Fleas: Biology and Taxonomy

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Questions and Answers

How long can adult fleas remain active inside their cocoon?

4-12 months (correct)

1-3 months

A few days to a week

Up to 6 months

How many times their own weight in blood can nymphs ingest?

6-12 times (correct)

4-6 times

2-4 times

12-16 times

What is the shape of the proboscis of the insect?

Long and zigzagged

Thin and straight (correct)

Thick and curved

Short and stout

What is the primary reason for the bugs' defecation during or soon after feeding?

For disease transmission Signup and view all the answers

What is the maximum duration a flea can survive without a blood meal?

Up to 6 months Signup and view all the answers

Approximately how many species of fleas exist?

2200 Signup and view all the answers

What is the average number of eggs laid by a female insect in its lifetime?

200-300 Signup and view all the answers

What is the main function of the proventriculus in fleas?

To prevent regurgitation of blood Signup and view all the answers

Why is it medically important to know that fleas will abandon their host if it dies?

Because it allows fleas to transmit diseases to other hosts Signup and view all the answers

How long does it typically take for the complete life cycle of these insects to occur?

3-10 months Signup and view all the answers

Where do female insects typically lay their eggs?

In mud walls or cracks in walls and floors Signup and view all the answers

How do fleas move on their host?

By crawling Signup and view all the answers

Why do hungry adults and nymphs sometimes pierce the swollen abdomen of an engorged nymph?

To feed on the nymph's blood Signup and view all the answers

What is unique about the flea species Tunga penetrans?

It burrows into people's feet Signup and view all the answers

What is the purpose of the genal combs in some flea species?

To defend against predators Signup and view all the answers

How many nymph instars are there in the life cycle of the insect?

5 Signup and view all the answers

What is the maximum vertical distance a flea can jump?

20cm Signup and view all the answers

What is the typical duration of feeding for these insects?

10-25 minutes Signup and view all the answers

Where do female fleas typically lay their eggs?

In debris or detritus Signup and view all the answers

What is the maximum lifespan of an adult insect in the absence of hosts?

4-6 months Signup and view all the answers

How do fleas jump?

Using a molecular spring link trigger Signup and view all the answers

What is the typical size of the eggs laid by the female insect?

1.5-2.5mm Signup and view all the answers

What triggers the emergence of adult fleas from their pupae?

Vibrations from an animal moving nearby Signup and view all the answers

How long does it take for the eggs to hatch?

10-15 days Signup and view all the answers

What is the most common nuisance flea species in the US?

Ctenocephalides felis Signup and view all the answers

What is the function of the silk produced by larval fleas?

To create a protective cocoon Signup and view all the answers

What is one of the main reasons for the medical importance of fleas?

They can cause discomfort and irritation to their hosts Signup and view all the answers

What is the color of the eggs laid by the female insect?

White, pearly, pink, or yellowish Signup and view all the answers

How many blood meals do the nymphs require?

One per instar Signup and view all the answers

What is the purpose of the flea's powerful hind legs?

To jump long distances Signup and view all the answers

How many eggs can a female flea lay during her lifetime?

300-1000 Signup and view all the answers

How long does the larval period of fleas typically last?

2-3 weeks Signup and view all the answers

How do people typically get infected with Chagas disease?

By scratching the feces of the insect into their skin Signup and view all the answers

What is the number of triatomine species that have been found to be infected naturally?

70 Signup and view all the answers

What determines the vector efficiency of triatomine insects?

Speed of feeding and defecation rate Signup and view all the answers

Which of the following is a non-pathogenic species of trypanosome?

Trypanosoma rangeli Signup and view all the answers

What is the primary host of the trypanosome parasite?

Wild animals Signup and view all the answers

What percentage of triatomines in an area may be infected?

25 to 50% Signup and view all the answers

What is another way people can get infected with Chagas disease?

By eating infected bugs or animals Signup and view all the answers

Where is Chagas disease most common?

Central and South America Signup and view all the answers

Study Notes

Fleas

Order Siphonaptera: 2200 species, 220 genera, with only a few important to humans
94% of fleas bite mammals, while the remainder feed on birds
Worldwide distribution, with many species and genera having limited ranges

General Taxonomy

Medically important genus: Xenopsylla
Other genera with medically important roles: Ctenocephalides (hosts for cestodes)
One flea species (Tunga penetrans) "burrows" into people's feet

Morphology

Adults: 1-6mm, oval shaped, compressed laterally, light to dark brown, with small bristles and spines
Lack wings, but have powerful legs, with hind legs specialized for jumping
Females: tip of the abdomen is more rounded
Head: triangular, with conspicuous eyes, club-shaped antennae, and mouthparts pointing downward
Some species have tooth-like spines called genal combs

Role of Blood Feeding

Both sexes take blood meals, with saliva injected during feeding containing anticoagulants
Blood sucked through pharynx into proventriculus, with backwards pointing spines to prevent regurgitation
Proventriculus is important for disease transmission
Blood enters mid-gut for digestion

Life Cycle

Female deposits eggs in debris or detritus, often in habitat or dwelling where host lives (nest, burrow, etc.)
Eggs: small (0.1-0.5mm), oval, yellow or white, with female laying 300-1000 eggs during her lifetime
Eggs hatch after 2-5 days, with legless larva emerging
Larval period: 2-3 weeks, may be up to 200 days
Pupae: white cocoon made of silk, with silk being sticky and picking up bits of dust, dirt, and debris
Adults emerge after 2-3 weeks, with stimulus required for emergence usually being a vibration of an animal moving nearby or carbon dioxide

Adults

Can live anywhere from 10 days to 12 months
Avoid light, usually hiding among the hair or feathers of the host (or clothing, in beds)
During feeding, feces are evacuated to make room for blood meal
Presence of flea feces (sometimes partially digested blood) can be seen in bed linens of infested houses

Host Specificity

Most fleas have a slight preference for a specific host, but will bite other hosts when their preferred host is absent
If a host dies, fleas will abandon host for a new one
Some fleas can tolerate desiccation, starvation (up to 6 months), and can jump up to 20cm vertically or 30cm horizontally

Medical Importance

Four main reasons for medical importance: Nuisance, Plague, Murine Typhus, and Cestodes
Nuisance aspect: flea bites result in discomfort, swelling, and irritation, with cat fleas being the most common nuisance species in the US

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Description

Learn about the biology, taxonomy, and medically important aspects of fleas, including their species, genera, and distribution. This quiz covers the morphology, feeding habits, and characteristics of fleas.