Insects as Disease Vectors

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Insects as Disease Vectors
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Section XIV - Insects as Vectors Of Disease
Page 106 in Manual
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C. Disease transmission by insects.
1. Plant pathogens. In Increasing order of
dependence upon vectors fungi-
bacteria viruses mycoplasmas (phytoplasmas)
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C. Disease transmission by insects.
1. Plant pathogens.
a. Fungi (most important plant pathogens).
Example Brown rot of Peach Transmission
enhanced by plum curculio
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Brown Rot of Peach
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C. Disease transmission by insects.
1. Plant pathogens.
a. Fungi (most important plant pathogens).
b. Bacteria.
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• Increase survival

Protect bacteria from environment
Example curcubit wilt bacteria Overwinter in
cucumber beetle (which also acts as a vector)
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Cucumber wilt
Cucumber beetles
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(1) Increase survival.
(2) Dissemination.
Example potato black leg bacteria Disseminated
by fruit flies.
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Potato blackleg bacteria on stem and tuber



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(1) Increase survival.
(2) Dissemination.
(3) Inoculation.
Example fire blight of apple and
pear Inoculated into nectar of blossoms During
pollination visits.
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Fireblight Bacteria Transmitted by honey bees
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c. Viruses (second most important pathogens).
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c. Viruses (second most important
pathogens). Vectors of viruses include
Aphids
Example Cucumber mosaic virus Transmitted by
Green Peach aphid
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c. Viruses (second most important
pathogens). Vectors of viruses include
Leaf hoppers
Example Sugar beet curly top virus Transmitted
by a leaf hoppers
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d. Mycoplasma-like organisms.
Those that infect plants now called Phytoplasmas
Phytoplasmas are minute, wall-less prokaryotes,
(the smallest free living organisms)
Associated with a number of plant diseases, and
vectored primarily by Leafhoppers and
planthoppers)
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d. Mycoplasma-like organisms.
Most dependent on vectors
Example Elm Yellows vectored By Elm Leafhopper
(Elm yellows said to Have killed More Elms that
DED) Some phytoplasmas multiply in Host and
vector
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2. Animal Vectors.
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2. Animal Vectors.
a. Vectors. Most vectors are blood feeders.
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2. Animal Vectors.
a. Vectors. Most vectors are blood feeders.
(1) Diptera
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2. Animal Vectors.
a. Vectors. Most vectors are blood feeders.
(1) Diptera
(a) Mosquitoes.
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Mosquito biology video clip
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2. Animal Vectors.
a. Vectors. Most vectors are blood feeders.
(1) Diptera
(a) Mosquitoes.
(b) Black flies.
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2. Animal Vectors.
a. Vectors. Most vectors are blood feeders.
(1) Diptera
(a) Mosquitoes.
(b) Black flies.
(c) Sand flies.
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2. Animal Vectors.
a. Vectors. Most vectors are blood feeders.
(1) Diptera
(a) Mosquitoes.
(b) Black flies.
(c) Sand flies.
(d) Tsetse flies.
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(2) Other insects
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(2) Other insects
(a) Triatomid bugs.
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(2) Other insects
(a) Triatomid bugs.
(b) Fleas
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(2) Other insects
(a) Triatomid bugs.
(b) Fleas
(c) Lice
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(2) Other insects
(a) Triatomid bugs.
(b) Fleas
(c) Lice
(3) Other arthropods
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(2) Other insects
(a) Triatomid bugs.
(b) Fleas
(c) Lice
(3) Other arthropods
(a) Ticks
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Lime Disease video clip
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(2) Other insects
(a) Triatomid bugs.
(b) Fleas
(c) Lice
(3) Other arthropods
(a) Ticks
(b) Mites
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Follicle mite video clip
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b. Diseases.

• Malaria caused by a
• protozoa,

Each year, 300-500 million people become ill with
malaria. Several million die. 200-300
children die from malaria each hour.

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Malaria most important tropical parasitic
disease. kills more people than any
communicable disease except tuberculosis..
Malaria is caused by any of 4 species of
Plasmodium protozoa transmitted by mosquitoes
Curable if promptly diagnosed and treated.
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b. Diseases.
(1) Malaria--protozoa, Plasmodium.
(a) Vector--Anopheles sp. (species varies with
location.)
Anopheles sp.
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(No Transcript)
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Malaria Video clip
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b. Diseases.
(2) Lymphatic Filariasis - Elephantiasis.
A microfilaria as it Would appear In a blood smear
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Several species of mosquitoes transmit
Microfilaria to humans. These reside in
the Lymph system Repeated infections result in
blockage of the lymph ducts, accumulation of
fluid and swelling of the tissues.
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Bancrofti filarasis (elephantiasis)
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b. Diseases.
(2) Filariasis - elephantiasis.
Generally Non-lethal, But with traumatic
symptoms. After infection, No cure (other than
amputation) Preventive drugs now available
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(b) Vectors--many species include Anopheles,
Culex mosquitoes.
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Lymphatic Filariasis
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(3) Yellow fever (one of arboviruses).
Dr. Jesse Lazear died of Yellow fever during study
Dr. Walter Reed Director of Program
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(3) Yellow fever
(a) Many vectors-- especially Aedes sp.
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Yellow fever and Malaria Clip
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(3) Yellow fever
(a) Many vectors-- especially Aedes sp.
(b) Other viruses include encephalitis,WEE,EEE,ST
.LV
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Western, Eastern, St. Louis Equine Encephalitis
Video (about 1963)
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(No Transcript)
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(4) Onchocerciasis (river blindness)
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(4) Onchocerciasis (river blindness).
(a) Microfilaria- gradual infection,
blindness, 20, other--look old
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River blindness(onchocerciasis) spread by a
blackfly. It deposits larvae of a parasitic
worm on the body, which produces millions of
microfilaria. These migrate throughout the
body, causing incessant itching. In addition,
they can cause blindness when they enter the
eyes. Approximately 770,000 people in
tropical countries suffer serious sight
impairment, 270,000 of whom are blind.
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(4) Onchocerciasis (river blindness).
(a) Microfilaria- gradual infection,
blindness, 20, other--look old
(b) Vector- black flies, Simulium sp.
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(5) Trypanosomiasis (sleeping sickness).
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(5) Trypanosomiasis (sleeping sickness).
(a) Trypanosomas, cause sleep,coma,death.
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(5) Trypanosomiasis (sleeping sickness).
(a) Trypanosomas, cause sleep,coma,death.
(b) Vector--Tsetse flies.
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c. Other vectors Fleas
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Flea biology video clip
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c. Other vectors and primary diseases.
(1) Fleas - Bubonic Plague (bacteria)
The Black Death
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The Black Death kills Quickly My friend Had
lunch With me and Dinner in Paradise
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Rat Receiving Station San Francisco
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Black Death (Bubonic Plague) video clip
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(No Transcript)
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c. Other vectors and primary diseases.
(1) Fleas - Black Plague (bacteria)
(2) Lice - Typhus (Rickettsia).
Until recent times, Typhus killed more Soldiers
than the enemy
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c. Other vectors and primary diseases.
(1) Fleas - Black Plague (bacteria)
(2) Lice - Typhus (Rickettsia).
(3) Ticks - Lyme Disease (bacteria)
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c. Other vectors and primary diseases.
(1) Fleas - Black Plague (bacteria)
(2) Lice - Typhus (Rickettsia).
(3) Ticks - Lyme Disease (bacteria)
- Rocky mountain spotted fever
(Rickettsia).
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