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Ticks on Dartmoor

Dedicated web site: Dartmoor Tick Watch

Diagram showing the relative size of tick stages
on the human finger nail.
Image reproduced with permission
from Lyme Disease Action

Ticks are part-time external parasites on warm-blooded animals. They are found especially on bracken and in grassland where it grows (see Bracken on Dartmoor). They are not insects in that they are not members of the arthropodan Class Insecta: they belong to the Class Arachnida and are related most closely to spiders, mites and scorpions. They are said to be becoming more common.

Ticks can harbour several diseases that they pass on while feeding, which they do by sucking blood from warm-blooded animals. The diseases are caused variously by protozoa, bacteria and viruses contained in the saliva and gut of the tick - for this reason it is important not to squeeze a tick while removing it, otherwise the gut contents and its pathogens will be injected into the host.

Ticks are external parasites on sheep, deer, dogs and most birds and mammals, including farm animals, and occasionally on man. They are commonly found on grassland where animals feed and in leaf-litter.

Many ticks have a three-host life cycle after the eggs are laid in the soil:

1. The eggs hatch into six-legged larvae in the leaf-litter. These climb vegetation in Spring, waiting for a warm-blooded animal to come along (1st host). After feeding (on blood), the larva drops off.

2. The larva moults into an eight-legged nymph. The nymph then climbs up vegetation and waits for another warm-blooded animal (2nd host), on which to feed and drop off again.

3. After moulting into an eight-legged adult, the tick once again climbs vegetation to wait for another warm-blooded animal (3rd host).
   NB - Bracken is an excellent plant for ticks to climb and find hosts from!

Mating usually takes place on the host after which the female drops off and lays thousands of eggs (there is high mortality). Both adults die after mating (Source: The Life Cycle of the Tick).

The aim of this web page is to illustrate larval, nymph and adult stages (both male & female) in the tick life cycle. The obvious tick on Dartmoor is Ixodes ricinus, the Sheep tick: others will be looked for.

Standard collection methods for entymology will be used: muslin flags, beating sheets and sweep nets.

From the Lyme Disease Action web site: 

• "Three of the diseases that can be caught from a tick bite in Britain are Lyme borreliosis, Babesiosis and Ehrlichiosis" ..... and .....

• "Some ticks carry all three of the above diseases at the same time and can transfer them to you in a single bite. The resulting symptoms can be extremely confusing and liable to misdiagnosis. Treatment in such cases is very difficult."
   

Ticks (Ixodes ricinus - Sheep Tick, Castor Bean Tick or Pasture Tick) removed from a dog on Dartmoor, 25 June 2008 .....

Living ticks 2 females (left, larger) & 2 males (right, smaller)	The two males - 2.1 & 2.5 mm total body lengths
The two females, 3.2 & 3.5 mm total body lengths	All four ticks (dead) Mixture of dorsal and ventral views
Living female tick Note: 8 legs, like a spider, not 6, like a true insect, also the lack of head appendages which would interfere with burrowing into the host's skin   Ixodes ricinus - complete life cycle stages Ixodes ricinus - fed (engorged) female The above two photos: Reproduced with permission of the Natural History Collections of the University of Edinburgh, Photographer Alan R. Walker, Copyright The University of Edinburgh. Other ticks occur in the UK, namely Dermacentor reticulatus (Marsh Tick, Meadow Tick) and Rhipicephalus sanguineus (Kennel Tick,Brown Dog Tick)

The following information is taken from the online Tick Identification Key, with kind permission from Frank Ruedisueli .....

It is a synopsis that mentions several ticks, genera and species but it is not exhaustive - the following section concentrates mainly on ticks found in the UK (highlighted in yellow).

• Argasidae - soft ticks - 5 genera known worldwide: Argas, Ornithodorus, Otobius, Antricola and Nothoaspis - 3 species are found in Europe, namely: Argas reflexus (pigeon tick), Argas vespertilionis and Ornithodorus maritimus.
  These ticks are nidicolous, which means they inhabit the hosts nest. The pigeon tick is occasionally found on other birds and accidentally on man. It causes several diseases.

• Ixodidae, hard ticks - generally not nidicolous except for Ixodes, include .....

  • Amblyomma - not in UK

  • Boophilus - not in UK

  • Ixodes

    • Ixodes ricinus (castor bean tick) - Woodlands, heath lands, forests and bushes: hosts - sheep, cattle, dogs, deer, men, horses. Causes several diseases in animals; in man - Borrelia burgdorferi (Lyme disease), Louping ill, Coxiella burnetii (Q fever),Tick borne encephalitis.

