Ixodes ricinus
Encyclopedia
Ixodes ricinus, the castor bean tick, is a chiefly Europe
an species of hard-bodied tick
. It may reach a length of 11 mm (0.433070866141732 in) when engorged with a blood meal, and can transmit both bacterial and viral pathogen
s such as the causative agents of Lyme disease
and tick-borne encephalitis.
, I. ricinus has no eyes and is not ornate; it has no festoons (wrinkles along the posterior margin). The palpi are longer than they are wide, and there is an anal groove above the anus
. It has a hard dorsal shield which covers the entire opisthosoma
(abdomen), but only part of it in females and nymphs. I. ricinus is the largest of the three common species of Ixodes in the British Isles
(the other two being I.canisuga, the "British dog tick", and I. trianguliceps, the "vole tick"). Adult males are 2.4–2.8 mm (0.094488188976378–0.110236220472441 ) long, and unfed nymphs are 1.3–1.5 mm (0.0511811023622047–0.0590551181102362 ) long; females are 3–3.6 mm (0.118110236220472–0.141732283464567 ) long before feeding and 11 millimetre (0.433070866141732 in) long when engorged.
and into neighbouring parts of North Africa
and the Middle East
, extending as far north as Iceland
and as far east as parts of Russia
. Its northern limit seems to be determined by environmental
factors, including temperature
, since a series of mild winters in Scandinavia
coincided with an expansion northwards in the range of I. ricinus.
I. ricinus is most frequent in habitats where its hosts are plentiful, including woodland
s, heaths
and forest
s. It is most prevalent in relatively humid areas, and is absent from much of the Mediterranean Region
where summers are dry.
, which usually takes 2–3 years to complete, although it can take from 1 to 6 years in extreme cases. Adults feed on large mammals such as sheep, cattle
, dog
s, deer
, human
s and horse
s for 6–13 days, before dropping off. An engorged female will lay several thousand eggs and subsequently die. The larva
e that hatch do not actively seek a host, and usually feed on insectivores
(orders Erinaceomorpha and Soricomorpha
), although they may also find rodent
s, rabbit
s, bird
s reptile
s or bat
s. They feed for 3–5 days before dropping off and moulting
. The resulting nymphs then ascend grass
es or twigs to seek their next host, but must return to the moist microclimate
at the soil surface if they become dehydrated
. The nymphs
feed on small to medium-sized mammals.
s can be transmitted by I. ricinus to a variety of mammal
hosts. Dog
s can be infected with Lyme disease
(borreliosis), caused by the spirochaete
bacteria
Borrelia burgdorferi
, B. afzeli and B. garnii. Cattle
can become infected with redwater fever
(from the protozoans Babesia divergens
, B. bovis
and B. ovis), Lyme disease (from Borrelia burgdorferi
), sheep tick pyemia (Staphylococcus aureus
), cattle tick-borne fever (Anaplasma phagocytophila), Q fever
(Coxiella burnetii
), Boutonneuse fever
(Rickettsia conorii
) and the bacterium Anaplasma marginale. Horse
s may be infected with Lyme disease, Anaplasma phagocytophila, and the viral infection "louping ill
". Humans can become infected with Lyme disease, louping ill, Q fever and tick-borne encephalitis.
of the castor bean tick dates back to the starting point of zoological nomenclature, the 1758 tenth edition of Carl Linnaeus' Systema Naturae
, where it appeared as Acarus ricinus. Pierre André Latreille
split the new genus Ixodes
from Linnaeus' Acarus
(which at that time contained all known ticks and mite
s), and I. ricinus was chosen as the type species
. It has subsequently been redescribed under a number of junior synonyms and subsequent combinations into different genera; these synonyms include Acarus ricinoides, Cynorhaestes reduvius, Cynorhaestes ricinus, Ixodes megathyreus, Ixodes bipunctatus, Cynorhaestes hermanni, Crotonus ricinus, Ixodes trabeatus, Ixodes plumbeus, Ixodes reduvius, Ixodes pustularum, Ixodes fodiens, Ixodes rufus, Ixodes sulcatus and Ixodes sciuri.
Europe
Europe is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally 'divided' from Asia to its east by the watershed divides of the Ural and Caucasus Mountains, the Ural River, the Caspian and Black Seas, and the waterways connecting...
an species of hard-bodied tick
Tick
Ticks are small arachnids in the order Ixodida, along with mites, constitute the subclass Acarina. Ticks are ectoparasites , living by hematophagy on the blood of mammals, birds, and sometimes reptiles and amphibians...
