Arthropods Flashcards
TRUE or FALSE: Arthropods are the smallest phylum in the animal kingdom?
False - they are the largest
What groups are encompassed within Arthropods?
Crustaceans (crabs, lobsters, shrimp), Arachnids (spiders, ticks, mites, scorpions), and Insects
(bugs, ants, bees, moths, flies, fleas, mosquitoes)
What are some problems caused by arthropods?
- Annoyance
- toxins/ Venom
- Allergic Reactions
- Invasion of host tissues/ trauma
- Disease/ pathogen transmission
What are the important arthropod groups?
- Arachnids and Insects
What are 2 groups within Arachnids?
Mites and Ticks
What is some important general information about arachnids?
2 distinct body parts – cephalothorax and
abdomen
• 8 legs attached to cephalothorax, no
wings or antennae
• Actively feed on host tissues and fluids at
some stage of their lifecycle
What are the 4 groups within Insects?
- Hemiptera (Bugs)
- Phthiraptera (Lice)
- Siphonaptera (Fleas)
- Diptera (Flies)
What is some important general information about insects
3 distinct body parts – head, thorax, abdomen
• 6 legs, 2 antennae, 2 pairs of wings attached
to thorax
• Actively feed on host tissues and fluids at some
stage of their lifecycle
What are some important characteristics of mites?
- Dorsally flattened
- small < 1mm
- 6 legs as larvae to nymph
- 8 legs as an adult
What are the features of mites that are diagnostically important?
l length of pedicel ( stalk connecting leg to caruncle) and caruncle (cup like sucker)
- Chilicerca (feeding mouthparts)
- Location of anus and anal plate
What are the two types of mites? What are some differences between them?
- Burrowing mites- Short stumpy legs, circular shape, smaller than surface mites. They tunnel into skin.
ex: Demodex - Surface mites- Long distinct legs, generally round to oval shape, larger than burrowing mites, remain on the surface
ex: Otodectes
What is the lifecycle of mites?
Egg -> Larvae-> Nymph -> Adult
How are mites transmitted?
By contact (direct and indirect)
What symptoms/ issues can mites cause?
- No effect to sever dermatitis (mange)
- Hypersensitivities ( allergic reactions)
- Excoriation and secondary bacterial infection.
What are Ticks?
Well-known vectors of human and veterinary pathogens (e.g Lyme, Ehrlichia etc.)
- Most important in veterinary field **
What are some key features of ticks?
- Dorso-ventrally flattened
- Larvae 6 legs, nymph and adults 8 legs
- Not very host specific
- Sexual dimorphism obvious
What are the two types of ticks?
Hard ticks (Ixodidae) and Soft ticks (Argasidae)
What are some important features of Hard ticks?
Mouthparts visible when seen from above
• “Plate” on the back – Scutum
• Found in habitats rich with vertebrate hosts,
moist woodlands, forest edges, hiking trials
• More important (parasitize more people/animals
and more diseases in the US)
What are some important features of Soft ticks?
- Mouthparts invisible when seen from above
- Lack scutum – wrinkled body
• Found in animal burrows, dens. Can survive
hot and dry conditions
• Less common. Species of veterinary
importance are Ornithodorous spp., and
Otobius spp.
What ticks are the most important in veterinary medicine?
Hard ticks and 3 host ticks
What is the lifecycle of 3 host tick?
- ) Adults will feed/ mate on third host
- ) Female will drop off host and oviposit
- ) Eggs will hatch and 6 legged larva will feed on first host.
- ) Larva will leave after feeding and then molt to nymph
- ) 8 legged nymph will feed on second host, then leaves and molts to adult
- ) Cycle repeats
What is the life cycle of the one host tick?
- ) Eggs hatch and 6 legged larva find host.
- ) Larva has 2 molts on host.
- First molt to 8 legged nymph.
- 2nd molt to adult on host - ) Adults mate
- ) Female drops off host and oviposits
- ) cycle repeats
What is the action the tick is doing in this photo?
