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Cimex hemipterustropical bedbug

By Daniel Fargo

Geographic Range

Cimex hemipterus is limited to tropical regions between thirty degrees north and south of the equator. (Usinger, 1966)

Habitat

Like all bedbugs, tropical bedbugs are nidicolous parasites, living in the same environment as their hosts and feeding off of the host at night. Bedbugs are adverse to light and as such, hide in very small crevices during daylight. Cimex hemipterus prefers materials such as wood and paper over stone, plaster, or textiles for refuges. (Roberts and Janovy, 2000; Usinger, 1966)

Physical Description

Adult Cimex hemipterus are reddish-brown and can reach up to eight millimeters in length. They are flattened dorsoventrally and lack wings. Antennae are comprised of four segments with the distal two segments covered in sensilla for enhanced sensory perception. These sensory hairs are also abundant on the legs, thorax, and abdomen. Bedbugs have compound eyes and a heavily sclerotized pronotum (just after the head, on the first thoracic somite or body segment) twice as broad as it is long. Cimex hemipterus also have legs that are not particularly adept at clinging, but rather allow for rapid movement over the host's body. On the ventral side of the third thoracic somite is a pair of scent glands. These glands produce an oily secretion that is thought to be a defense mechanism against predators. Females are negligibly longer and wider than males, although their sensory bristles are somewhat shorter. (Roberts and Janovy, 2000; Singh, et al., 1996)

  • Sexual Dimorphism
  • female larger
  • Range length
    8 (high) mm
    0.31 (high) in

Development

Eggs hatch in roughly ten days and larvae pass through a series of five instars before reaching adulthood. Each instar requires a blood meal and corresponds to an increase in weight by a factor of 2.5 to 5. It can take 37 to 128 days for an egg to reach maturity at high temperatures. A once-fed bedbug will mature ten times faster at 37° C then at 10° C. For example, C. hemipterus will pass through its second instar in 19.7 days at 37 degrees compared to 197 days at 10 degrees. Starvation however, will further increase the instar periods. (Newberry, 1989; Roberts and Janovy, 2000; Usinger, 1966)

Reproduction

Bedbugs have a rare mating method known as traumatic insemination. The male has a small aedeagus, or penis, that lies at the base of an appendage called the paramere which curves out to the left. The paramere inserts into a notch known as the paragenital sinus on the right side of the female's fifth abdominal segment. The male then releases sperm into a "pocket" known as the spermalege upon which the sperm make their way through the hemocoel to the seminal conceptacles (organs located at the base of the oviducts). The sperm then travel through the walls of the oviducts where they can fertilize the eggs. Cimex hemipterus males require a blood meal before copulating and females require a blood meal before they oviposit. As a side note, males will mate with females repeatedly, and it is not uncommon for a male to exhibit homosexual behavior. (Newberry, 1989; Roberts and Janovy, 2000; Usinger, 1966)

Females will oviposit anywhere from 200 to 500 eggs in clusters of twenty to fifty. Bedbugs are very adverse to light and as such, hide in very small crevices during daylight. Cimex hemipterus prefers spaces built with materials such as wood and paper to stone, plaster, or textiles. Large clusters of bedbugs called "brood centers" will develop on a preferred substrate. The biggest factor needed for the success of a brood center however, is that it is dry, rough, and dark. These brood centers can be found near the beds of humans, in chicken roosts, or in caves. (Newberry, 1989; Roberts and Janovy, 2000; Usinger, 1966)

  • Range eggs per season
    200 to 500

Behavior

Cimex hemipterus are nocturnal with peak activity being just before dawn. Bedbugs emerge from their daytime hiding spaces and locate their host by following a temperature gradient and possibly a carbon dioxide gradient as well. (Roberts and Janovy, 2000; Usinger, 1966)

Communication and Perception

Food Habits

Cimex hemipterus are solenophages, meaning that they feed by piercing blood vessels and drawing up the fluids. A fascicle containing the mandibles and maxillae penetrates the hosts skin until a blood vessel is reached. This vessel is then penetrated and blood is drawn up through the fascicle to the gut. During this process, the labium bends and folds to support the fascicle allowing for maximum penetration. The saliva of C. hemipterus contains a variety of anticoagulants to keep the wound from clotting during feeding. Cimex hemipterus ancestrally parasitized bats. When early man lived in the caves however, bedbugs made the jump to humans who are now the principle host for these insects. Chickens may also serve as hosts for bedbugs.