. It may reach a length of 11 mm (0.433070866141732 in) when engorged with a blood meal, and can transmit both bacterial and viral pathogen
Pathogen
A pathogen gignomai "I give birth to") or infectious agent — colloquially, a germ — is a microbe or microorganism such as a virus, bacterium, prion, or fungus that causes disease in its animal or plant host...
s such as the causative agents of Lyme disease
Lyme disease
Lyme disease, or Lyme borreliosis, is an emerging infectious disease caused by at least three species of bacteria belonging to the genus Borrelia. Borrelia burgdorferi sensu stricto is the main cause of Lyme disease in the United States, whereas Borrelia afzelii and Borrelia garinii cause most...
and tick-borne encephalitis.
Description
In common with other species of IxodesIxodes
Ixodes is a genus of hard-bodied ticks . It includes important disease vectors of animals and humans . Some ticks in this genus may transmit the pathogenic bacterium Borrelia burgdorferi responsible for causing Lyme disease...
, I. ricinus has no eyes and is not ornate; it has no festoons (wrinkles along the posterior margin). The palpi are longer than they are wide, and there is an anal groove above the anus
Anus
The anus is an opening at the opposite end of an animal's digestive tract from the mouth. Its function is to control the expulsion of feces, unwanted semi-solid matter produced during digestion, which, depending on the type of animal, may be one or more of: matter which the animal cannot digest,...
. It has a hard dorsal shield which covers the entire opisthosoma
Opisthosoma
The opisthosoma is the posterior part of the body in some arthropods, behind the prosoma . It is a distinctive feature of the subphylum Chelicerata...
(abdomen), but only part of it in females and nymphs. I. ricinus is the largest of the three common species of Ixodes in the British Isles
British Isles
The British Isles are a group of islands off the northwest coast of continental Europe that include the islands of Great Britain and Ireland and over six thousand smaller isles. There are two sovereign states located on the islands: the United Kingdom of Great Britain and Northern Ireland and...
(the other two being I.canisuga, the "British dog tick", and I. trianguliceps, the "vole tick"). Adult males are 2.4–2.8 mm (0.094488188976378–0.110236220472441 ) long, and unfed nymphs are 1.3–1.5 mm (0.0511811023622047–0.0590551181102362 ) long; females are 3–3.6 mm (0.118110236220472–0.141732283464567 ) long before feeding and 11 millimetre (0.433070866141732 in) long when engorged.
Distribution
Ixodes ricinus is found across EuropeEurope
Europe is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally 'divided' from Asia to its east by the watershed divides of the Ural and Caucasus Mountains, the Ural River, the Caspian and Black Seas, and the waterways connecting...
and into neighbouring parts of North Africa
North Africa
North Africa or Northern Africa is the northernmost region of the African continent, linked by the Sahara to Sub-Saharan Africa. Geopolitically, the United Nations definition of Northern Africa includes eight countries or territories; Algeria, Egypt, Libya, Morocco, South Sudan, Sudan, Tunisia, and...
and the Middle East
Middle East
The Middle East is a region that encompasses Western Asia and Northern Africa. It is often used as a synonym for Near East, in opposition to Far East...
, extending as far north as Iceland
Iceland
Iceland , described as the Republic of Iceland, is a Nordic and European island country in the North Atlantic Ocean, on the Mid-Atlantic Ridge. Iceland also refers to the main island of the country, which contains almost all the population and almost all the land area. The country has a population...
and as far east as parts of Russia
Russia
Russia or , officially known as both Russia and the Russian Federation , is a country in northern Eurasia. It is a federal semi-presidential republic, comprising 83 federal subjects...
. Its northern limit seems to be determined by environmental
Natural environment
The natural environment encompasses all living and non-living things occurring naturally on Earth or some region thereof. It is an environment that encompasses the interaction of all living species....
factors, including temperature
Temperature
Temperature is a physical property of matter that quantitatively expresses the common notions of hot and cold. Objects of low temperature are cold, while various degrees of higher temperatures are referred to as warm or hot...
, since a series of mild winters in Scandinavia
Scandinavia
Scandinavia is a cultural, historical and ethno-linguistic region in northern Europe that includes the three kingdoms of Denmark, Norway and Sweden, characterized by their common ethno-cultural heritage and language. Modern Norway and Sweden proper are situated on the Scandinavian Peninsula,...
coincided with an expansion northwards in the range of I. ricinus.