Questing- Host seeking behavior
What are some issues ticks can cause?
All ticks can cause:
- Anemia
- Dermatitis, alopecia
- Local bacterial infection of bites
Some ticks:
- Paralysis: Salivary toxin of female tick
- Pathogen transmission
- Alpha-gal syndrome (red meat allergy)
What are some general characteristics of lice?
- Dorso-ventrally flattened
- 6 legs
- High host specificity, also site specific
- Divided into two main groups
What are the two types of lice?
Chewing/ biting lice (Mallophaga)
Sucking louse (Anoplura)
What are the key characteristics of Chewing/ biting lice? Sucking louse?
Chewing/ Biting Lice:
- Wider head (wider than thorax)
- Occurs mainly on birds, occasionally on mammals
- Stout mandibles
Sucking Louse:
- Head narrower than thorax
- Nearly every mammal can be infested by sucking louse
- Piercing mouthparts
What is the duration of the lifecycle of lice?
Entire lifecycle (20 – 40 days) on the host
How long can lice live off of the host?
Can live 2-3 weeks off the host but usually less than a week
How are lice transmitted?
Direct or indirect contact – Grooming instruments
When is infection more likely to occur with lice and what are the effects lice can have on the patients?
- Infestation more common in the winter in northern climates – long
hair
What are some key features of fleas?
- Laterally flattened §
- 6 legs
- Not host specific
- Lack wings but strong claws (attachment) and hind legs adapted for jumping
- Chewing mouthpart
What is the diagnostic feature for fleas?
Shape of head and combs
What is the flea lifecycle? What conditions are optimal for growth/ survival of fleas?
Egg -> Larvae (1-3) -> Pupae -> Adult
Conditions: Warm and humid ( 75-90 degrees, 60-85 % humidity)
More Descriptive Life cycle:
- ) Eggs laid on hosts and are dislodged from the coat while shaking, scratching
- ) Development to larvae, pupae (inside cocoon) in the animal resting site.
- ) Larvae feed on flea poop “flea dirt”
- ) Adult hatch from cocoon when the host is nearby
What do flea larvae feed on?
Adult flea poop or “flea dirt”
When do adult fleas hatch from the cocoon?
When host is nearby.
What signs/ symptoms can effect patients with fleas?
- Dermatitis
- Flea bite hypersensitivity (Flea allergy dermatitis, FAD in dogs)
- Anemia (rare, young animals)
What are some pathogens that can be transmitted by fleas?
- Pathogen transmission:
- Plague
- Flea-borne typhus
- Feline parvovirus
- Tapeworms (D. caninum)
- Nematode (A. reconditum)
What is some general information about bugs?
- Dorsoventrally flattened. Some bugs look like lice
- Variable host specificity
– e.g Bed bug can bite both people and pets
- Blood feeders
- Bugs don’t live on people/pets, they bite host only when they need blood meal
- Mostly feed at night, during day hide in crevices
What is the lifecycle of bugs?
Eggs ->Nymph (5 instars (stages) ) -> Adult
- Bloodmeal is needed before each molt.
- Adults can live for up to 1 year and can survive long period without feeding
What are some key characteristics of flies?
§ Important group of animal ectoparasites
§ Most have one pair of wings (adults)
§ Greatly vary in size, colour, food preference and
developmental stage that parasitize animals.
§ Adults feed on blood, saliva, tears, mucous of
hosts
§ Vectors and Intermediate hosts for many
pathogens microparasites
§ Larval stages may cause myiasis (s/c tissue,
respiratory track or GI track
What are the 3 types of flies and what is some general information about each?
- ) Biting fly - Damaging stage is adult fly, blood sucking.
- Scissor like mouthparts - ) Non- biting (nuisance flies)- can cause nuisance and stress.
- Mouthpart has soft, spongy structure called labella and proboscis. - ) Myiasis causing flies- Damage caused by maggots (larvae) that feed on host tissues. Adults are non biting.
ALL CAN TRANSMIT DISEASES
What are some examples of Biting Flies?
