Flea

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Fleas
Temporal range: Early Cretaceous–Recent
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Flea Scanning Electron Micrograph False Color.jpg
False colour scanning electron micrograph of a flea. CDC image.
Scientific classification Red Pencil Icon.png
Kingdom: Animalia
Phylum: Euarthropoda
Class: Insecta
(unranked): Eumetabola
(unranked): Endopterygota
Superorder: Panorpida
Order:Siphonaptera
Latreille, 1825
Suborders

Ceratophyllomorpha
Hystrichopsyllomorpha
Pulicomorpha
Pygiopsyllomorpha

Contents

Synonyms

Aphaniptera

Flea, the common name for the order Siphonaptera, includes 2,500 species of small flightless insects that survive as external parasites of mammals and birds. Fleas live by consuming blood or hematophagy, from their hosts. Adult fleas grow to about 3 mm or .12 in long, are usually brown, and have bodies that are "flattened" sideways, or narrow, enabling them to move through their host's fur or feathers. They lack wings, but have strong claws preventing them from being dislodged; mouthparts adapted for piercing skin and sucking blood, and hind legs extremely well adapted for jumping. They are able to leap a distance of some 50 times their body length, a feat second only to jumps made by another group of insects, the superfamily of froghoppers. Fleas' larvae are worm-like with no limbs; they have chewing mouthparts and feed on organic debris left on their host's skin.

In biological classification, the order is

  1. a taxonomic rank used in the classification of organisms and recognized by the nomenclature codes. Other well-known ranks are life, domain, kingdom, phylum, class, family, genus, and species, with order fitting in between class and family. An immediately higher rank, superorder, may be added directly above order, while suborder would be a lower rank.
  2. a taxonomic unit, a taxon, in that rank. In that case the plural is orders.
Insect class of invertebrates

Insects or Insecta are hexapod invertebrates and the largest group within the arthropod phylum. Definitions and circumscriptions vary; usually, insects comprise a class within the Arthropoda. As used here, the term Insecta is synonymous with Ectognatha. Insects have a chitinous exoskeleton, a three-part body, three pairs of jointed legs, compound eyes and one pair of antennae. Insects are the most diverse group of animals; they include more than a million described species and represent more than half of all known living organisms. The total number of extant species is estimated at between six and ten million; potentially over 90% of the animal life forms on Earth are insects. Insects may be found in nearly all environments, although only a small number of species reside in the oceans, which are dominated by another arthropod group, crustaceans.

Parasitism Interaction between two organisms living together in more or less intimate association in a relationship in which association is disadvantageous or destructive to one of the organisms

In evolutionary biology, parasitism is a relationship between species, where one organism, the parasite, lives on or in another organism, the host, causing it some harm, and is adapted structurally to this way of life. The entomologist E. O. Wilson has characterised parasites as "predators that eat prey in units of less than one". Parasites include protozoans such as the agents of malaria, sleeping sickness, and amoebic dysentery; animals such as hookworms, lice, mosquitoes, and vampire bats; fungi such as honey fungus and the agents of ringworm; and plants such as mistletoe, dodder, and the broomrapes. There are six major parasitic strategies of exploitation of animal hosts, namely parasitic castration, directly transmitted parasitism, trophically transmitted parasitism, vector-transmitted parasitism, parasitoidism, and micropredation.

The Siphonaptera are most closely related to the snow scorpionflies, or snow fleas in the UK, formally the Boreidae, placing them within the Endopterygote insect order Mecoptera. Fleas arose in the early Cretaceous, most likely as ectoparasites of mammals, before moving on to other groups including birds. Each species of flea is more or less a specialist with respect to its host animal species: many species never breed on any other host, though some are less selective. Some families of fleas are exclusive to a single host group; for example, the Malacopsyllidae are found only on armadillos, the Ischnopsyllidae only on bats, and the Chimaeropsyllidae only on elephant shrews.