I. ricinus is most frequent in habitats where its hosts are plentiful, including woodland
Woodland
Ecologically, a woodland is a low-density forest forming open habitats with plenty of sunlight and limited shade. Woodlands may support an understory of shrubs and herbaceous plants including grasses. Woodland may form a transition to shrubland under drier conditions or during early stages of...
s, heaths
Heath (habitat)
A heath or heathland is a dwarf-shrub habitat found on mainly low quality acidic soils, characterised by open, low growing woody vegetation, often dominated by plants of the Ericaceae. There are some clear differences between heath and moorland...
and forest
Forest
A forest, also referred to as a wood or the woods, is an area with a high density of trees. As with cities, depending where you are in the world, what is considered a forest may vary significantly in size and have various classification according to how and what of the forest is composed...
s. It is most prevalent in relatively humid areas, and is absent from much of the Mediterranean Region
Mediterranean Basin
In biogeography, the Mediterranean Basin refers to the lands around the Mediterranean Sea that have a Mediterranean climate, with mild, rainy winters and hot, dry summers, which supports characteristic Mediterranean forests, woodlands, and scrub vegetation...
where summers are dry.
Life cycle
Ixodes ricinus has a three-host life cycleBiological life cycle
A life cycle is a period involving all different generations of a species succeeding each other through means of reproduction, whether through asexual reproduction or sexual reproduction...
, which usually takes 2–3 years to complete, although it can take from 1 to 6 years in extreme cases. Adults feed on large mammals such as sheep, cattle
Cattle
Cattle are the most common type of large domesticated ungulates. They are a prominent modern member of the subfamily Bovinae, are the most widespread species of the genus Bos, and are most commonly classified collectively as Bos primigenius...
, dog
Dog
The domestic dog is a domesticated form of the gray wolf, a member of the Canidae family of the order Carnivora. The term is used for both feral and pet varieties. The dog may have been the first animal to be domesticated, and has been the most widely kept working, hunting, and companion animal in...
s, deer
Deer
Deer are the ruminant mammals forming the family Cervidae. Species in the Cervidae family include white-tailed deer, elk, moose, red deer, reindeer, fallow deer, roe deer and chital. Male deer of all species and female reindeer grow and shed new antlers each year...
, human
Human
Humans are the only living species in the Homo genus...
s and horse
Horse
The horse is one of two extant subspecies of Equus ferus, or the wild horse. It is a single-hooved mammal belonging to the taxonomic family Equidae. The horse has evolved over the past 45 to 55 million years from a small multi-toed creature into the large, single-toed animal of today...
s for 6–13 days, before dropping off. An engorged female will lay several thousand eggs and subsequently die. The larva
Larva
A larva is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle...
e that hatch do not actively seek a host, and usually feed on insectivores
Insectivora
The order Insectivora is a now-abandoned biological grouping within the class of mammals...
(orders Erinaceomorpha and Soricomorpha
Soricomorpha
The order Soricomorpha is taxon within the class of mammals. In previous years it formed a significant group within the former order Insectivora...
), although they may also find rodent
Rodent
Rodentia is an order of mammals also known as rodents, characterised by two continuously growing incisors in the upper and lower jaws which must be kept short by gnawing....
s, rabbit
Rabbit
Rabbits are small mammals in the family Leporidae of the order Lagomorpha, found in several parts of the world...
s, bird
Bird
Birds are feathered, winged, bipedal, endothermic , egg-laying, vertebrate animals. Around 10,000 living species and 188 families makes them the most speciose class of tetrapod vertebrates. They inhabit ecosystems across the globe, from the Arctic to the Antarctic. Extant birds range in size from...
s reptile
Reptile
Reptiles are members of a class of air-breathing, ectothermic vertebrates which are characterized by laying shelled eggs , and having skin covered in scales and/or scutes. They are tetrapods, either having four limbs or being descended from four-limbed ancestors...
s or bat
Bat
Bats are mammals of the order Chiroptera "hand" and pteron "wing") whose forelimbs form webbed wings, making them the only mammals naturally capable of true and sustained flight. By contrast, other mammals said to fly, such as flying squirrels, gliding possums, and colugos, glide rather than fly,...
s. They feed for 3–5 days before dropping off and moulting
Ecdysis
Ecdysis is the moulting of the cuticula in many invertebrates. This process of moulting is the defining feature of the clade Ecdysozoa, comprising the arthropods, nematodes, velvet worms, horsehair worms, rotifers, tardigrades and Cephalorhyncha...
