Class Insecta

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Class Insecta
Class Insecta is the largest class of animals.
Characteristics 1. 3 body parts -
________________________________ 2.
_______________________________ contains pair of
compound eyes, ocelli, and 1 pair of antennae. 3.
____________________________ possesses 3
segments, each with a pair of legs. Wings may
or may not be present extend from last 2
segments if present.
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Characteristics cont 4. Abdomen contains
________________________________ - insects are
___________________________________ 5. Possess 2
types of metamorphosis a.
________________________ egg nymph
adult b. ________________________egg
larva pupa adult Cla
ss Insecta contains some 26 orders, 4 of which
are important in parasitology.
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Insects with Incomplete Metamorphosis
ORDER PHTHIRAPTERA LICE (Chap. 36) 2 groups
Chewing Lice and Sucking Lice Chewing Lice
(formerly in Order Mallophaga) ___________________
_________________ Ectoparasites of birds and
mammals - feed on ________________________________
_______ None infest humans.
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Insects with Incomplete Metamorphosis
One chewing louse of importance Trichodectes
canis - ______________________
_________________________________________ Charact
eristics wingless head is wider than thorax
tiny 1st pair of legs - heavy infestations can
cause hair loss in puppies - intermediate host of
______________________ __________________________
_____________  
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Sucking lice (formerly in the Order
Anoplura) Mouthparts modified to suck blood of
their host. Head is narrower than
thorax. Ectoparasites of mammals only. 2 species
occur on humans some veterinary species
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Pediculus humanus
Human head and body lice. Also known as
"cooties", graybacks, and mechanized
dandruff". 2 subspecies Pediculus humanus
humanus - Pediculus humanus capitis -  
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Pediculus humanus
Morphology Adult is 2-3 mm in length. Body is
dorsoventrally flattened with head narrower than
thorax. 3 pairs of legs are similar. Male is
recognized by posterior copulatory structure
called the _____________________
MALE
FEMALE
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Life Cycle of Pediculus humanus
Incomplete metamorphosis egg ( nit)
nymph adult Female cements nits to
clothing fibers or hairs. Eggs hatch
into nymphs (immature adults). Nymphs
undergo 3 molts and become adults in 8-9 days.
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Life Cycle of Pediculus humanus
TRANSMISSION of lice from person to person is
associated with crowding of infested people (i.e.
prisons, institutions, schools, etc.) -
Outbreaks in Eau Claire schools Any stage can be
transmitted from one person to another. - Nits
can be transmitted by use of another's comb -
Nymphs or adults can move from one clothing
article to another in a crowded cloakroom