Mecoptera order of insects

Mecoptera are an order of insects in the superorder Endopterygota with about six hundred species in nine families worldwide. Mecopterans are sometimes called scorpionflies after their largest family, Panorpidae, in which the males have enlarged genitals that look similar to the stingers of scorpions, and long beaklike rostra. The Bittacidae, or hangingflies, are another prominent family and are known for their elaborate mating rituals, in which females choose mates based on the quality of gift prey offered to them by the males. A smaller group is the snow scorpionflies, family Boreidae, adults of which are sometimes seen walking on snowfields. In contrast, the majority of species in the order inhabit moist environments in tropical locations.

The Cretaceous is a geologic period and system that spans 79 million years from the end of the Jurassic Period 145 million years ago (mya) to the beginning of the Paleogene Period 66 mya. It is the last period of the Mesozoic Era, and the longest period of the Phanerozoic Eon. The Cretaceous Period is usually abbreviated K, for its German translation Kreide.

Mammal class of tetrapods

Mammals are vertebrate animals constituting the class Mammalia, and characterized by the presence of mammary glands which in females produce milk for feeding (nursing) their young, a neocortex, fur or hair, and three middle ear bones. These characteristics distinguish them from reptiles and birds, from which they diverged in the late Triassic, 201–227 million years ago. There are around 5,450 species of mammals. The largest orders are the rodents, bats and Soricomorpha. The next three are the Primates, the Cetartiodactyla, and the Carnivora.

The oriental rat flea, Xenopsylla cheopis , is a vector of Yersinia pestis , the bacterium which causes bubonic plague. The disease was spread by rodents such as the black rat, which were bitten by fleas that then infected humans. Major outbreaks included the Plague of Justinian, c. 540 and the Black Death, c. 1350, both of which killed a sizeable fraction of the world's population.

Vector (epidemiology) agent that carries and transmits an infectious pathogen into another living organism

In epidemiology, a disease vector is any agent who carries and transmits an infectious pathogen into another living organism; most agents regarded as vectors are organisms, such as intermediate parasites or microbes, but it could be an inanimate medium of infection such as dust particles.

<i>Yersinia pestis</i> species of bacteria, cause of plague

Yersinia pestis is a gram-negative, nonmotile, rod-shaped coccobacillus bacteria, with no spores. It is a facultative anaerobic organism that can infect humans via the Oriental rat flea. It causes the disease plague, which takes three main forms: pneumonic, septicemic and bubonic plagues. All three forms were responsible for a number of high-mortality epidemics throughout human history, including: the sixth century's Plague of Justinian; the Black Death, which accounted for the death of at least one-third of the European population between 1347 and 1353; and the Third Pandemic, sometimes referred to as the Modern Plague, which began in the late nineteenth century in China and spread by rats on steamboats claiming close to 10,000,000 lives. These plagues likely originated in China and were transmitted west via trade routes. Recent research indicates that the pathogen may have been the cause of what is described as the Neolithic Decline, when European populations declined significantly. This would push the date to much earlier and might be indicative of an origin in Europe rather than Eurasia.

Bubonic plague Human and animal disease

Bubonic plague is one of three types of plague caused by bacterium Yersinia pestis. One to seven days after exposure to the bacteria, flu-like symptoms develop. These symptoms include fever, headaches, and vomiting. Swollen and painful lymph nodes occur in the area closest to where the bacteria entered the skin. Occasionally, the swollen lymph nodes may break open.

Fleas appear in human culture in such diverse forms as flea circuses, poems like John Donne's erotic The Flea , works of music such as by Modest Mussorgsky, and a film by Charlie Chaplin.

Flea circus

A flea circus is a circus sideshow attraction in which fleas are attached to miniature carts and other items, and encouraged to perform circus acts within a small housing.

John Donne 16th and 17th-century English poet and cleric

John Donne was an English poet and cleric in the Church of England.

"The Flea" is an erotic metaphysical poem by John Donne (1572–1631). The exact date of its composition is unknown. The poem uses the conceit of a flea, which has sucked blood from the male speaker and his female lover, to serve as an extended metaphor for the relationship between them. The speaker tries to convince a lady to sleep with him, arguing that if their blood mingling in the flea is innocent, then sexual mingling would also be innocent. His argument hinges on the belief that bodily fluids mix during sexual intercourse.

