L21: Arthropods III (Vet/Med Significance)

What are the three primary groups, of insects, of veterinary importance?

– Lice

– Fleas

– Flies

Definition:

Hooked tarsi

– Terminal segments of legs, grip hair

What do chewing lice feed on?

– Mammals

– Birds

– Feed on skin

What do sucking lice feed on?

– Mammals only

– On blood

Summary:

lice (3)

– permanent ectoparasites

– Small, wingless dorso-ventral (DV) flattened body

- Host specific

How do lice cause harm to the host? (4)

– Irritation and skin damage

– Anemia

– Vectors of disease, organisms, like typhus, trench fever

– Intermediate host of parasites, like tapeworms

What does it mean to be host specific? (lice)

– lice will only attach to a specific host

Where does the lice lifecycle occur?

– On the host

What is the lice lifecycle?

1st nymph → 2nd nymph → 3rd nymph → female or male adult → female lays an egg

Life cycle is completely on host

Lice of animals (3)

– Sheep body louse

– Feeds on skin and wool

– Causes intense irritation

Hematopinus - blood sucking louse (pigs & rumiinants)

-lice that feeds on humans

-Pediculus humanus

-P. capitis

Phthirus pubis - pubic louse

Host specific

Sexual transmission

flea

summary:

fleas (3)

– non-permanent ectoparasites

–small laterally compressed adults

–muscular hind legs

Fleas:

Hosts

– Birds

– Mammals (dogs, cats, poultry, humans)

Fleas:

Eggs

Laid on host or in nest of host (kennels, blankets, etc.)

Fleas:

Larva (4)

– Detritus feeder

– Not on hosts

– Chewing mouth parts

– Feed on adult flea faeces and gain nutrition from blood in faeces (cats and dogs)

Adult flea

Blood feeder they have sucking mouth parts, adapted to piercing skin and feeding on blood

How do fleas cause harm to the host? (5)

–allergy or hypersensitivity

–Blood loss (especially in juveniles and elderly animals)

– Bacteria

– Virus

– Intermediate host to cucumber tapeworms

Fleas as bacterial vectors

– Plague

– Cat scratch fever (Bartonella)

Fleas as viral vectors

– Myxomatosis

dipylidium caninum

– Cucumber tapeworm of dogs and cats

– Life cycle of cat flea

Ctenocephalides felis

Examples of filth flies

– House flies

– Blowflies

flies and mosquitoes:

Blood sucking adult summary

– Stable flies and horseflies cause blood loss

– Vectors for malaria and heartworm and trypanosomiasis

Where do the larval stages of flies of mosquitoes live? (4)

– Blowfly and flesh fly maggots live in decomposing flesh

– Strike fly maggots live in living tissue

– bot fly maggots live in internal organs

Summary:

Crustaceans (3)

– Dominantly aquatic arthropod

– Some live in moist terrestrial environments

– Extensively specialized appendages

Definition definition:

Plankton (4)

– Passive drifter

– Weak swimmers

– Small, some are microscopic

– Includes larval forms of larger crustaceans

Crustaceans

– Barnacles on whale

Crustaceans

-Cymothea (isopod)

Summary:

copepods

– Important food source in aquatic systems

– Some predatory (can be used to control populations)

– Can be parasitic on fish

What is an example of a copepod that is predatory?

Mesocyclops used to control dengue mosquito