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Importance of Pediculus humanus
1. _______________________ ______________________
___ A localized inflammation and itching occurs
at bite site from salivary secretions and louse
feces rubbed into wound.  
2. Vector of ____________________________________
_____  - causative agent is bacterium Rickettsia
prowazekii  
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Louse-borne Typhus vectored by Pediculus humanus
Pediculus picks up bacterium Rickettsi prowazekii
when feeding on infected person. Rickettsiae
multiply in louse's digestive tract are
released in louses ______________________. Ricket
tsiae are transmitted to a human when the
__________________________________________________
___ Louse is sensitive to ________________________
____ of infected host and
will leave that person for
another with normal temperature. Thus,
the disease is
transmitted from an infected person
to a non-infected
person and can occur in
epidemic proportions.
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Louse-borne Typhus
Large outbreaks of louse-borne typhus have been
associated with ________________________ where
mass migrations of refugees, poverty, and
crowding in prison camps have resulted in
epidemics.
The refugees of Rwanda and Burundi have fallen
victim to typhus
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Louse-borne Typhus
Disease is characterized by a high fever, body
rash, and CNS destruction. Mortality rate can
reach _______________ in epidemics. Treatment
with the antibiotic _________________________
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Phthirus pubis
Common names ____________________________________
____________ Adults have short, wide body - 1.5
to 2 mm long Last 2 pairs of legs are much
larger than the first pair. Hairy processes on
abdomen w on female ________________________
on male
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Phthirus pubis
Tarsi at the ends of 2nd and 3rd pairs of legs
are large and adapted for attachment to human
hair. Crab lice are adapted for life in
____________________ ______________________ of
humans - i.e. in pubic region, arm pits, beard,
and eyebrows.
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Phthirus pubis
Life cycle stages
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Importance of Phthirus pubis
Bite causes intense itching but NO diseases are
transmitted by it. Transmission is by close body
contact i.e. sexual intercourse French name for
crab louse is "papillion d'amour" - meaning?  In
Eau Claire, I seem to find them always on one
group of humans. Any idea what this group might
be?
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Phthirus pubis
Hairy lateral processes
SEM of crab louse - photo taken by my graduate
student who found in on a friend
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One Louse of Veterinary ImportanceHaematopinus
suis - pig louse
Large louse on pigs will bite humans if
available - recognized by large size - 4 mm
long - elongate head - round abdomen with
distinct lateral abdominal plates
__________________
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Haematopinus suis - pig louse
Causes severe infestation of pigs - irritation,
weight loss, and anemia in heavy infestations -
economic loss to pig farmer  Other species of
Haematopinus occur on ____________________________
___
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Control of Human Lice - both species
Delousing involves use of insecticide  - in WWII
DDT dust was used - today lotions or shampoos
containing _________________________________ are
used - common one is "Rid" - all stages of lice
are killed with this insecticide Problem
_____________________________ ____________________
_________________ Good personal hygiene and
laundering of clothes in hot water also helps
keep down the lice population.  
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Delousing can also be accomplished by
___________________________
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ORDER HEMPITERA - Chapter 36
____________________________________ Two families
of medical importance. FAMILY REDUVIIDAE -
Assassin bugs, kissing bugs, vinchucas Vectors
of _________________________________ caused by
_________________________________ in
Central and South America.  
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FAMILY CIMICIDAE - ____________________________
Cimex lectularius - Cosmopolitan in
distribution. Morphology - wingless, reddish
brown bug - 5-8 mm in length Adults are
recognized by broad first segment of the
thorax called the __________________________ 3
pair of legs are thin and modified for running.  
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Cimex lectularius
Males are easily recognized by fang-like
__________________________at the posterior end of
abdomen. Copulation is by traumatic
insemination.
Females are identified by presence of
___________________________ in the 5th abdominal
segment.
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Life Cycle of Cimex lectularius
______________________________ metamorphosis Eggs
hatch into ____________________ which must take
blood meal before molting into ___________________
___ Both males and females are blood feeders.
Mouthparts are modified to suck blood from the
dermis layer of the skin. Takes a bedbug 10 to 15
minutes to take a blood meal.
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Life Cycle of Cimex lectularius
Bedbugs are ____________________________ and
emerge from daytime hiding places in bedding,
mattress, walls, etc. to feed usually before
dawn. Bites cause little reaction in some persons
to considerable inflammation in others
due to allergic reaction to bug's saliva. Other
problem _______________________________________ D
iseases are transmitted by bedbugs
______________________ They are controlled by
spraying insecticides in areas where they
rest during the day.  
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Insects with Complete MetamorphosisORDER
SIPHONAPTERA - fleas - Chapter 38

• Fleas are small insects which have had a
  tremendous impact on human civilization.
• Fleas are vectors of ____________________________
  which has killed millions of persons from the
  dawn of civilization until today.
• Pandemic (world-wide epidemic) occurred in
  1500s and killed 1/4 of the worlds population -
  25 million people.
• A few cases in the U.S. even today

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Morphology of a Flea
Fleas are ________________________________________
____________ (allows them to move easily through
hairs of their hosts).
Adults are tan to dark brown in color. Contain
numerous bristles and spines. Mouthparts are
modified for sucking blood. 3 pairs of legs are
designed for jumping. At posterior end is the
_____________________________ used to detect air
currents and ________________ from potential
hosts.  
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Morphology of a Flea
Females have an elongate abdomen containing a
___________________________ for storage of sperm
after copulation.
Males have a shorter abdomen containing an
elaborate copulatory apparatus with
spring-like ___________________________ - the
largest of any animal in relation to body size!  
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Life Cycle of the Flea
Life cycle involves _____________________metamorph
osis.   1. Eggs deposited in hair of host which
drop off host in nest area. 2.
____________________ ______________________ and
feed on debris in the nest.
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Life Cycle of the Flea
3. After 9-15 days, the larva forms a cocoon and
becomes a ______________________ Pupal stage may
last a few days to a year depending upon
environmental conditions. 4. ___________________
emerges from pupal cocoon and awaits the presence
of a host - jumps on host when available.  