Morphology and behavior

Fleas are wingless insects, 1/16 to 1/8-inch (1.5 to 3.3 mm) long, that are agile, usually dark colored (for example, the reddish-brown of the cat flea), with a proboscis, or stylet, adapted to feeding by piercing the skin and sucking their host's blood through their epipharynx. Flea legs end in strong claws that are adapted to grasp a host. [1]

Cat flea species of insect

The cat flea is an extremely common parasitic insect whose principal host is the domestic cat, although a high proportion of the fleas found on dogs also belong to this species. This is despite the widespread existence of a separate and well-established "dog" flea, Ctenocephalides canis.

Proboscis an elongated appendage from the head of an animal, either a vertebrate or an invertebrate

A proboscis is an elongated appendage from the head of an animal, either a vertebrate or an invertebrate. In invertebrates, the term usually refers to tubular mouthparts used for feeding and sucking. In vertebrates, a proboscis is an elongated nose or snout.

Unlike other insects, fleas do not possess compound eyes but instead only have simple eyespots with a single biconvex lens; some species lack eyes altogether. [2] Their bodies are laterally compressed, permitting easy movement through the hairs or feathers on the host's body (or in the case of humans, under clothing). The flea body is covered with hard plates called sclerites. [1] These sclerites are covered with many hairs and short spines directed backward, which also assist its movements on the host. The tough body is able to withstand great pressure, likely an adaptation to survive attempts to eliminate them by scratching. [3]

Compound eye Arthropod eye

A compound eye is a visual organ found in arthropods such as insects and crustaceans. It may consist of thousands of ommatidia, which are tiny independent photoreception units that consist of a cornea, lens, and photoreceptor cells which distinguish brightness and color. The image perceived by the arthropod is a combination of inputs from the numerous ommatidia, which are oriented to point in slightly different directions. Compared with single-aperture eyes, compound eyes have poor image resolution; however, they possess a very large view angle and the ability to detect fast movement and, in some cases, the polarization of light.

Adaptation Trait with a current functional role in the life history of an organism maintained and evolved by natural selection

In biology, adaptation has three related meanings. Firstly, it is the dynamic evolutionary process that fits organisms to their environment, enhancing their evolutionary fitness. Secondly, it is a state reached by the population during that process. Thirdly, it is a phenotypic or adaptive trait, with a functional role in each individual organism, that is maintained and has evolved through natural selection.

Fleas lay tiny, white, oval eggs. The larvae are small and pale, have bristles covering their worm-like bodies, lack eyes, and have mouth parts adapted to chewing. The larvae feed on organic matter, especially the feces of mature fleas, which contain dried blood. Adults feed only on fresh blood. [4]

Jumping

Their legs are long, the hind pair well adapted for jumping; a flea can jump vertically up to 7 in (18 cm) and horizontally up to 13 in (33 cm), [5] making the flea one of the best jumpers of all known animals (relative to body size), second only to the froghopper. The flea jump is so rapid and forceful that it exceeds the capabilities of muscle, and instead of relying on direct muscle power, fleas store muscle energy in a pad of the elastic protein named resilin before releasing it rapidly (like a human using a bow and arrow). [6] Immediately before the jump, muscles contract and deform the resilin pad, slowly storing energy which can then be released extremely rapidly to power leg extension for propulsion. [7] To prevent premature release of energy or motions of the leg, the flea employs a "catch mechanism". [7] Early in the jump, the tendon of the primary jumping muscle passes slightly behind the coxa-trochanter joint, generating a torque which holds the joint closed with the leg close to the body. [7] To trigger jumping, another muscle pulls the tendon forward until it passes the joint axis, generating the opposite torque to extend the leg and power the jump by release of stored energy. [7] The actual take off has been shown by high-speed video to be from the tibiae and tarsi rather than from the trochantera (knees). [6]

Life cycle and development

Dog flea (from top) larva, egg, pupa and adult A dog flea (Ctenocephalides canis); adult, pupa, egg and lar Wellcome V0022501EL.jpg
Dog flea (from top) larva, egg, pupa and adult

