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?
- 1.able 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
- 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
- Ticks are known to be vectors for at least 8 diseases. Name 5 of them.
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
- 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
- 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
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