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Species of Fleas
2000 species of fleas have been described. Most
are ectoparasites of ___________________________
(only about 100 species occur on
birds). _____________________________ mammals are
most common hosts of fleas mammals with no
permanent habitations have few fleas. Fleas have
preferred hosts but will bite almost any mammal
if the opportunity arises commonly
move from one host to another.
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Fleas to examine in lab
Common names are associated with preferred
hosts. Pulex irritans - _________________________
_______ Echidnophaga - _________________________
____ Ctenocephalides canis - ____________________
______   Ctenocephalides felis -
___________________________   Diamanus -
_________________________________  
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Identification of Fleas
Species of fleas are distinquished by the
presence or absence rows of spines on the head
and/or thorax. - _____________________________
___occurs on the head - ______________________
__________occurs on the thorax    
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Pulex irritans
Human flea identified by _______________________
___________ ______________________________________
__________________ Adults will bite many other
mammals as well as humans.
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Pulex irritans
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Echidnophaga
Sticktight flea of Chickens. Will bite other
mammals including humans. ID by
_________________________ ________________________
______ ______________________________ Attaches
with mouthparts for long periods of time causing
severe ulcerations of the skin of chickens
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Ctenocephalides canis and Ctenocephalides felis
Dog and cat fleas. Recognized by presence of
_________________________ ________________________
_ Both species will bite dogs and cats and vice
versa. Humans are commonly bitten when newly
emerged adults are looking for a dog or cat and
will jump onto a human.
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Ctenocephalides canis and Ctenocephalides felis
Species identification is based on comparison of
lengths of 1st and 2nd spines of
___________________________________
C. felis is identified by first spine of genal
comb being about ¾ length of second spine
C. canis is identified by first spine of genal
comb being about ½ length of second spine
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Diamanus
Ground squirrel flea. Recognized by presence of
_______________________ _______________________ Al
though preferring ground squirrels, they will
jump onto humans from ground squirrels that are
dead or dying from _______________________
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Importance of Fleas
1. Most fleas are occasional biters - bites
cause little damage to skin and cause only minor
itching. There are two exceptions - the
sticktight flea Echidnophaga gallinacea of
chickens attaches permanently to chicken skin
causing ulcerations in skin - the female
chigoe flea Tunga penetrans penetrates human skin
and causes____________________________ ___________
______________________ Tunga occurs in
____________________ ____________________________
______ (not in U.S.)  
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Importance of Fleas

• Cat and dog fleas serve as intermediate hosts of
  tapeworms -_______________________________________
  __________________________________________________
  _________
• 3. Many species serve as vector of
  _______________________
•  

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Biology of Plague
Plague is caused by ______________________________
____________________ (old name Pasteurella
pestis).  
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Biology of Plague
Plague is primarily a disease of
_________________________________ - 2 cycles
Humans are infected with plague when
___________________________________ ______________
__________________________________________________
__ Infected fleas leave rat or ground squirrel
host and bite the new human host.  
______________________________involves rats
fleas
________________________________involves ground
squirrels fleas
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Biology of Plague
Fleas are effective vectors as the bacteria
multiply rapidly within the flea's digestive
tract. Eventually the stomach fills with
bacteria that block it. To clear this blockage,
the flea will attempt to take a blood meal and
will regurgitate its meal back and forth until
the obstruction is cleared. Thus, a
large number of bacteria are inoculated into the
bite wound as the flea attempts to clear these
bacteria.  
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3 Forms of Plague
1. ____________________________ - most common
form   - characterized by swollen lymph nodes
in the groin or axillary region
- called a _________________   - other
symptoms are headache, fever, prostration, and
delirium   - fatal in 25-50 of cases
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3 Forms of Plague
2. _____________________________________ -
bacteria invade the circulatory system -
source of bacteria for new flea vectors 3.
_____________________________________ - bacteria
occur in lungs - this form is highly
contagious by droplet spray - flea vector
is no longer needed to transmit this form
  These are 100 fatal if not treated.  
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Why does plague kill?

• Bacteria cause pathology by releasing a
  _________________________________which acts on
  _________________________________of cells
• Electron transport system is destroyed
• ATP production ceases
•  
• Hemorrhaging occurs through the body.

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Vectors of Plague
Pulex, Ctenocephalides, Diamanus, and several
species of rat fleas are vectors. In the U.S.
one of these is most important which one?
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Plague in World
Pandemic of plague in the 1500's in Europe and
spread throughout the civilized world -
associated with __________________________________
__  
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Plague in World
  Plague is still present in the world today -
most associated with _____________________________
_________
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Plague in World
We have been averaging about 12 cases of
plague/year in U.S. (except for major outbreak in
1981)
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Plague in the U.S.
Plague in the U.S. only in the ___________________
_________ - almost every case is associated with
dead or dying rodents
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Treatment of Plague
TREATMENT OF PLAGUE - ____________________________
_____ are effective treatment must be done over
a long time to be sure that the bacterial toxin
is eliminated slowly A
___________________________ is also available as
a preventative.
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Flea Control
CONTROL OF FLEAS - use of insecticides - use on
pets and sleeping areas. 1. Spray sleeping
area with _____________________________ -
kills larvae and pupae. 2. _____________________
_______ utilize slow release vapors - somewhat
effective.
3. ____________________________
- oral pill
taken by dog or cat. Drug enters
bloodstream and when
ingested by flea
disrupts egg development.  
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Flea Control

• 4. ________________________, ___________________
  ____, and ___________________________ -
  topical insecticides that are placed on pets
  skin drug wicks through skin and is ingested
  during flea bite.
• Kills fleas when ingested.
• Some also say they kill ticks and mosquitoes
  (to prevent _______________________________)
•  
•  