. The resulting nymphs then ascend grass
Grass
Grasses, or more technically graminoids, are monocotyledonous, usually herbaceous plants with narrow leaves growing from the base. They include the "true grasses", of the Poaceae family, as well as the sedges and the rushes . The true grasses include cereals, bamboo and the grasses of lawns ...
es or twigs to seek their next host, but must return to the moist microclimate
Microclimate
A microclimate is a local atmospheric zone where the climate differs from the surrounding area. The term may refer to areas as small as a few square feet or as large as many square miles...
at the soil surface if they become dehydrated
Dehydration
In physiology and medicine, dehydration is defined as the excessive loss of body fluid. It is literally the removal of water from an object; however, in physiological terms, it entails a deficiency of fluid within an organism...
. The nymphs
Nymph (biology)
In biology, a nymph is the immature form of some invertebrates, particularly insects, which undergoes gradual metamorphosis before reaching its adult stage. Unlike a typical larva, a nymph's overall form already resembles that of the adult. In addition, while a nymph moults it never enters a...
feed on small to medium-sized mammals.
Disease transmission
A number of tick-borne diseaseTick-borne disease
Tick-borne diseases are diseases or illnesses transmitted by ticks. As the incidence of tick-borne illnesses increases and the geographic areas in which they are found expand, it becomes increasingly important that health professionals be able to distinguish the diverse, and often overlapping,...
s can be transmitted by I. ricinus to a variety of mammal
Mammal
Mammals are members of a class of air-breathing vertebrate animals characterised by the possession of endothermy, hair, three middle ear bones, and mammary glands functional in mothers with young...
hosts. Dog
Dog
The domestic dog is a domesticated form of the gray wolf, a member of the Canidae family of the order Carnivora. The term is used for both feral and pet varieties. The dog may have been the first animal to be domesticated, and has been the most widely kept working, hunting, and companion animal in...
s can be infected with Lyme disease
Lyme disease
Lyme disease, or Lyme borreliosis, is an emerging infectious disease caused by at least three species of bacteria belonging to the genus Borrelia. Borrelia burgdorferi sensu stricto is the main cause of Lyme disease in the United States, whereas Borrelia afzelii and Borrelia garinii cause most...
(borreliosis), caused by the spirochaete
Spirochaete
Spirochaetes belong to a phylum of distinctive Gram-negative bacteria, which have long, helically coiled cells...
bacteria
Bacteria
Bacteria are a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria have a wide range of shapes, ranging from spheres to rods and spirals...
Borrelia burgdorferi
Borrelia burgdorferi
Borrelia burgdorferi is a species of Gram negative bacteria of the spirochete class of the genus Borrelia. B. burgdorferi is predominant in North America, but also exists in Europe, and is the agent of Lyme disease....
, B. afzeli and B. garnii. Cattle
Cattle
Cattle are the most common type of large domesticated ungulates. They are a prominent modern member of the subfamily Bovinae, are the most widespread species of the genus Bos, and are most commonly classified collectively as Bos primigenius...
can become infected with redwater fever
Babesiosis
Babesiosis is a malaria-like parasitic disease caused by infection with Babesia, a genus of protozoal piroplasms. After trypanosomes, Babesia are thought to be the second most common blood parasites of mammals and they can have a major impact on health of domestic animals in areas without severe...
(from the protozoans Babesia divergens
Babesia divergens
Babesia divergens is an intraerythrocytic protozoan parasite, transmitted by the tick Ixodes ricinus. It is the main agent of bovine babesiosis, or "redwater fever", in Europe. Young cattle are less susceptible...
, B. bovis
Babesia bovis
Babesia bovis is a single-celled protozoan parasite of cattle which occasionally infects humans. It is a member of the phylum Apicomplexa, which also includes the malaria parasite. The disease it and other members of the genus Babesia causes is a hemolytic anemia known as Babesiosis and...
and B. ovis), Lyme disease (from Borrelia burgdorferi
Borrelia burgdorferi
Borrelia burgdorferi is a species of Gram negative bacteria of the spirochete class of the genus Borrelia. B. burgdorferi is predominant in North America, but also exists in Europe, and is the agent of Lyme disease....