    • Ixodes canisuga (British dog tick, fox tick) - Kennels and burrows: hosts - medium to large mammals: fox, badgers, mink, dogs, cats. Causes Babesia missiroli in badgers and plague in Russia.

    • Ixodes trianguliceps (vole tick) - Humid forests: hosts - bank vole, shrews, mice, rats and voles, accidentally on man and horses. Causes several diseases in Europe and Louping Ill in the UK.

  • Dermacentor reticulatus (marsh tick or ornate cow tick) - Meadows, grasslands, pastures, deciduous mixed forests and woodlands: hosts - sheep, cattle, dogs, pigs , horses and man. Causes - Dogs: Babesia canis, Cattle: Babesia divergens (redwater), B. ovis, Theileria ovis, Coxiella burnetii (Q fever), Francisella tularensis (tularemia), Brucella, Rickettsia conorii (Boutonneuse fever), Horses: Babesia caballi, B. equi, infectious encephalomyelitis of horses, Man: Russian spring summer encephalitis, (RSSE), Omsk haemorrhagic fever (OHF).

  • Haemaphysalis punctata (red sheep tick) - in diverse environments, only in England and Wales in UK : hosts - deer, sheep, cattle, horses, dogs, hedgehogs, goats, hares, mustelids and occasionally on man. Causes several diseases but not noted in the key re. UK human problems.

  • Rhipicephalus sanguineus (brown dog tick) - found worldwide: hosts - dogs. Causes - twelve diseases listed in the Tick Identification Key.

  • Hyalomma - not in UK? Some records for NW Europe of young stages travelling on birds.
    also - Aponnoma, Margaropus, Nosomma, Rhipicentor, Cosmiomma and Anomalohimalaya - all rare

• Nutalliellidae - 1 species only, found in Africa

Links to .....

• Bracken on Dartmoor - describing the problem of its spread, involving toxicity and ticks

• Bracken control on Dartmoor - as practised by Dartmoor Preservation Association, describing the problem of its spread, involving toxicity and ticks

General tick links

• BBC News - Rising risk of UK ticks

• BRC - Biological Records Centre ***

• Borreliosis and Associated Diseases Awareness UK

• Collecting and preserving insects and arachnids - excellent - identification key - collecting methods ***

• Dealing with Deer ticks - Deer tick information from Connecticut, USA ***

  • Tick pictures ***

  • The Deer tick up close ***

• Exmoor Ponies in Conservation - Guide to Equine Parasites

• HPA - Health Protection Agency - Tick Recording Scheme

  • HPA - Press Release 12 Feb 2008 - The Health Effects of Climate Change in the UK
    Quote: "Tick-borne diseases such as Lyme disease are likely to become more common due to changes in land management and an increase in outside leisure time."

• ICTTD - Integrated Consortium on Ticks & Tick-borne Diseases

  • ICTTD Virtual Tick Museum ***

• Identification and Treatment of Ectoparasites in Sheep

• Journal of Clinical Pathology - Identification of Borrelia burgdorferi genomic groups from Scottish ticks

• Kendall Bioresearch Services - Mites & ticks

• Lyme Disease Action shop - tick removers - sells both the Tick Twister and Trix Tick Lassoo linked below

• Microscopy UK - Why ticks are so tricky! - stereo photos

• Moredun Foundation - originally the Animal Diseases Research Association (1920)

• NBN - National Biodiversity Network - searchable data base with distribution maps ***

• O'Tom Hook Tick Twister for removing ticks - widely available from vets

• Practical Parasitology - Introduction to the Hard Bodied Ticks and Lyme Disease - Canada/USA ***

• The Tick Collection - University of Edinburgh

• The Tick-L links page 

• Tick Alert - travel advice for UK and Europe

• Tick Identification Key - excellent - developed at the University of Lincoln, UK ***

• Tick Remover.com - the Trix Tick Lassoo

• Tick repellents

  • Nontix - using dried marigolds in bags pinned to socks or gaiters

  • BADA - Calendula oil - £5.50 per 45 ml bottle (UK only)

  • Frontline - from your vet, for cats and dogs

  • Skudo Electronic Tick rerpeller - attaches to a collar, £12.99, effective up to 1 year

  • DEET - spray-on repellent, different strengths, e.g. £4.39 per 50 ml spray. Options include a version with natural pyrethroids and one with citrus (lemon eucalyptus extract).

