The Biology Behind Bed Bugs - Region of Peel · • Evolutionary adaptations of bed bugs closely tied to human evolution and behavior • There are multiple causes to bed bug resurgence

The Biology Behind Bed BugsMark P Nelder

Public Health Incident Response

Volker Steger/Science Photo LibraryVolker Steger/Science Photo Library

Outline

• Purpose

• History of Bed Bugs

• The Resurgence

• Clinical Consequences

• Bionomics

• Conclusions

• Selected References

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Richard Naylor/University of Sheffield

Purpose

• Outline aspects of bed bug biology and evolution that have contributed to their success

• Provide scientific background, so you are better able to respond to an ever-increasing public concern

• Provide updates on latest science into the biology of bed bugs

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History

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Evolution and Transport

• Paleolithic Era (2.6 million to 10,000 yrs ago)• Caves of Middle East and Mediterranean

• Cave dwelling bats

• Agricultural Revolution (10,000-7,000 yrs ago)• Humans moving to towns and villages

• Transported cave pests with them

• Ancient Egypt (3,550 yrs ago)• Bed bugs in tombs

• Ancient Rome and Greece (2,400 yrs ago) • Bed bugs well represented in early writings

• Early Colonists to North America (400 yrs ago)• Carried bed bugs to New World

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Early 20th Century Toronto

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• Context

1905

1915

1925

1926

The Resurgence

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Resurgence Hypotheses

• Lack of public awareness

• Reintroduction via growth of international travel and trade

• Bed bug resistance to insecticides

• Changes in pest management practices; a shift away from

broad spectrum pesticides to pest-specific bait products

• Now fashionable to buy second-hand items

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Google Trends

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Insecticide Resistance

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US Army Environmental Hygiene Division. 1962. Insecticide resistance of medically important arthropods.

Insecticide Resistance

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Population Genetics

• Coby Schal Lab, NC State University, studying population genetics of

US Atlantic coast populations.

• What is source of recent emergence in North America: 1) native

urban reservoirs, 2) local poultry farms, and 3) invasion through

international travel?

• Within populations: Very low genetic diversity and high inbreeding;

populations appear to be founded by a singly mated female

• Across populations: Very high genetic diversity and high genetic

differentiation; multiple introductions; human-mediated transport

• Source: Schal, C. 2011. Importance of Basic and Translational Approaches in Bed Bug Research. EPA

Bed Bug Summit, February 1-2. Presentation Link

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Clinical Consequences

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Bite Appearance• Bed bug bites often resemble and can be

mistaken for other insect bites, a number of

skin conditions, or chicken pox.

• Bites are usually painless, despite leaving small,

visible puncture marks on the skin, and most

people do not report a reaction.

• The development of 2-5-mm itchy, red, raised

or flat bumps are the most common reactions

seen.

• Most bites will heal within a week, unless they

are aggravated by scratching.

• Individuals exposed to repeated bites can also

develop allergic reactions to the bed bugs’

saliva, which resemble allergic reactions to

insect stings.

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Stucki, A and R Ludwig. 2008. Bed bug bites. N Engl J Med 359:1047.

Difficulty in Diagnoses

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Treatment

• While rare, body-wide reactions can occur and usually present as widespread itching and rashes.

• Currently there is no evidence that bed bugs transmit blood-borne infectious agents, e.g., Hepatitis B, Hep C, or HIV.

• Bed bug bites do not usually require any medical treatment.

• Creams with corticosteroids and oral antihistamines may be advised in more severe cases.

• Local antiseptic lotion or antibiotic cream can be applied if secondary infection occurs.

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Delaunay, P et al. 2011. Bedbugs and infectious disease. CID 52:200-210.

MRSA (Defining What is a Vector)

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Bionomics

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Identification

• Blood-feeding, flightless, oval, flattened insects

• Life cycle contains eggs, nymphs, and adults

• Adults are reddish-brown and 6 mm long

• Nymphs look like adults, but smaller, lighter colour

• Eggs are 1 mm in diameter, whitish/cream colour

Identifying pest correctly is key to successful management

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Identification: Bed Bug Relatives

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Wikipedia Bugguide.netN Gallagher/Ohio State Univ

Reproduction

• Bed bugs possess a unique mode of copulation (i.e. traumatic insemination)

• Male’s genitalia pierces the female's abdominal wall, inseminating her body cavity

• Nymphs emit pheromones to signal reproductive immaturity

• Female hides after mating

• Semiochemicals (behaviour and physiology-modifying chemicals) that can be exploited

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Chemical Communication

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Chemical Communication

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Development

• Egg-Nymph-Adult

• Will feed on pets such as dogs or cats when humans not available

• Prefer temperatures from 21-27°C

• A female will lay eggs singly, up to 5-7 per day and up to 500 in her lifetime

• Egg to adult development time: @18°C = 180 days; @33°C = 37 days

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Life Cycle

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J Austin/Texas A&M

Host Seeking

• Bed bugs can travel up to 6

meters in search of human

host

• Are attracted to human

host’s carbon dioxide, heat,

and chemical cues

• Olfaction through antennae

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Host Seeking

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Smelling Organs of the Antenna

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Blood Feeding

• Blood feed chiefly at night

• Both sexes blood feed, no other source of nutrition

• Inject saliva containing anticoagulants (keeps blood flowing) and anaesthetics (so people do not feel bite and interrupt feeding)

• Feed for 10-20 minutes and return to hiding places

• Feed on exposed areas of skin such as arms and neck

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Dennis Kunkel Microscopy/Corbis

Natural Enemies

• Cockroaches

• Assassin bugs

• Ants

• Trypanosomes (protozoa)

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Endosymbionts

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Habitat

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• Blood feed chiefly at night



Habitat

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Conclusions

• Evolutionary adaptations of bed bugs closely tied to human evolution and behavior

• There are multiple causes to bed bug resurgence

• Use the bed bug’s own biology against them – pheromones, endosymbionts

• Science of bed bug biology was lost soon after invention of DDT, but is now growing quickly

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Selected References

• Bai X, et al. 2011. Transcriptomics of the bed bug (Cimex lectularius). PLoS ONE

6(1):e16336. Article

• Christoph Liedtke H, et al. 2011. Alarm pheromones and chemical communication

in nymphs of the tropical bed bug Cimex hemipterus (Hemiptera: Cimicidae). PLoS

ONE 6(3):e18156. Article

• Harraca V, et al. 2010. Nymphs of the common bed bug (Cimex lectularius) produce

anti-aphrodisiac defence against conspecific males. BMC Biology 8:121. Article

• Harraca V, et al. 2010. Characterization of the antennal olfactory system of the bed

bug (Cimex lectularius). Chem Senses 35:195-204. Article

• Lowe CF, and MG Romney. 2011. Bedbugs as vectors for drug-resistant bacteria.

Emerg Infect Dis 17:1132-4. Article

• Hosokawa T, et al. Wolbachia as a bacteriocyte-associated nutritional mutualist.

PNAS 107:769-774. Article

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Acknowledgements

• Lisa Fortuna

• Doug Sider

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Documents

The Biology Behind Bed Bugs - Region of Peel · • Evolutionary adaptations of bed bugs closely tied to human evolution and behavior • There are multiple causes to bed bug resurgence