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ORDER DIPTERA fliesChapter 39
Flies are the most important group of vectors of
diseases.   A few are actually parasites
themselves. Well look at them a group at a
time.  
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Mosquitoes
Vectors of ____________________ -
_____________________mosquitoes Vectors of
filariasis (____________________________) - many
species Vectors of _____________________
______________________________-
_____________________mosquitoes Vectors of
____________________ (arthropod borne viruses) -
viruses that utilize an arthropod in its
transmission
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Arboviruses vectored by Mosquitoes
1. ______________________________________-
occurs in Central and South America and tropical
Africa Vector is ______________________________-
determined by Walter Reed in 1900 Disease is
characterized by high fever, jaundice, and
internal hemorrhaging (20 mortality).
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Arboviruses vectored by Mosquitoes
Yellow fever virus cont Normal hosts are
__________________________________ No treatment
but vaccine available Mosquito control is
important in preventing this disease (shown by
____________________________________ in Panama)  
human
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Arboviruses vectored by Mosquitoes
2. Encephalitis viruses Many viruses which
invade the CNS - disease is characterized by high
fever and headaches.  
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a. Venezuelan Equine Encephalitis Occurs in
horses and humans in South America a few cases
have been reported in Florida. Many species of
_______________________ mosquitoes and
_______________________blackflies are vectors of
this disease Virus normally cycles through
________________________________

causing no pathology. Virus causes high
mortality in horses (65)
but little
mortality in humans (1).
horses
humans
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• Eastern Equine Encephalitis
• Virus primarily cycles between ___________________
  ___ and ______________________mosquitoes
• Disease occurs primarily along the Atlantic
  Seaboard.
• If infected mosquitoes bite horses or humans,
  severe encephalitis results.
• Deadly! Mortality rate in horses is 90 and in
  humans (primarily children) is 30.
•  

horses
children
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c. Western Equine Encephalitis  _________________
__________________ mosquito maintenance
cycle.  Disease occurs west of the Mississippi
River  Infection results in a mild CNS disease
and is rarely fatal in horses and children
(adults are not affected).  
horses
children
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d. St. Louis Encephalitis Disease occurs in the
Midwest _________________________________
mosquito cycle   Horses are not involved disease
affects only _________________________ -
generally not fatal.
Older humans
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e. LaCrosse Encephalitis One of a group of
related encephalitis viruses all are referred
to as the California Group Encephalitis Cycle
___________________________ Over 1000 human cases
have been reported in the Midwest Virus
primarily infects children under 14

symptoms are headache, mental confusion,
and
nervous system damage. 2 deaths in children in
Wisconsin
Children
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f. West Nile Encephalitis
First identified in New York in 1999 - 62 human
cases resulted in 7 deaths In 2003 there were
9862 cases and 264 deaths in the U.S. In 2007
there were 3623 cases and 134 deaths in the U.S.
Note where largest number of cases are.
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f. West Nile Encephalitis
Life Cycle involves _____________________________
______________
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f. West Nile Encephalitis
Reported on 2001 in birds in Milwaukee area
Human cases reported throughout state in
2002 Numbers - ___________________________________
_______________
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f. West Nile Encephalitis
Humans at greatest risk are ______________________
__________________________________________________
Horses are also affected. Virus enters the CNS
and causes inflammation of the meninges around
the brain and the spinal cord. Symptoms include
headache, high fever, neck stiffness,
disorientation, tremors, and muscle weakness.
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Other Dipterans as Vectors
Deerflies (Chrysops) - vector of
_________________________ Tsetse flies (Glossina)
- vector of African Sleeping sickness
caused by ___________________
_________________ Sandflies (Phlebotomus
Lutzomyia) - vectors of __________________________
_____________ Blackflies (Simulium) - vectors of
________________________________________
VEE Houseflies (Musca domestica) - phoresis of
bacteria and protozoan cysts from feces  
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Dipterans as Parasites
Infection of vertebrates by fly larvae (maggots)
is called ___________________________________ 1.
__________________________________________________
Adults are greenish-blue flies which deposit
eggs in livestock or human skin wounds and larvae
will live in the skin.
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Dipterans as Parasites
2. _____________________________ -
Gasterophilus intestinalis Adult bot flies lay
eggs on hairs which are ingested by licking
horses Larvae live in the horse's stomach and
feed on blood - cause considerable damage to
stomach mucosa of the horse.  
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Dipterans as Parasites
3. _______________________________ - 2 species
of Hypoderma Adult heel flies bite legs of
cattle and lay eggs in the wound. Larvae hatch
and migrate to the lumbar region where they live
beneath the skin. Larvae cut a breathing hole in
the hide causing economic loss - hides are
worthless.