Fleas are holometabolous insects, going through the four lifecycle stages of egg, larva, pupa, and imago (adult). In most species, neither female nor male fleas are fully mature when they first emerge but must feed on blood before they become capable of reproduction. [3] The first blood meal triggers the maturation of the ovaries in females and the dissolution of the testicular plug in males, and copulation soon follows. [8] Some species breed all year round while others synchronise their activities with their hosts' life cycles or with local environmental factors and climatic conditions. [9] Flea populations consist of roughly 50% eggs, 35% larvae, 10% pupae, and 5% adults. [5]

Egg

The number of eggs laid depends on species, with batch sizes ranging from two to several dozen. The total number of eggs produced in a female's lifetime (fecundity) varies from around one hundred to several thousand. In some species, the flea lives in the nest or burrow and the eggs are deposited on the substrate, [8] but in others, the eggs are laid on the host itself and can easily fall off onto the ground. Because of this, areas where the host rests and sleeps become one of the primary habitats of eggs and developing larvae. The eggs take around two days to two weeks to hatch. [5] Experiments have shown that fleas lay more eggs on hosts which have limited food intakes, and that eggs and larvae survive better under these conditions, perhaps because the host's immune system is compromised. [10]

Larva

Flea larva Flea Larva.jpg
Flea larva

Flea larvae emerge from the eggs to feed on any available organic material such as dead insects, faeces, conspecific eggs, and vegetable matter. In laboratory studies, some dietary diversity seems necessary for proper larval development. Blood-only diets allow only 12% of larvae to mature, whereas blood and yeast or dog chow diets allow almost all larvae to mature. [11] Another study also showed that 90% of larvae matured into adults when the diet included nonviable eggs. [12] They are blind and avoid sunlight, keeping to dark, humid places such as sand or soil, cracks and crevices, under carpets and in bedding. [13]

Pupa

Given an adequate supply of food, larvae pupate and weave silken cocoons after three larval stages. Within the cocoon, the larva moults for a final time and undergoes metamorphosis into the adult form. This can take just four days, but may take much longer under adverse conditions, and there follows a variable-length stage during which the pre-emergent adult awaits a suitable opportunity to emerge. Trigger factors for emergence include vibrations (including sound), heat (in warm-blooded hosts), and increased levels of carbon dioxide, all of which stimuli may indicate the presence of a suitable host. [5] Large numbers of pre-emergent fleas may be present in otherwise flea-free environments, and the introduction of a suitable host may trigger a mass emergence. [13]

Adult

Once the flea reaches adulthood, its primary goal is to find blood and then to reproduce. [14] Female fleas can lay 5000 or more eggs over their life, permitting rapid increase in numbers. [15] Generally speaking, an adult flea only lives for 2 or 3 months. Without a host to provide a blood meal, a flea's life can be as short as a few days. Under ideal conditions of temperature, food supply, and humidity, adult fleas can live for up to a year and a half. [15] Completely developed adult fleas can live for several months without eating, so long as they do not emerge from their puparia. Optimum temperatures for the flea's life cycle are 21 °C to 30 °C (70 °F to 85 °F) and optimum humidity is 70%. [16]

Adult female rabbit fleas, Spilopsyllus cuniculi , can detect the changing levels of cortisol and corticosterone hormones in the rabbit's blood that indicate it is getting close to giving birth. This triggers sexual maturity in the fleas and they start producing eggs. As soon as the baby rabbits are born, the fleas make their way down to them and once on board they start feeding, mating, and laying eggs. After 12 days, the adult fleas make their way back to the mother. They complete this mini-migration every time she gives birth. [16]

Taxonomy and phylogeny

The snow scorpionflies (Boreidae) are the sister clade to the Siphonaptera. Boreus hiemalis2 detail.jpg
The snow scorpionflies (Boreidae) are the sister clade to the Siphonaptera.

