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Xenopsylla cheopisoriental rat flea

By Janki Trivedi

Geographic Range

Xenopsylla cheopis is found worldwide in association with its primary hosts, Rattus spp. (Askew, 1977; Brown, 1975; Busvine, 1966)

Habitat

Xenopsylla cheopis usually inhabits tropical and subtropical habitats, although it has been reported in the temperate zone as well. Xenopsylla cheopis is rarely found in cold areas since it requires a tropical/subtropical climate to pupate. Fleas are prevalent in many major cities. Species of Rattus typically found in city sewer systems and other human related habitats are excellent hosts for X. cheopis. Seaports and other rat-infested areas are also common habitats for X. cheopis.

Fleas are nidiculous parasites; they live in the host's nest. Clothing, beds and couches make perfect homes for many of these fleas. Fleas only attach to the host while they are sucking blood; at other times they are free-living in the host's nest. (Brown, 1975; James and Harwood, 1969)

Physical Description

Adult Xenopsylla cheopis are about 1.5 to 4mm in length and have a laterally compressed body. Like all fleas, X. cheopis adults are wingless. Adults vary from light brown to dark brown in order to camouflage themselves in the host's fur. Adult Xenopsylla cheopis lack both genal and pronotal ctendium (combs of bristles in the front and back). Males and females are sexually dimorphic. Females have dark-colored spermatheca that resemble small sacs, a distinguishing characteristic of this species. Males have complex genitalia that are easily distinguishable from the females'. Larvae are 4.5 mm long and resemble worms; they are slender, white, eyeless, and legless. Each has fourteen bristled segments. During the last larval instar, they molt and form cocoons that are silky and covered in debris from surroundings. (Brown, 1975; James and Harwood, 1969; Rothschild, et al., 1970)

  • Sexual Dimorphism
  • sexes shaped differently
  • Range length
    1.5 to 4 mm
    0.06 to 0.16 in

Development

Fleas are holometabolous, which means they go through four life-cycle stages: egg (embryo), larva, pupa, and adult (imago). Eggs normally incubate for about two to twelve days. Xenopsylla cheopis passes through three molts during the larval stage, which usually lasts about nine to fifteen days, but can last up to 200 days in unfavorable conditions. Next, the larva spins a silk cocoon where it remains until it is finished pupating. During the pupal stage the flea's development rate is greatly affected by its surroundings. Changes in temperature and humidity outside the cocoon can inhibit emerging for up to a full year. (Askew, 1977; Brown, 1975; James and Harwood, 1969)

Reproduction

No information is available on the mating systems of these fleas.

After copulating with a male the female is ready to lay her eggs. She does this at frequent intervals while feeding. Xenopsylla cheopis prefers temperatures of 65 to 80°F with about 70% humidity for egg laying. Higher or lower temperatures inhibit females from laying their eggs. Eggs usually do not hatch on the hosts, rather on their nests since fleas are nidiculous parasites (they live on host's nests). (Askew, 1977; Brown, 1975; James and Harwood, 1969)

  • Breeding season
    These fleas breed year round, as long as the temperature and humidity favor egg-laying.

Xenopsylla cheopis is distinct from other fleas in that it has a very large egg. Studies demonstrate that eggs of X. cheopis obtain extra nutrients from their mother, hence explaining the abnormally large egg. Once eggs are laid, however, they receive no further support from their parents. (Brown, 1975; James and Harwood, 1969)

  • Parental Investment
  • pre-fertilization
    • provisioning
    • protecting
      • female

Lifespan/Longevity

An adult X. cheopis can survive up to 100 days in temperatures of 45 to 50°F. Maximum life span for X. cheopis is 376 days. A long life span increases survival rates of Xenopsylla cheopis, thus resulting in greater a chance of transmitting pathogens. (Brown, 1975; James and Harwood, 1969)

  • Range lifespan
    Status: wild
    376 (high) days

Behavior

The ideal temperature range for X. cheopis is about 65 to 80°F. Xenopsylla cheopis dislikes temperatures much higher than 80°F. Such temperatures are close to human body temperatures, therefore explaining why fleas leave the host when not feeding.

