introduction to ectoparasites

what class of arthropods do fleas belong to and why?

insecta because they have 1 pair or anteanae and three pairs of legs

what is an arthropod?

invertebrates with hard chitinous exoskeleton, segmented bodies, and jointed limbs

what are the two types of arthropods?

1. insects

2. arachnids

what arthropods are insects?

1. flies

2. fleas

3. lice

4. true bugs

what arthropods are arachnids?

1. mites

2. ticks

how many legs do insects have?

six

what is an important distinguishing feature of insects?

they have a DISTINCT head, thorax, and abdomen in adults

what are life cycle (s) of insects?

partial or complete metamorphosis

which arthropod has a single pair of antennae in adults?

insects

how many legs do arachnids have in the larval stage?

six

how many legs do arachnids have in the nymph and adult stage?

eight

how many segments do arachnids have?

two segments

what is the physiology of arachnids?

1. mouthpart

2. fused cephalothorax and abdomen

which arthropod do not have antennae?

arachnids

what is an important distinguishing factor that arachnids possess in their development compared to insects?

arachnids do not pupate

describe the development of arachnids

simple development; babies look like "mini versions" of adults

how many segments do insects have?

three

modified complete metamorphosis

larvae are retained within the body of female and will undergo pupation after being deposited on host

what are examples of arthropods that undergo modified complete metamorphosis?

1. nasal bot fly

2. sheep ked

mayflies life cycle is classified as incomplete metamorphosis because...

there is no pupa stage

what is the difference between a vector and fomite?

vector= pathogen carried WITHIN them

fomite= pathogen carried ON them

what are the different adaptations (of their mouthparts) parasites have for feeding?

1. adapted for chewing at skin scales and hair

2. act like sponge for secretion at mucous membranes or blood

3. adapted for tearing host tissue

what are the types of transmission of arthropods?

1. mechanical transmission

2. biological transmistion

what type of transmission does not have development of pathogens?

mechanical transmission

what type of transmission allows pathogen development and moves from the gut to mouthparts for transmission?

biological transmission

biological transmission

pathogen is transferred between hosts and arthropod

what are insect juveniles referred as?

larvae, maggots, or grubs

what are juvenile insects adapted for?

feeding and growth

what are adult insects adapted for?

reproduction and dispersal

what happens during the metamorphosis within the pupa stage of the insect?

reorganization and reconstruction of the entire body

partial metamorphosis in insects

new cuticle is made and old cuticle shed at 4-5 intervals throughout development; each new stage the insect increases in size

explain how the insect looks during partial metamorphosis

juvenile stages broadly resemble adults

what is key about the arachnid life cycle?

they only go through partial metamorphosis

what are the stages of partial metamorphosis in arachnids?

1. egg

2. 6-legged larva

3. 8-legged nymph

4. 8-legged adult

what is important about incomplete metamorphosis?

no pupation stage meaning adults and nymphs are almost identical

what is important about complete metamorphosis?

has a pupation stage meaning adults and larvae are very different morphologically

what are the feature of lice?

insects modified for parasitisim, flattened dorso-ventrally, and wingless

can you as an owner get lice from your pet or livestock?

no, they are highly host-specific

what are the typical hosts to lice species?

mammals and birds

what are the two main groups of lice?

1. anoplura (sucking lice)

2. mallophaga (biting/chewing lice)

what is the main identifying factor for anoplura?

head is more narrow than thorax

what is the main identifying factor for mallophaga?

head is broader than thorax

what is the life cycle of lice?

incomplete metamorphisis; they are always a parasite for their life

how long do lice remain on their host?

30 days

how long are lice able to survive off their host?

usually unable to survive more than 1-2 days off host

what are the implications of the louse life cycle in vet med?

do not need to treat environmentally as they will be dead anyway in 2 days time

how do lice transfer from one host to another?

transfer by direct contact in close proximity since they do not have wings

why do lice appear in sheep and cattle in higher concentrations during late autumn and winter?

1. animals kept in barns in close proximity

2. animals have "winter coat" in which they can better hide themselves

diagnosis of lice

1. nits (eggs) attach to follicle of fur

2. identify adults using magnifying glass

what can clinical sign can anoplura cause in animals?

anemia

what clinical sign can mallophage cause in animals?

skin irritation, pruritis, and alopecia

what are the general features of fleas?

wingless and laterally compressed

what are important features of fleas used for identification?

1. laterally compressed

2. recessed, club-like antennae

3. combs

what are the three main fleas?

1. cat flea/dog flea

2. oriental rat flea

3. sticktight flea

what is the life cycle of a flea?

complex metamorphosis

what do drugs that treat fleas target in their life cycle?

target chitin synthesis of flea to flea from hatching

the larvae of fleas are an intermediate host for...

tapeworm proglottids

what is important about the pupa life stage of fleas?

1. chemical resistant

2. hibernate until stimulated to emerge

where can you find the pupa stage of fleas in the environment?

carpets

what stimulates flea pupa to emerge as adults?

vibrations and carbon dioxide

what is the lifespan of adult fleas?

2-3 months

how long can adult fleas survive without a host?

2 weeks

what is important about flea pathology?

they are vectors for other pathogens

what percentage of fleas live in the environment?

95%

what percentage of fleas live on the animal?

5%

what is the primary cause for transmission of fleas?

new emerged fleas from an infested environment

how do we diagnose fleas?

use a flea comb to see flea dirt; the eggs are in the environment NOT on the animal's fur

where do fleas lay their eggs?

on the host but it will after fall off into the environment only leaving the flea dirt

what do adult flies feed on?

1. blood

2. saliva

3. tears

4. mucus

what can flies spread?

1. bacteria

2. viruses

3. parasites

what are the different types of flies?

1. biting flies

2. nonbiting flies

3. myiasis

what do biting flies feed on?

blood

what can happen from biting flies?

bites can be painful and may cause an allergic reaction

what do nonbiting flies feed on?

bodily secretions

myiasis (fly strike)

LARVAE develop in the subcutaneous tissues or organs of animals

what type of metamorphosis do flies have?

complete metamorphosis

what stage of adult fly do not parasitize?

free-living

what are the different groups of flies?

1. tabanids

2. muscids, calliphorids, and botflies

3. lower flies

what is the importance of tabanids?

blood loss, vectors

what tabanid causes problems and acts as the vector?

only female adults

what is the importance of muscids, calliphorids, and botflies?

vectors and economic loss

what is the importance of lower flies?

annoyance, intermediate hosts, and vectors

what serves as vectors in lower flies?

the adult females

what are the only type parasitic life cycle are the larvae parasitic?

type 1

what type of flies are type 1 parasite flies?

1. blow flies

2. some bot flies

describe the adults of type 1 parasitic flies life cycle.

adults are free living and non-parasitic

what type of parasitic fly life cycle are the adult females parasitic?

type 2

what are examples of type 2 parasitic flies?

1. houseflies

2. mosquitos

3. midges

what are examples of type 3 parasitic flies?

keds (sheep) and tsetse flies

what occurs in the type 3 parasitic flies life cycle?

larvae develop one at a time in the mother fly; adult = parasitic

what life stage of flies causes myiasis?

larvae

what type of arthropod are mites?

arachnids

what are the size of mites?

microscopic

what do mites feed on?

host tissue and cellular debris

how many segments do mites have?

2

gnathosoma

head and throrax in mites

idiosoma

abdomen in mites

how many legs do nymphs and adult mites have?

8

how many legs do larvae mites have?

6

what are the types of parasitic mites?

1. mange mites

2. ear mites

3. nasal mites

4. chigger