Between 1735 and 1758, the Swedish naturalist Carl Linnaeus first classified insects, doing so on the basis of their wing structure. One of the seven orders into which he divided them was "Aptera", meaning wingless, a group in which as well as fleas, he included spiders, woodlice and myriapods. It wasn't until 1810 that the French zoologist Pierre André Latreille reclassified the insects on the basis of their mouthparts as well as their wings, splitting Aptera into Thysanura (silverfish), Anoplura (sucking lice) and Siphonaptera (fleas), at the same time separating off the arachnids and crustaceans into their own subphyla. [17] The group's name, Siphonaptera, is zoological Latin from the Greek siphon (a tube) and aptera (wingless). [18]

Fleas are related to the Diptera (true flies) and the Mecoptera (scorpion flies) as shown in the cladogram, based on a 2008 analysis of four loci (18S and 28S ribosomal DNA, cytochrome oxidase II, and elongation factor 1-alpha) for 128 flea taxa from around the world. The Boreidae (snow scorpionflies) are the sister clade to the Siphonaptera. [19] [20] [21] [22]

part of  Endopterygota
Panorpida
Antliophora

Diptera Common house fly, Musca domestica.jpg

Mecoptera (scorpionflies, hangingflies, 400 spp.) (exc. Boreidae) Gunzesrieder Tal Insekt 3.jpg

Boreidae (snow scorpionflies, 30 spp.) Boreus hiemalis2 detail.jpg

Siphonaptera (fleas, 2500 spp.) Pulex irritans female ZSM.jpg

Amphies.

Trichoptera (caddisflies) Sericostoma.personatum.jpg

Lepidoptera (butterflies and moths) Tyria jacobaeae-lo.jpg

Hymenoptera (sawflies, wasps, ants, bees) AD2009Sep09 Vespula germanica 03.jpg

Amphies. = Amphiesmenoptera
Cenozoic flea in amber, c. 20 mya, is morphologically modern. Flea in amber.jpg
Cenozoic flea in amber, c. 20 mya, is morphologically modern.

Fossils of wingless "pre-fleas" with siphonate (sucking) mouthparts from the middle Jurassic [23] to early Cretaceous have been found in northeastern China. These belonged to three proposed extinct families, the Pseudopulicidae, the Saurophthiridae, and the Tarwiniidae. The last common ancestor of modern Siphonaptera separated from the Mecoptera during the early Cretaceous. Most flea families formed after the end of the Cretaceous (in the Paleogene and onwards). Fleas probably arose in the southern continental area of Gondwana, and migrated rapidly northwards from there. They most likely evolved with mammal hosts, only later moving to birds. [24]

Jigger, Tunga penetrans, in human skin Bicho-de-pe 1.jpg
Jigger, Tunga penetrans , in human skin

Siphonaptera is a relatively small order of insects: members of the order undergo complete metamorphosis and are secondarily wingless (their ancestors had wings which modern forms have lost). In 2005, Medvedev listed 2005 species in 242 genera, and despite subsequent descriptions of new species, bringing the total up to around 2500 species, [19] this is the most complete database available. The order is divided into four infraorders and eighteen families. Some families are exclusive to a single host group; these include the Malacopsyllidae (armadillos), Ischnopsyllidae (bats) and Chimaeropsyllidae (elephant shrews). [25]

Many of the known species are little studied. Some 600 species (a quarter of the total) are known from a single record from a single host. Over 94% of species are associated with mammalian hosts, and only about 3% of species can be considered to be specific parasites of birds. The fleas on birds are thought to have originated from mammalian fleas; at least sixteen separate groups of fleas switched to avian hosts during the evolutionary history of the Siphonaptera. Occurrences of fleas on reptiles is accidental, and fleas have been known to feed on the hemolymph (bloodlike body fluid) of ticks. [25]

Flea phylogeny was long neglected, the discovery of homologies with the parts of other insects being made difficult by their extreme specialization. Whiting and colleagues prepared a detailed molecular phylogeny in 2008, with the basic structure shown in the cladogram. The Tungidae, including the harmful chigoe flea or jigger, is sister to the rest of the Siphonaptera. [19]

Boreidae (snow scorpionflies)

Siphonaptera

Tungidae (inc. chigoe flea or jigger)

Pygiopsyllomorpha

Macropsyllidae, Coptopsyllidae

Neotyphloceratini, Ctenophthalmini, Doratopsyllinae

Stephanocircidae

clade inc. Rhopalopsyllidae, Ctenophthalmidae, Hystrichopsyllidae

Chimaeropsyllidae

Pulicidae (inc. the cat flea, vector of bubonic plague)

Ceratophyllomorpha (inc. the Ceratophyllidae, such as the widespread moorhen flea)