- Horsefly
- deer fly
- Horn fly
- Stable fly
- Black fly
- Biting midge
- Sand fly
- mosquitoes
What are some examples of non biting flies (nuisance flies)?
- Face fly
- Head fly
- House fly
What are some examples of myiasis causing flies?
- Blowfly
- Horse bot fly
- Human bot fly
- Nasal bot fly
- Screwworm fly
- Warble fly
What is the lifecycle of biting flies?
- ) Adult flies feed on horse
- ) After each meal, female lays eggs on ground with suitable substrate
- ) Eggs hatch in 12-24 hours to first instar larvae
- ) Larvae mature through three instars to pupae within puparia, then to adults within puparia.
- ) Adults emerge from puparia and can fly within an hour.
Life cycle completes within 12-20 days depending on environmental conditions.
What is the lifecycle of horse bot flies?
- ) Fly lays eggs no hairs, around legs, shoulders, neck and mouth.
- ) Horse injests eggs
- ) Eggs will attach to stomach / intestinal wall and grow into larvae (here they will live for 8-10 months)
- ) Larvae pass out in feces
- ) Larvae mature through three instars. Pupae withing puparia, and then to adults within puparia. This occurs in about 3-10 weeks.
What is the pathogenesis of flies?
- Harassment (common)
- Anemia (rare)
- Dermatitis/local infection
- Hypersensitivity
- Organ-specific damage
- General tissue necrosis
- Pathogen transmission
List the arthropods in order of decreasing host specificity.
Lice
Mites
Fleas
Ticks
Flies
How do you diagnose arthropod parasites?
- Morphology of adult/ larval/ egg stages
- Skin inspection
- Ticks/ flies - easily visible (remove intact organism and look at with disecting microscope)
- Examine third instar larvae of flies- spiracular plate
- Mites- skin scraping- superficial/ deep
- Tissue digestion using 5% KOH (for mites during deep scraping)
What arthropod are these?
Flies
What is this arthropod?
Bug (Specifically bed bug)
What is this arthropod?
Fleas
What is this arthropod? Bonus: What is its scientific name?
Chewing/ Biting Lice
Bonus: Mallophaga
What is this arthropod? Bonus: What is its scientific name?
Sucking Louse
Bonus: Anoplura
What is this arthropod? What subtype is it?
Bonus: What family is it from?
Tick
Subtype: Hard Tick
Family: Ixodidae
What is this arthropod? What subtype is it?
Bonus: What family is it from?
Ticks
Subtype: Soft Ticks
Family: Argasidae
What is this arthropod? What is its subtype? Bonus : Example of one of them.
Mites
Subtype: Burrowing Mite
Example: Demodex
What is this arthropod? What is its subtype? Bonus : Example of one of them.
Mites
Subtype: Surface Mites
Example: Otodectes (Ear mites)
Why are arthropods an important group of ectoparasites?
- Intermediate hosts for other parasites and vectors for micro-parasites
- Very successful and adaptable – high reproductive potential
What are some arthropods that cause allergic reactions?
Bites or stings by lice, bugs, fleas etc
What are some arthropods that cause disease/ pathogen transmission?
Kissing bugs – Chagas disease
Mosquitoes - dog heartworm
Ticks - Lyme, Anaplasmosis, ect
What is the consequences of arthropods that invade host tissue?
- Cause trauma
- Invade the body tissue of the host
- Fly larvae invasion – Myiasis
- Dermatitis, pruritus (itching
How long does it take a mite to go through an entire life cycle? Where does it take place?
- Entire lifecycle completes on the host.
- Length of life cycle varies, few day (Sarcoptes) to weeks
How long can mites last in the environment?
Environmental survival limited (Only some species can survive few weeks outside the host)
What is a consequence of infection of lice?
- Pediculosis – Pruritus, alopecia, excoriation, hair loss, anaemia
Fleas can be intermediate hosts to what ?
Some nematodes
How are bugs transmitted?
Through contact. They live mostly in the environment, in crevices