Like other fleas, X. cheopis has very large legs that allow them to jump from one nest to another. An elastic protein called resilin allows fleas to store up energy and then release 97% of it in a single jump. The resilin pad becomes stretched as the flea prepares to jump and the hind femurs retract so that they are almost parallel to the rest of its body. A small catch flips and the legs then lock into place. In order to jump the flea must use its small muscles and unhook the catch, thrusting the flea into a majestic back flip. Fleas cannot control the direction of the jump; they simply land wherever the flip takes them. (Askew, 1977; Rothschild, et al., 1970)

Communication and Perception

Fleas have a pygidium, a sensory organ on their dorsal side, which detects vibrations and air currents. Pupae use these signals to time their emergence from their cocoons. Not much is known about how these fleas communicate with one another. (Askew, 1977)

Food Habits

Adults of both sexes of Xenopsylla cheopis feed on blood. They bite Rattus rattus (Black Rat) and other mammals, including humans. Xenopsylla cheopis obtains the host's blood through a set of external mouthparts, which consist of the following maxillary lacunae and an epipharynx. The purpose of each structure is to aid in the sucking up of blood. After biting, the fleas suck blood from a pool (telmophagy), unlike some other insects like mosquitoes that feed directly from the blood vessel (solenophagy).

Piercing of the host's skin is achieved by the back and fourth action of the maxillary laciniae. After the skin is cut the epipharynx enters the wound and injects salvia. Saliva contains special chemicals, which keep the host's blood from coagulating. A canal formed by the maxillary laciniae and the epipharnyx then sucks up blood. Further down the gut a specialized organ called the proventriclus then breaks down blood cells enabling the X. cheopis to digest the blood meal. The average capacity of Xenopsylla cheopis is 0.5 cubic millimeters.

The larvae of X. cheopis have mandibles, which they use to feed on detritus and the feces of the adult fleas, which are found in the nests of hosts. (Beaver, et al., 1984; James and Harwood, 1969; Rothschild, et al., 1970)

  • Animal Foods
  • blood

Ecosystem Roles

Xenopsylla cheopis is a parasite of many mammalian species, including Rattus and humans. Because of its parasitic nature, Xenopsylla cheopis is a vector for pathogens such as plague bacilli, Yersina pestis, and murine typhus, Rickettsia typhi. Transmission of the pathogen occurs as bacteria enter the flea's gut and multiply rapidly. Soon the flea's proventriculus is blocked by a mass of bacteria and it cannot fill its stomach, causing the flea to search for a new host. After biting the host, the blood of an uninfected host mixes with bacteria in the flea's stomach; the flea expels infected blood back into the wound consequently, infecting a new host. Xenopsylla cheopis goes from host to host infecting the uninfected. Hosts may also become infected either from consuming fecal matter or dead remnants of an infected X. cheopis.

Xenopsylla cheopis carries the tapeworm of rats and mice, Hymenolepis diminut (rat tapeworm) and serves as an intermediate host for Hymenolepis nana (mouse tapeworm). (Beaty and Marquardt, 1996; Beaver, et al., 1984; Brown, 1975; James and Harwood, 1969)

Species Used as Host

Economic Importance for Humans: Negative

Besides just being pesky when it bites, Xenopsylla cheopis is a vector of plague bacilli, Yersina pestis, and the agent of murine typhus, Rickettsia typhi. Both diseases are a threat to humans and other animals that encounter them. In urban foci, the reservoir hosts of plague are usually species of Rattus, most commonly Rattus rattus. (Beaty and Marquardt, 1996; Beaver, et al., 1984; Brown, 1975; James and Harwood, 1969)

  • Negative Impacts
  • injures humans
    • carries human disease
  • household pest

Conservation Status

Xenopsylla cheopis is quite common throughout the world. (James and Harwood, 1969)

  • IUCN Red List [Link]
    Not Evaluated

Other Comments

A study done in 1997 demonstrates that X. cheopis has evolved resistance to commercial insect repellents due to its long association with humans. (Rutledge, et al., 1997)

Contributors

Allison Poor (editor), University of Michigan-Ann Arbor.

Janki Trivedi (author), University of Michigan-Ann Arbor, Teresa Friedrich (editor), University of Michigan-Ann Arbor.

Glossary

agricultural

living in landscapes dominated by human agriculture.