Relationship with host

Fleas feed on a wide variety of warm-blooded vertebrates including humans, dogs, cats, rabbits, squirrels, ferrets, rats, mice and birds. Fleas normally specialise in one host species or group of species, but can often feed but not reproduce on other species. Ceratophyllus gallinae affects poultry as well as wild birds. [26] As well as the degree of relatedness of a potential host to the flea's original host, it has been shown that avian fleas that exploit a range of hosts, only parasitise species with low immune responses. In general, host specificity decreases as the size of the host species decreases. Another factor is the opportunities available to the flea to change host species; this is smaller in colonially nesting birds, where the flea may never encounter another species, than it is in solitary nesting birds. A large, long-lived host provides a stable environment that favours host-specific parasites. [27]

One theory of human hairlessness is that the loss of hair helped humans to reduce their burden of fleas and other ectoparasites. [28]

Direct effects of bites

Human foot infested with jigger fleas, Tunga penetrans Jigger infested foot (2).jpg
Human foot infested with jigger fleas, Tunga penetrans

In many species, fleas are principally a nuisance to their hosts, causing an itching sensation which in turn causes the host to try to remove the pest by biting, pecking or scratching. Fleas are not simply a source of annoyance, however. Flea bites cause a slightly raised, swollen itching spot to form; this has a single puncture point at the centre, like a mosquito bite. [29] :126 Besides this, the eczematous itchy skin disease flea allergy dermatitis is common in many host species, including dogs and cats. [26] The bites often appear in clusters or lines of two bites, and can remain itchy and inflamed for up to several weeks afterwards. Fleas can lead to hair loss as a result of frequent scratching and biting by the animal, and can cause anemia in extreme cases. [29] :126

As a vector

Fleas are vectors for viral, bacterial and rickettsial diseases of humans and other animals, as well as of protozoan and helminth parasites. [30] Bacterial diseases carried by fleas include murine or endemic typhus [29] :124 and bubonic plague. [31] Fleas can transmit Rickettsia typhi , Rickettsia felis , Bartonella henselae , and the myxomatosis virus. [30] :73 They can carry Hymenolepiasis tapeworms [32] and Trypanosome protozoans. [30] :74 The chigoe flea or jigger ( Tunga penetrans ) causes the disease tungiasis, a major public health problem around the world. [33] Fleas that specialize as parasites on specific mammals may use other mammals as hosts; thus, humans may be bitten by cat and dog fleas. [34]

Relationship with humans

In literature and art

Robert Hooke's drawing of a flea in Micrographia, 1665 HookeFlea01.jpg
Robert Hooke's drawing of a flea in Micrographia , 1665

Fleas have appeared in poetry, literature, music and art; these include Robert Hooke's drawing of a flea under the microscope in his pioneering book Micrographia published in 1665, [35] poems by Donne and Jonathan Swift, works of music by Giorgio Federico Ghedini and Modest Mussorgsky, a play by Georges Feydeau, a film by Charlie Chaplin, and paintings by artists such as Giuseppe Crespi, Giovanni Battista Piazzetta, and Georges de La Tour. [36]

Development of the flea from egg to adult. Antonie van Leeuwenhoek, c. 1680 The development of the flea from egg to adult Wellcome M0016633.jpg
Development of the flea from egg to adult. Antonie van Leeuwenhoek, c. 1680

John Donne's erotic metaphysical poem "The Flea", published in 1633 after his death, uses the conceit of a flea, which has sucked blood from the male speaker and his female lover, as an extended metaphor for their sexual relationship. The speaker tries to convince a lady to sleep with him, arguing that if the mingling of their blood in the flea is innocent, then sex would be also. [37]

Flea circuses

A flea circus: "The Go-As-You-Please Race, as seen through a Magnifying Glass", engraved by J. G. Francis, from an article by C. F. Holder in St. Nicholas Magazine, 1886 The Go-As-You-Please Race, as seen through a Magnifying Glass.jpg
A flea circus: "The Go-As-You-Please Race, as seen through a Magnifying Glass", engraved by J. G. Francis, from an article by C. F. Holder in St. Nicholas Magazine, 1886

Flea circuses provided entertainment to nineteenth century audiences. These circuses, extremely popular in Europe from 1830 onwards, featured fleas dressed as humans or towing miniature carts, chariots, rollers or cannon. These devices were originally made by watchmakers or jewellers to show off their skill at miniaturization. A ringmaster called a "professor" accompanied their performance with a rapid circus patter. [38] [39]

Carriers of plague

The Great Plague of London, in 1665, killed up to 100,000 people. Great plague of london-1665.jpg
The Great Plague of London, in 1665, killed up to 100,000 people.