), sheep tick pyemia (Staphylococcus aureus
Staphylococcus aureus
Staphylococcus aureus is a facultative anaerobic Gram-positive coccal bacterium. It is frequently found as part of the normal skin flora on the skin and nasal passages. It is estimated that 20% of the human population are long-term carriers of S. aureus. S. aureus is the most common species of...
), cattle tick-borne fever (Anaplasma phagocytophila), Q fever
Q fever
Q fever is a disease caused by infection with Coxiella burnetii, a bacterium that affects humans and other animals. This organism is uncommon but may be found in cattle, sheep, goats and other domestic mammals, including cats and dogs...
(Coxiella burnetii
Coxiella burnetii
Coxiella burnetii is an obligate intracellular bacterial pathogen, and is the causative agent of Q fever. The genus Coxiella is morphologically similar to Rickettsia, but with a variety of genetic and physiological differences. C...
), Boutonneuse fever
Boutonneuse fever
Boutonneuse fever is a fever as a result of a Rickettsia infection caused by the bacterium Rickettsia conorii and transmitted by the dog tick Rhipicephalus sanguineus...
(Rickettsia conorii
Rickettsia conorii
Rickettsia conorii is a unicellular, gram-negative, obligate intracellular bacterium of the genus Rickettsia that causes human disease called Boutonneuse fever, Mediterranean spotted fever, Israeli tick typhus, Astrakhan spotted fever, Kenya tick typhus, Indian tick typhus, or other names that...
) and the bacterium Anaplasma marginale. Horse
Horse
The horse is one of two extant subspecies of Equus ferus, or the wild horse. It is a single-hooved mammal belonging to the taxonomic family Equidae. The horse has evolved over the past 45 to 55 million years from a small multi-toed creature into the large, single-toed animal of today...
s may be infected with Lyme disease, Anaplasma phagocytophila, and the viral infection "louping ill
Louping ill
Louping-ill is an acute viral disease primarily of sheep that is characterized by a biphasic fever, depression, ataxia, muscular incoordination, tremors, posterior paralysis, coma, and death...
". Humans can become infected with Lyme disease, louping ill, Q fever and tick-borne encephalitis.
Taxonomic history
The scientific nameBinomial nomenclature
Binomial nomenclature is a formal system of naming species of living things by giving each a name composed of two parts, both of which use Latin grammatical forms, although they can be based on words from other languages...
of the castor bean tick dates back to the starting point of zoological nomenclature, the 1758 tenth edition of Carl Linnaeus' Systema Naturae
Systema Naturae
The book was one of the major works of the Swedish botanist, zoologist and physician Carolus Linnaeus. The first edition was published in 1735...
, where it appeared as Acarus ricinus. Pierre André Latreille
Pierre André Latreille
Pierre André Latreille was a French zoologist, specialising in arthropods. Having trained as a Roman Catholic priest before the French Revolution, Latreille was imprisoned, and only regained his freedom after recognising a rare species he found in the prison, Necrobia ruficollis...
split the new genus Ixodes
Ixodes
Ixodes is a genus of hard-bodied ticks . It includes important disease vectors of animals and humans . Some ticks in this genus may transmit the pathogenic bacterium Borrelia burgdorferi responsible for causing Lyme disease...
from Linnaeus' Acarus
Acarus
Acarus is a genus of mites in the family Acaridae.-Species:* Acarus ananas * Acarus beschkovi * Acarus bomiensis Wang, 1982* Acarus calcarabellus * Acarus chaetoxysilos Griffiths, 1970...
(which at that time contained all known ticks and mite
Mite
Mites, along with ticks, are small arthropods belonging to the subclass Acari and the class Arachnida. The scientific discipline devoted to the study of ticks and mites is called acarology.-Diversity and systematics:...
s), and I. ricinus was chosen as the type species
Type species
In biological nomenclature, a type species is both a concept and a practical system which is used in the classification and nomenclature of animals and plants. The value of a "type species" lies in the fact that it makes clear what is meant by a particular genus name. A type species is the species...
. It has subsequently been redescribed under a number of junior synonyms and subsequent combinations into different genera; these synonyms include Acarus ricinoides, Cynorhaestes reduvius, Cynorhaestes ricinus, Ixodes megathyreus, Ixodes bipunctatus, Cynorhaestes hermanni, Crotonus ricinus, Ixodes trabeatus, Ixodes plumbeus, Ixodes reduvius, Ixodes pustularum, Ixodes fodiens, Ixodes rufus, Ixodes sulcatus and Ixodes sciuri.