Pests, Plagues & Politics Pests, Plagues & Politics Lecture 7Lecture 7

BUGS ON YOUBUGS ON YOU

Key PointsBugs Living on You

• Historical Perspective

• Obligate Parasites– 3 Types of Lice– Biology and control

• Facultative Parasites– Human Flea, Bot Fly, Sand Fleas– Bed Bugs

Bugs On YouBugs On You

Demodex follicularumDemodex follicularumthe human follicle mitethe human follicle mite

BUGS ON YOUBUGS ON YOU

““Even a superficial survey of the evolution of Even a superficial survey of the evolution of human cleanliness reveals that its developmenthuman cleanliness reveals that its developmenthas lagged far behind the intellectual, aesthetic,has lagged far behind the intellectual, aesthetic,and moral progress of man.and moral progress of man.Cleanliness has not been akin to godliness.Cleanliness has not been akin to godliness.””

H. Zinsser, RATS, LICE & HISTORY

Bugs On YouBugs On You

• Saint Benedict (6th century)– “Bathing shall seldom be permitted.”

• Saint Francis of Assisi– “an unwashed body is the stinking badge of piety.”

• Queen Isabelle of Castile– boasted of two baths in her life

• Napoleon, in a letter to Josephine– “Be home in two weeks. Don’t bathe.”

Bugs On YouBugs On You

• Colonial America– Pennsylvania & Virginia

• laws which either banned or limited bathing– Philadelphia

• bathing more than one a month prohibited

• Why??– Bathing meant nudity which could only

promote promiscuity

The Strongest BondThe Strongest BondThe Strongest BondThe Strongest Bond

Bugs On YouBugs On You

• OBLIGATEOBLIGATE Insect Parasites of Humans– parasitism (Gr. ParasitosParasitos = eating with another)

• LICELICE– Order Anoplura (“unarmed tail”)– The Sucking LiceSucking Lice

• parasitic on mammals & birds • 15 families & ca. 500 species worldwide

– HaemophagicHaemophagic with piercing/sucking mouthparts.– WinglessWingless with flattened bodies– HemimetabolousHemimetabolous (incomplete metamorphosis)

Human LiceHuman Lice

• Three “types” - Two species– Pediculus humanus capitus

• The Head Louse– Pediculus humanus humanus

• The Body Louse– Pthirus pubis

• The Crab Louse

Head LiceHead Lice• Pre-WWI: head lice a familiar feature in American homes.

• Now making a come back

– est. 12,000,000 cases in the U.S.

• Female Louse

– 50 to 150 eggs (egg = NIT) in her life time

– lays them at the base of hairs

– eggs hatch in 5 to 10 days - three molts

– three weeks “egg to egg”

Louse egg on a human hairThe NIT

Louse about to hatch from the egg.

Adult louse

Head lice (Pediculus humanus capitis) are tiny insects about two millimeters long which live on the scalp and neck of humans.

First The BiologyFirst The Biology

They feed from human blood and must eat at least twice a day; they cannot survive for more than one day at room temperature off a human body.

Head LiceHead Lice

• Transmission– close physical contact– exchange of combs &/or hats

• Slang– WWI & II

• “motorized dandruff”

Common Chemical TreatmentsCommon Chemical Treatments

•Nix•Rid•Pronto•Clear

One other problem…One other problem…

• RESISTANCE:– Overuse of pediculicidal products

has lead to decreased effectiveness

– These survivors are breeding a new super race of lice, resistant to our chemicals

• SAFER ALTERNATIVES:

Head Lice to Dead Lice– Incorporates a“5 step battle plan”– Promotes use of olive oil to kill resistant adult lice

PART 1 - http://www.youtube.com/watch?v=UCoZP5Aso5UPART 2 - http://www.youtube.com/watch?v=UCoZP5Aso5U

Body LouseBody Louse

• P.h. humanus– Latin: Pedis - louse; Pediculus = small louse– English: Pedicular, an adj. = lousy

• “A dozen white louses do become an old coat well; It’s a familiar beat to man and signifies love.”

Wm. Shakespeare; Merry Wives of Windsor

Body LouseBody Louse• Normally found on clothing• Louse is on you only during feeding

– usually when you’re sleeping

• Spends most of time in the seams of your clothing (ergo common name “seam squirrel”)

• Eggs deposited on clothing• Transmitted via exchanged clothing• Average # lice per host = dozen• A known vector of typhus

Body LouseBody Louse

• Control– Allogrooming– vignette: Richard the Lion Hearted & his

‘permitted’ washer women– Chemical

• DDT saved millions

– The Whirlpool washing machine and a dramatic increase in personal hygiene.

Lice tell us when humans began to Lice tell us when humans began to wear clothes!!!wear clothes!!!

• Recent molecular DNA studies of head lice & body lice show:– Body lice diverged from head lice about

72,000 42,000 years ago– Body lice live in the clothing– Ergo humans ran around naked for longer

than we thought.– Study also supports African origin for

Homo.

Crab LouseCrab Louse

• Also known as the pubic louse (& other nomens)• Infests the pubic regions

– requires well spaced hair– stationary beast & spends long amounts of time

feeding (quite irritating) – up to 30 eggs per female louse

Crab LouseCrab Louse

• Transmission– Venereal (from Venus, Roman Goddess of Love) – an

STD

• Frequency– OSU Student Health Center

• 2.4% of student population

• Only one other species in the genus– Pthirus gorillae

Facultative Parasites of HumansFacultative Parasites of Humans

• These are parasites that normally These are parasites that normally utilize non-human hosts, but can use utilize non-human hosts, but can use humans as an alternative.humans as an alternative.

The The ““HumanHuman”” Flea Flea

• Numerous species of fleas will feed on human blood.– Cat flea

– Dog flea

– Ground squirrel flea (which is a known vector of plague)

• Human flea: Pulex irritans– cosmopolitan & normally a parasite of swine

The “Human” Flea

• “It was often said that women were attacked by fleas more often than men were. The cause may conceivable have been a response to ovarian hormones.”– Miriam Rothschild, Scientific American (1965)

Human Bot FlyHuman Bot Fly

• Order Diptera

• Dermatobia hominus– South & Central American distribution– Female fly lays her eggs on mosquito &

other “bugs”– Mosquito bites human

• fly larvae “pop” out of eggs and penetrate human

• develop within the human and bore out to pupate

Human Bot FlyHuman Bot Fly

• Also known as the “torsalo”• 3 - 4 weeks in the larval stage undergoing

three instars

Sand FleaSand Flea• A true flea (Order SiphonapteraSiphonaptera)

– family Tungidae– Tunga penetrans

• New World tropical & sub-tropical

• Common names– jigger - chigger - chigoe

• Minute: 1 mm in length

• Female borrows into skin & feeds & grows

• Larval fleas crawl out of host & spend their pupal phase in the ground/soil/sand

Sand FleasSand Fleas&&

YouYou

Sand fleas are well known to Sand fleas are well known to human civilizations.human civilizations.

Chimu (pre-Incan) pottery from Peru depicting feet with punch holes, a result of sand flea infestation.

Bed BugsBed Bugs

• Order Hemiptera– Cimex lectularius– Haematophagous - a blood meal between each

molt– Closest relative is the BAT bed bug

• a’ha, where were we living 30,000 years ago??

“Night-night, dear, sleep tight…and don’t let the bedbugs bite.”

Corvallis G.T. – 28 November 2003

Key PointsBugs Living on You

• Historical Perspective

• Obligate Parasites– 3 Types of Lice– Biology and control

• Facultative Parasites– Human Flea, Bot Fly, Sand Fleas– Bed Bugs