Oriental rat fleas, Xenopsylla cheopis, can carry the coccobacillus Yersinia pestis. The infected fleas feed on rodent vectors of this bacterium, such as the black rat, Rattus rattus, and then infect human populations with the plague, as has happened repeatedly from ancient times, as in the Plague of Justinian in 541–542. [40] Outbreaks killed up to 200 million people across Europe between 1346 and 1671. [41] The Black Death pandemic between 1346 and 1353 likely killed over a third of the population of Europe. [42]

Because fleas carry plague, they have seen service as a biological weapon. During World War II, the Japanese army dropped fleas infested with Y. pestis in China. The bubonic and septicaemic plagues are the most probable form of the plague that would spread as a result of a bioterrorism attack that used fleas as a vector. [43]

The Rothschild Collection

The banker Charles Rothschild devoted much of his time to entomology, creating a large collection of fleas now in the Rothschild Collection at the Natural History Museum, London. He discovered and named the plague vector flea, Xenopsylla cheopis , also known as the oriental rat flea, in 1903. [44] Using what was probably the world's most complete collection of fleas of about 260,000 specimens (representing some 73% of the 2,587 species and subspecies so far described), he described around 500 species and subspecies of Siphonaptera. He was followed in this interest by his daughter Miriam Rothschild, who helped to catalogue his enormous collection of the insects in seven volumes. [45] [46]

Flea treatments

Fleas have a significant economic impact. In America alone, approximately $2.8 billion is spent annually on flea-related veterinary bills and another $1.6 billion annually for flea treatment with pet groomers. Four billion dollars is spent annually for prescription flea treatment and $348 million for flea pest control. [13]

See also

Related Research Articles

Louse order of insects

Louse is the common name for members of the order Phthiraptera, which contains nearly 5,000 species of wingless insect. Lice are obligate parasites, living externally on warm-blooded hosts which include every species of bird and mammal, except for monotremes, pangolins, and bats. Lice are vectors of diseases such as typhus.

Tick order of arachnids

Ticks are small arachnids, typically 3 to 5 mm long, part of the order Parasitiformes. Along with mites, they constitute the subclass Acari. Ticks are ectoparasites, living by feeding on the blood of mammals, birds, and sometimes reptiles and amphibians. Ticks had evolved by the Cretaceous period, the most common form of fossilisation being immersed in amber. Ticks are widely distributed around the world, especially in warm, humid climates.

Parasitoid organism that spends a significant portion of its life history attached to or within a single host organism in a relationship where the host is ultimately killed

A parasitoid is an organism that lives in close association with its host and at the host's expense, and which sooner or later kills it. Parasitoidism is one of six major evolutionary strategies within parasitism, distinguished by the fatal prognosis for the host, which makes the strategy close to predation.

Pterygota subclass of insects

The Pterygota are a subclass of insects that includes the winged insects. It also includes insect orders that are secondarily wingless.

Holometabolism, also called complete metamorphosis, is a form of insect development which includes four life stages: egg, larva, pupa, and imago or adult. Holometabolism is a synapomorphic trait of all insects in the superorder Endopterygota. Immature stages of holometabolous insects are very different from the mature stage. In some species the holometabolous life cycle prevents larvae from competing with adults because they inhabit different ecological niches. The morphology and behavior of each stage are adapted for different activities. For example, larval traits maximize feeding, growth, and development, while adult traits enable dispersal, mating, and egg laying. Some species of holometabolous insects protect and feed their offspring. Other insect developmental strategies include ametabolism and hemimetabolism.

<i>Tunga penetrans</i> species of insect

Tunga penetrans is a parasitic insect found in most tropical and sub-tropical climates. It is native to Central and South America, and has been inadvertently introduced by humans to sub-Saharan Africa.