Cimex hemipterus can survive long periods of starvation. Adults routinely live through periods of four months without food and a survival period in excess of eighteen months without food has been reported.

Males and females differ in relation to the size of their blood meals. Comparison of females and males of similar body weights showed females taking blood meals nearly double the size of blood meals by males. Also, testing of blood meals among individuals in their fifth instar showed similar results for individuals that went on to become females compared to those that became males upon maturity. This difference is most likely due to the higher metabolic strain on females who produce energetically costly eggs as opposed to males who produce very low-energy sperm. (Roberts and Janovy, 2000; Yanovski and Ogston, 1982)

  • Animal Foods
  • blood

Predation

Economic Importance for Humans: Negative

Though it is not a vector of serious diseases, C. hemipterus still causes problems for its human hosts. People often have allergic reactions or periods of irritation from bedbug bites. Areas infested with C. hemipterus tend to have a foul odor as well as spotting on furniture and walls due to the bedbug's oily secretions. People can also lose sleep due to entomophobia, the fear of "bugs." (Usinger, 1966; Vall Meyers, et al., 1994; Webb, et al., 1989)

  • Negative Impacts
  • injures humans
    • bites or stings
  • household pest

Conservation Status

Tropical bedbug populations are in no danger of diminishing.

Other Comments

Cimex hemipterus males will often interbreed with females of the closely related species Cimex lectularius resulting in sterile eggs. A study in Kwa-Zulu, South Africa showed that a correlation exists between the percentage of C. hemipterus in the population and the propensity for females of C. lectularius to lay sterile eggs. When C. hemipterus accounted for more than 75% of the population, most of the C. lectularius females lay only sterile eggs (Newberry, 1989; Roberts and Janovy, 2000; Usinger, 1966)

Contributors

Sara Diamond (editor), Animal Diversity Web.

Daniel Fargo (author), University of Michigan-Ann Arbor, Teresa Friedrich (editor), University of Michigan-Ann Arbor.

Glossary

Ethiopian

living in sub-Saharan Africa (south of 30 degrees north) and Madagascar.

World Map

Neotropical

living in the southern part of the New World. In other words, Central and South America.

World Map

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

chemical

uses smells or other chemicals to communicate

ectothermic

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

fertilization

union of egg and spermatozoan

heterothermic

having a body temperature that fluctuates with that of the immediate environment; having no mechanism or a poorly developed mechanism for regulating internal body temperature.

infrared/heat

(as keyword in perception channel section) This animal has a special ability to detect heat from other organisms in its environment.

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.

native range

the area in which the animal is naturally found, the region in which it is endemic.

nocturnal

active during the night

oviparous

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

polygynandrous

the kind of polygamy in which a female pairs with several males, each of which also pairs with several different females.

sanguivore

an animal that mainly eats blood

suburban

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

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.

urban

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

References

Newberry, K. 1989. The effects on domestic infestations of Cimex lectularius bedbugs of interspecific mating with C. hemipterus. Medical and Veterinary Entomology, 3: 407-414.

Roberts, L., J. Janovy. 2000. Gerald D. Schmidt and Larry S. Roberts’ foundations of parasitology (Sixth Ed.). Boston, MA: McGraw-Hill.

Singh, R., K. Singh, S. Prakash, M. Mendki, K. Rao. 1996. Sensory organs on the body parts of the bed-bug Cimex hemipterus Fabricus and the anatomy of its central nervous system. International Journal of Insect Morphology and Embryology, 25: 183-204.

Usinger, R. 1966. Monograph of Cimicidae. College Park, MD: Entomological Society of America.

Vall Meyers, M., A. Hall, H. Inskip, S. Lindsay, J. Chotard. 1994. Do bedbugs transmit hepatitis B?. Lancet, 343: 761-763.

Webb, P., C. Happ, G. Maupin, B. Johnson, C. Ou. 1989. Potential for Insect Transmission of HIV: Experimental Exposure of Cimex hemipterus and Toxorhynchites amboinensis to Human Immunodeficiency Virus. The Journal of Infectious Diseases, 160: 970-977.

Yanovski, A., C. Ogston. 1982. Sex differences in size of the blood meal in the bed bug Cimex hemipterus. Journal of Medical Entomology, 19: 45-47.

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