Intro to arthropods L28 | Parasitology Final Exam

What structures form the stout tube of arthropod feeding

• chelicerae

• hypostome

As part of the stout tube, What is the purpose of the chelicerae

jaw-like cutting the epidermis

As part of the stout tube, What is the purpose of the hypostome

for blood feeding

With mechanical transmission of pathogens, how does the pathogen develop within vector

no development of pathogens w/in vector

With biological transmission of pathogens, how does the pathogen develop within vector

development of pathogen within the vector moving from gut to the mouthparts for transmission

In insecta life cycle. what are the two stages of complete metamorphosis (and their purpose)

• juveline stage: larvae, maggots - for feeding and growth

• adult stage: 3 pairs of legs w distinct head and abdomen - adults adapted for reproduction and disperal

In insecta life cycle, what stage has reorganization and reconstruction of the entire body during metamorphosis

pupa stage

In partial metamorphosis of insecta, juvenile stages are referred to as

nymphs

In partial metamorphosis of insecta, juvenile stages resemble what and what occurs with development after each stage

juvenile stages resemble adults and insect increases size at each stage

What are the characteristics of arachnida adults

• 4 pairs of legs in adults (and nymphs)

• mouthparts and fused cephlaothorax

• no antennae

(literally mites and ticks)

What is the four basic stages of arachnida (and leg number in each)

1. egg

2. larva - 3 pairs of legs

3. nymph - 4 pairs of legs

4. adult - 4 pairs of legs

What occurs between each arachnida life stage of development

moulting

When does mating occur in flea life cycle

only after a blood meal

With flea eggs, how do they develop in the environment

eggs fall off host and hatch yellow/white larvae that develop in carpets or bedding

With flea eggs, how long do eggs lay on host

Eggs lay on host for up to 20 days

What are flea larvae’s affinity with light and motion

flea larvae are negatively phototoxic (seeking darkness) and positively geotoxic (moving downwards)

True or false: flea larvae feed on organic material while residing in carpets and cracks

true

Flea larvae emerging from pupae, have what type of affinity with light and motion

novel adults are positively phototoxic (seeking light) and negatively geotoxic (moving upwards)

True or false: novel flea adults (from pupae) are negatively geotoxic and negatively phototoxic

false; novel flea adults (from pupae) are negatively geotoxic and positively phototoxic

True or false: novel flea adults (from pupae) are positively geotoxic and positively phototoxic

false; novel flea adults (from pupae) are negatively geotoxic and positively phototoxic

True or false: flea larvae are positively geotoxic and negatively phototoxic

true

How do you dx presence of fleas and flea feces

• using flea comb to find fleas in pelage

• place flea feces on moist cotton wool or white paper

True or false: may not be possible to find fleas on cats that are fastidious groomers

true

What are the two types of flies

1. non-biting flies

2. biting flies

In non-biting flies, how does their mouthpart work

mouthparts act like a slasher for secretions at mucus membranes of blood

In biting flies, how does their mouthpart work

mouthparts act like a piecer for secretions at mucus membrane or blood

What are the similarities between egg lifecycle of fleas and flies

both flea and fly eggs:

• are laid onto host for up to 20 days

• move off host into environment

What do fly eggs develop into

fly eggs develop into larvae, legless maggots

How do fly pupae and adult form

after three larval stages which develops into pupa stage into adult

In type I parasitic fly life cycle, what stages are parasitic and free-living

• larvae are parasitic

• adults are free-living (and non-parasitic)

(ex. bot flies)

In type II parasitic fly life cycle, what stages are parasitic and free-living

• larvae are free-living (and non-parasitic)

• adults are parasitic

(ex. mosquitos)

In type III parasitic fly life cycle, how do larvae develop and which stage are parasitic

• larvae develop in mother fly

• adults are parasitic

(ex. tsetse flies)

True or false: once removed from host, most lice will die within one month

false; once removed from host, most lice will die within one week

What are the two types of lice

1. chewing lice

2. sucking lice

In distinguishing between the different types of lice, what are the important characteristics of chewing lice

1. mouthparts do not piece skin

2. head is broader than thorax

In distinguishing between the different types of lice, what are the important characteristics of sucking lice

1. mouthparts piece skin and suck blood from capillaries and skin

2. head is narrower than thorax

How long is transition from lice egg to adult in a single host

2-3 weeks

What is the kryptonite for adults living on host

heavy rainfall

What type of metamorphosis does lice have

partial metamorphosis

Where can you identify lice

in wool/hair or skin

How can louse antigens be dx

through wool samples

What type of effect does chewing lice have on economic impact of sheep herds

• lice infestion have no effects on liveweight or wool yield

• heavy infection, however, leads to reduce wool quality

What is an economic importance to the tanning industry from chewing lice

cockle

What is an important differential dx for sheep scab

louse

What are the two types of mites

• burrowing mites

• non-burrowing mites

What is the difference between burrowing and non-burrowing mites in terms of skin lesions, leg length, and size

• burrowing

  • burrow into skin

  • shorter legs

  • smaller

• non-burrowing

  • live on skin surface and hair

  • long legs

  • larger

Where do all developmental stages occur with life cycle of mite (how long does life cycle take to complete)

occur on host taking 3-4 wks to complete

How do you dx burrowing mites using skin scrape methods

deep skin scraping

How do you dx surface parasitic mites using skin scrape methods

tape stripping or superficial skin scraping

How do you dx hair follicle mites using skin scrape methods

squeezing pustules onto a slide

What are the three ancillary dx tests for mites

1. hematology

2. biochem

3. serology

What are the two types of ticks

HARD ticks

soft ticks

What type of arthropods are ticks

temparay arthropods

How many pairs of legs does larval stage of ticks have

3 pairs of legs

How many pairs of legs does nymph/adult stage of ticks have

4 pairs of legs

What is the most appropriate tx of tick removal

apply 70% alcohol or liquid soap to a cotton ball covering tick; tick will move off skin and attach to cotton ball

Why should you not use hot match for tick removal

explode tick gut causing release of pathogens

blow more pathogens into the skin