Snow scorpionfly family of insects

Boreidae, commonly called snow scorpionflies, or in the British Isles, snow fleas are a very small family of scorpionflies, containing only around 30 species, all of which are boreal or high-altitude species in the Northern Hemisphere. Recent research indicates the boreids are more closely related to fleas than to other scorpionflies, which renders the order Mecoptera paraphyletic if the order Siphonaptera is excluded from it.

Oriental rat flea species of insect

The Oriental rat flea, also known as the tropical rat flea, is a parasite of rodents, primarily of the genus Rattus, and is a primary vector for bubonic plague and murine typhus. This occurs when the flea has fed on an infected rodent and bites a human, although this flea can live on any warm blooded mammal.

Medical entomology

The discipline of medical entomology, or public health entomology, and also veterinary entomology is focused upon insects and arthropods that impact human health. Veterinary entomology is included in this category, because many animal diseases can "jump species" and become a human health threat, for example, bovine encephalitis. Medical entomology also includes scientific research on the behavior, ecology, and epidemiology of arthropod disease vectors, and involves a tremendous outreach to the public, including local and state officials and other stake holders in the interest of public safety, finally in current situation related to one health approach mostly health policy makers recommends to widely applicability of medical entomology for disease control efficient and best fit on achieving development goal and to tackle the newly budding zoonotic diseases. Thoughtful to have and acquaint with best practice of Med. Entomologist to tackle the animal and public health issues together with controlling arthropods born diseases by having Medical Entomologists’ the right hand for bringing the healthy world [Yon w].

Human flea species of insect

The human flea – once also called the house flea – is a cosmopolitan flea species that has, in spite of the common name, a wide host spectrum. It is one of six species in the genus Pulex; the other five are all confined to the Nearctic and Neotropical regions. The species is thought to have originated in South America, where its original host may have been the guinea pig or peccary.

Dog flea species of insect

The dog flea is a species of flea that lives as an ectoparasite on a wide variety of mammals, particularly the domestic dog and cat. It closely resembles the cat flea, Ctenocephalides felis, which can live on a wider range of animals and is generally more prevalent worldwide.

Paraneoptera superorder of insects

Paraneoptera is a monophyletic superorder of insects which includes four orders, the bark lice, true lice, thrips, and hemipterans, the true bugs. The mouthparts of the Paraneoptera reflect diverse feeding habits. Basal groups are microbial surface feeders, whereas more advanced groups feed on plant or animal fluids.

<i>Ceratophyllus gallinae</i> species of insect

Ceratophyllus gallinae, known as the hen flea in Europe or the European chicken flea elsewhere, is an ectoparasite of birds. This flea was first described by the German botanist and entomologist Franz von Paula Schrank in 1803.

Pulicidae family of insects

The Pulicidae are a flea family in the order Siphonaptera. Currently, this family has 181 species in 27 genera. Of these, 16 are known from North America.

<i>Hystrichopsylla schefferi</i> species of insect

Hystrichopsylla schefferi, also known as the mountain beaver flea and giant mountain beaver flea, is a parasitic holarctic insect belonging to the order Siphonaptera, the "siphon-wingless" (fleas). With an adult body length of as much as 0.5 inches (13 mm), it is the largest living flea in the world, and is native to the American Northwest. Though most members of the genus Hystrichopsylla are not strongly associated with any particular host animal and will parasitize insectivores and rodents generally, H. schefferi is monoxenously associated with the mountain beaver with which its range is coterminous. The fleas of the family Hystrichopsyllidae, along with the family Pulicidae, are the oldest of fleas in evolutionary history. H. schefferi can be distinguished from the very similar and closely related species Hystrichopsylla gigas dippiei by the number of spines in the pronotal comb, as H. g. dippiei has 36 and H. schefferi has 46.

The hedgehog flea is a flea species which, as indicated by its common name, is an external parasite specifically adapted to living with the European hedgehog and the North African hedgehog, but it has also been found on other animals.

Echidnophaga myrmecobii is a stickfast flea that is native to Australia, and is commonly found on marsupials and rabbits. It is also found on European hares, cats, and dogs.

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