Glossary of Ectoparasites and vectors

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What are the three stages of a gradual metamorphosis?
What are the four stages of a complete metamorphosis?
What two diseases are houseflies thought to be a vector for?
1.Bacterial dysentary
About how many days are required for a housefly egg to mature into a reproductive adult?
~10 days
Do lice show a gradual or complete metamorphosis?
Describe the appearance of lice.
They are flat and resemble walking birthmarks.
Head lice and body lice are similar in that they both suck blood. What feature separates them?
They do not interbreed.
Where does each species of lice lay its eggs?
*Head lice: hair shafts
*Body lice: seams of clothing
How are lice treated? Are they able to survive off of the human body?
*insecticide lotions and creams
*adults can survive 10 days off of the host, nits much longer
Name three diseases that lice serve as a vector for.
1.epidemic typhus (rickettsia prowazecki)
2.trench fever (rickettsia quintana)
3.Relapsing fever (borrelia recurrentis)
Describe the metamorphosis of fleas.
Complete with 3 larval instars and pupa stages.
How many legs does a flea have? Describe their special adaptations.
*6 legs
*hind pair have resilin which endow jumping ability
*also legs have hooks to grab onto hair or fur
An unfed flea can survive for only three months.
False: an unfed flea can survive three years in high humidity.
Where does the sand flea or chigger commonly bite?
Penetrates the skin at the nail base or between the toes; painful and irritating.
Name two diseases fro which the flea is a vector.
1.Yersinia pestsis
2.Endemic typhus (rickettsia typhii/mooseri)
One bacillus carried by the flea causes a special adaptation that faciltates its spread. What is the bacillus and what is this adaptation?
*yersinia pestis
*proventricular blockage causes regurgitation of the bacillus
Describe the metamorphosis of the chelicerata.
Gradual: larva (6 legs), nymph, adult (8 legs).
Describe the appearance of argasids. What are their feeding habits?
*soft ticks, head not visible
*nocturnal feeders, stay on host for only a few minutes
Describe the appearance of ixodidae.
*hard ticks, head visible, dorsum scutum (shield)
Describe the life cycle of ixodidae.
*female drops off host and lays eggs
*larvae find host, feed for several days and drop off
*larvae molt on ground into nymphs, which find a host, feed 4-8 days, and drop off
*molts into adult, which finds a host, mates, feeds for several days and drops off
What special adaptations do ixodidae have to allow them to find a host? to sense ground vibrations
2.Haller's organs on front legs respond to odors, temperature, and carbon dioxide
How do ticks find a place to bite on the host?
*Haller's organs
*chelicerae sense ATP
What two organs does the tick use to attach to a host?
*checlicerae: pierce skin
*hypostome: anchor
How much weight does a tick gain during engorgement?
How do male ticks attract a mate?
Secretion of a blend of phenols.
What are three methods of control of ticks and tick-borne illness?
How many ticks are necessary to cause tick paralysis? What is the latent period before symptoms appear?
*a single female tick
*5-7 days
Ticks are known to be vectors for at least 8 diseases. Name 5 of them.
3.Lyme disease
5.East coast fever
6.Endemic relapsing fever
7.Coxiella burnetti (Q fever)
8.Congo-Crimean hemorrhagic fever
what is the life cycle of the mite?
3.Nymph (2-3 stages)
How do larger mites breathe? How do smaller mites breathe?
*larger: through stigmata
*smaller: cutaneously
How big is an adult sarcoptes scabei? With what two conditions is it associated?
*Scabies in humans and mange in animals
Why do dust mites prefer a humid environment?
They are able to extract water from the air.
How are dust mites commonly raised in the lab?
On beard clippings from an electric razor.
What two diseases are mites vectors for?
1.Scrub typhus
2.Rickettsial pox
What is the target of pyrethrins and DDT?
Block voltage-gated sodium channel to slow nerve conduction.
How do organophosphates and carbamates work?
Target ACh-esterase; bind serine to prevent recyling of ACh in the synapse.
Name two ways ectoparasites have developed resistance to insecticides.
1.Point mutations in target
2.Detoxifying enzymes

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