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.

carnivore

an animal that mainly eats meat

chaparral

Found in coastal areas between 30 and 40 degrees latitude, in areas with a Mediterranean climate. Vegetation is dominated by stands of dense, spiny shrubs with tough (hard or waxy) evergreen leaves. May be maintained by periodic fire. In South America it includes the scrub ecotone between forest and paramo.

cosmopolitan

having a worldwide distribution. Found on all continents (except maybe Antarctica) and in all biogeographic provinces; or in all the major oceans (Atlantic, Indian, and Pacific.

desert or dunes

in deserts low (less than 30 cm per year) and unpredictable rainfall results in landscapes dominated by plants and animals adapted to aridity. Vegetation is typically sparse, though spectacular blooms may occur following rain. Deserts can be cold or warm and daily temperates typically fluctuate. In dune areas vegetation is also sparse and conditions are dry. This is because sand does not hold water well so little is available to plants. In dunes near seas and oceans this is compounded by the influence of salt in the air and soil. Salt limits the ability of plants to take up water through their roots.

detritus

particles of organic material from dead and decomposing organisms. Detritus is the result of the activity of decomposers (organisms that decompose organic material).

ectothermic

animals which must use heat acquired from the environment and behavioral adaptations to regulate body temperature

fertilization

union of egg and spermatozoan

forest

forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.

internal fertilization

fertilization takes place within the female's body

iteroparous

offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).

metamorphosis

A large change in the shape or structure of an animal that happens as the animal grows. In insects, "incomplete metamorphosis" is when young animals are similar to adults and change gradually into the adult form, and "complete metamorphosis" is when there is a profound change between larval and adult forms. Butterflies have complete metamorphosis, grasshoppers have incomplete metamorphosis.

motile

having the capacity to move from one place to another.

mountains

This terrestrial biome includes summits of high mountains, either without vegetation or covered by low, tundra-like vegetation.

oviparous

reproduction in which eggs are released by the female; development of offspring occurs outside the mother's body.

parasite

an organism that obtains nutrients from other organisms in a harmful way that doesn't cause immediate death

rainforest

rainforests, both temperate and tropical, are dominated by trees often forming a closed canopy with little light reaching the ground. Epiphytes and climbing plants are also abundant. Precipitation is typically not limiting, but may be somewhat seasonal.

saltatorial

specialized for leaping or bounding locomotion; jumps or hops.

sanguivore

an animal that mainly eats blood

scrub forest

scrub forests develop in areas that experience dry seasons.

sexual

reproduction that includes combining the genetic contribution of two individuals, a male and a female

suburban

living in residential areas on the outskirts of large cities or towns.

tactile

uses touch to communicate

temperate

that region of the Earth between 23.5 degrees North and 60 degrees North (between the Tropic of Cancer and the Arctic Circle) and between 23.5 degrees South and 60 degrees South (between the Tropic of Capricorn and the Antarctic Circle).

terrestrial

Living on the ground.

tropical

the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.

tropical savanna and grassland

A terrestrial biome. Savannas are grasslands with scattered individual trees that do not form a closed canopy. Extensive savannas are found in parts of subtropical and tropical Africa and South America, and in Australia.

savanna

A grassland with scattered trees or scattered clumps of trees, a type of community intermediate between grassland and forest. See also Tropical savanna and grassland biome.

temperate grassland

A terrestrial biome found in temperate latitudes (>23.5° N or S latitude). Vegetation is made up mostly of grasses, the height and species diversity of which depend largely on the amount of moisture available. Fire and grazing are important in the long-term maintenance of grasslands.

urban

living in cities and large towns, landscapes dominated by human structures and activity.

vibrations

movements of a hard surface that are produced by animals as signals to others

year-round breeding

breeding takes place throughout the year

References

Askew, R. 1977. Parasitic Insects. Pp. 559 in G Schmidt, L Roberts, eds. Foundations of Parasitology. Saint Louis: McGraw Hill Company.

Beaty, B., W. Marquardt. 1996. The Biology of Disease Vectors. Niwot: University Press of Colorado.

Beaver, P., R. Jung, E. Cupp. 1984. Clinical Parasitology. Philadelphia: Lea & Febiger.

Brown, H. 1975. Basic Clinical Parasitology. New York: Appleton-Century Crofts.

Busvine, J. 1966. Insects and Hygiene. London: Methuen & Co..

James, M., R. Harwood. 1969. Herms's Medical Entomology. New York: Macmillan Publishing Co..

O'Toole, C. 1989. The Encyclopedia of Insects. New York: Facts on File Inc.

Rothschild, M., B. Ford, M. Hughes. 1970. Maturation of the male rabbit flea (*Spilopsyllus cuniculi*) and the Oriental rat flea (*Xenopsylla cheopis*): Some effect of mammalian hormones on development and impregnation.. Pp. 559-561 in G Schmidt, L Roberts, eds. Foundations of Parasitology. McGraw Hill Companies.

Rutledge, L., R. Gupta, Z. Mehr. 1997. Evolution of repellent tolerances in representative arthropods. Journal of American Mosquito Control Association, 13: 329-334.

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