• Ticks feeding on humans: a review of records on human-biting Ixodoidea with special reference to pathogen transmission - worldwide review of records

   

Lyme and other tick disease links

• Babesiosis

• BBC News - Tick disease warning to doctors - Quote: "It is caused by the bacterium Borrelia burgdorferi and is transmitted to humans by the bite of infected ticks" & "Doctors may see increasing numbers of cases of Lyme disease in the future as recent news reports have indicated a rise in the tick population"

• BBC News - Walkers warned of a killer insect - Quote: "Government statistics show that cases of Lyme Disease in Scotland have risen from two in 1992 to 85 last year, although so far no one has died." Also: "The Highlands also has one of the highest rates of the disease in northern Europe, with 16 cases per 100,000 people." This was dated Aug. 2003. Lyme Disease is a notifiable disease only in Scotland.

• Borreliosis & Associated Diseases Awareness UK - A wealth of information about ticks and the diseases they can carry. Particularly, follow the Learn more links.

• British Lyme Disease Foundation - Presenting details on Lyme Disease & other Tick-borne Diseases for the UK - excellent - UK-specific ***

• Ehrlichiosis - generally in dogs but cats and humans can be infected

• EuroLyme - Lyme Disease Support Group - a free newsgroup to which you have to enrol

• Is Lyme disease worldwide? - "The HPA also notes that “incidents of Lyme Disease have increased by 90% since 2006 across the UK, ....."
  This HPA document reports "A provisional total of three hundred and fifty-five reports, up to the end of August 2005, have been received, compared with an annual average of 215 reports during the same period from 2001 to 2004." This works out to a 65% increase. Presumably the rest of the year brought more cases? (Ed.)

• Louping Ill - a disease affecting sheep and other domestic animals as well as man

• Lyme Disease - Association of Medical Microbiologists (USA)

• Lyme Disease Action.org.uk/ 2007 Conference, some good disease-related links ***

• Lyme Disease Action.org.uk - Ticks - Lyme disease & other tick borne diseases in Britain

• Lyme Disease Action - UK Ticks - "All the ticks on this page were collected in Devon" ***

• Lyme Disease and ticks - on The Countrylovers Website

• Lyme Disease Network (USA)

• Lyme Disease Surveillance in England and Wales, 1986-1998

• Lyme is a Biowarfare Issue ***

• netdoctor.co.uk - Lyme Disease

• NHS Choices - Lyme Disease

• Scotland - Ticks and Lymes disease (Lyme disease is a notifiable disease in Scotland) - "We must also not lose sight of the risk to human health from Lyme disease, with 1000 human cases of Lyme disease in 2006."

• Statistics by country for Lyme disease

• Tick-borne meningoencephalitis - Russia and Europe report 10-12,000 cases each year

• Ticks and Lyme Disease

• Under our skin - documentary about Lyme, the biggest epidemic after AIDS

• wrongdiagnosis - Llyme_disease

Working notes .....

Scource: http://www.bioimages.org.uk/HTML/T76116.HTM - Hard ticks .....

• Species: Dermacentor reticulatus (Fabricius, 1794) (Marsh Tick, Ornate Cow Tick)

• Species: Haemaphysalis punctata Canestrini & Fanzago, 1877 (Coastal Red Tick, Red Sheep Tick)

• Species: Hyalomma aegyptium (Linne, 1758) (Tortoise Tick)

• Species: Hyalomma marginatum Koch, C.L., 1844 (Two-host Tick)

• Genus: Ixodes Latreille, 1795 (hard ticks)

• Species: Ixodes acuminatus Neumann, 1901 (a hard tick)

• Species: Ixodes canisuga Johnston, 1849 (Fox Tick)

• Species: Ixodes hexagonus Leach, 1815 (Hedgehog Tick)

• Species: Ixodes ricinus (Linnaeus, 1758) (Sheep Tick, Pasture Tick, Castor Bean Tick, Deer Tick)

• Species: Ixodes trianguliceps Birula, 1895 (Vole or Shrew Tick)

• Species: Ixodes uriae White, 1852 (Seabird Tick)

• Species: Ixodes ventalloi Gil Collado, 1936 (Rabbit Tick)

• Species: Rhipicephalus sanguineus Latreille, 1806 (Kennel or Brown Dog Tick)

Source: http://www.bioimages.org.uk/HTML/T96782.HTM - Soft ticks .....

• Species: Argas reflexus (Fabricius, 1794) (Canterbury or Pigeon Tick)

• Species: Argas vespertilionis (Short-legged Bat Tick)