult females and males prefer a habitat with an abundance of short vegetation They may be found in grasslands woodland grass or brush areas Unlike nymphal ticks adult western black legged ticks prefer to climb vegetation and wait for hosts to pass by As such these ticks are commonly encountered in open grasslands at the border of trails in parklands and in areas that are able to maintain a deer population 5 Life cycle editThe life cycle of Ixodes pacificus consists of four life stages egg larva nymph and adult It takes approximately three years for the tick to complete its life cycle 11 Larvae which emerge from eggs after approximately 53 55 days take blood meals from vertebrates such as lizards and birds Protein from the blood meals during the 4 10 day feeding period enable the larvae to transform into immature nymphs after approximately 37 38 days 7 In order for the nymph to reach the adult stage they continue to feed for 7 11 days on the blood of vertebrates After 30 days an adult tick emerges Female adults will consume blood meals from medium and large sized mammals and then deposit eggs in areas of leaf litter or soil 9 Female adult ticks can deposit between 790 and 1 300 eggs over a period of 33 40 days 7 Disease transmission edit The western black legged tick is a vector for Lyme disease which is caused by infection with Borrelia burgdorferi After feeding on a host animal infected with the bacterium the tick is then able to transmit it to other animals including humans through subsequent blood meals The nymphal stage and sometimes adult female ticks are responsible for the majority of transmission events Nymphal ticks primarily feed on small animals and humans during the spring and early summer while adult ticks are most active during the winter and seek out hosts from late fall to spring 5 In order for a human to be infected by the bacterium the tick carrying it must be attached for approximately 36 to 48 hours Due to the smaller size of the nymphal stage ticks approximately 2 mm they are more likely to go unnoticed when attached to a human This enables a nymph to potentially stay attached longer to the host it is feeding on For this reason the nymphal stage is primarily responsible for transmission of Borrelia burgdorferi 12 Attachment mechanism edit Once a tick finds itself on its host it will immediately begin to look for an appropriate feeding site Finding a site to feed typically takes a little as 10 minutes but can last as long as 2 hours When the tick finds a sufficient feeding location it punctures the skin of its host and inserts a feeding tube that secretes a cement like substance and has barbs to help the tick to stay attached to the host Ticks also secrete saliva onto the punctured area that acts as anesthetic so the host will not feel the tick cutting into the skin This allows the tick to stay attached to the host longer because they go unnoticed by the host Once a tick is attached it will then feed on the hosts blood meal for several days and then detach itself from the host If the tick was infected with a pathogen it may transmit the infection to the host species through its saliva entering the host s blood stream 1 References edit a b CDC 2019 01 10 Geographic distribution of ticks that bite humans CDC Centers for Disease Control and Prevention Retrieved 2020 02 28 Maruyama Sandra R Anatriello Elen Anderson Jennifer M Ribeiro Jose M Brandao Lucinda G Valenzuela Jesus G Ferreira Beatriz R Garcia Gustavo R Szabo Matias PJ Patel Sonal Bishop Richard 2010 The expression of genes coding for distinct types of glycine rich proteins varies according to the biology of three metastriate ticks Rhipicephalus Boophilus microplus Rhipicephalus sanguineus and Amblyomma cajennense BMC Genomics 11 1 363 doi 10 1186 1471 2164 11 363 PMC 2901319 PMID 20529354 Padgett Kerry A Lane Robert S 2001 09 01 Life Cycle of Ixodes pacificus Acari Ixodidae Timing of Developmental Processes Under Field and Laboratory Conditions Journal of Medical Entomology 38 5 684 693 doi 10 1603 0022 2585 38 5 684 PMID 11580041 S2CID 24100268 Lyme Disease Dynamic Modeling of Diseases and Pests Springer New York pp 115 136 2009 doi 10 1007 978 0 387 09560 8 7 ISBN 978 0 387 09559 2 a b c d e Lyme Disease in California Lane RS and Kjemtrup AM University of California Agriculture and Natural Resources 2016 Western blacklegged tick Ixodes pacificus Center for Disease Control and Prevention a b c Arthur DR Snow KR 1968 Ixodes pacificus Cooley and Kohls 1943 its life history and occurrence Parasitology 58 4 893 906 doi 10 1017 S0031182000069663 PMID 5693986 Ixodes scapularis and Ixodes pacificus Companion Animal Parasite Council 1 July 2015 Retrieved 11 April 2024 a b Eisen RJ Beard CB 2016 County scale distribution of Ixodes scapularis and Ixodes pacificus Acari Ixodidae in the continental United States Journal of Medical Entomology 53 2 349 386 doi 10 1093 jme tjv237 PMC 4844559 PMID 26783367 Ticks and Lyme Disease www interiorhealth ca Retrieved 2018 05 11 Padgett KA Lane RS 2001 Life cycle of Ixodes pacificus Acari Ixodidae timing of developmental processes under field and laboratory conditions Journal of Medical Entomology 38 5 684 693 doi 10 1603 0022 2585 38 5 684 PMID 11580041 S2CID 24100268 Transmission Lyme Disease Centers for Disease Control and Prevention 2019 02 06 External links edit nbsp Media related to Ixodes pacificus at Wikimedia Commons Retrieved from https en wikipedia org w index php title Ixodes pacificus amp oldid 1219994357, wikipedia, wiki, book, books, library,

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