Arthropods Flashcards
Mutualism
Two organisms of different species exist in a relationship where each individuals benefit from the activity of the other.
Parasitism
Non-mutual symbiotic relationship between species, where one species, the parasite, benefits at the expense of the other, the hose.
Commensalism
One organism benefits from the other without affecting it.
Definitive Host (DH)
Host in which the parasite reach maturity and reproduces sexually.
Intermediate Host (IH)
A host that harbours the parasite only for a short period, during which usually some developmental stage is completed.
Paratenic Host (PH)
Mechanical host. It is not developing in that host at all. Hitching along for a ride.
Direct Life Cycle
A life cycle in which a parasite is transmitted directly from one host to the next without an intermediate host or vector of another species.
Reservoir host
Can harbour a pathogen indefinitely with no ill effects
Key elements of life cycles
Infection, location, transmission
Most common way of getting into the blood stream
biting vector
Pathogenesis
Mostly relates to where the parasite is (intensity of the infection) i.e. blood stream causing anemia, GI tract causing GI issues
Key elements of transmission
How big is the parasite? How is the parasite getting out of the host?
Issue with water soluble treatments
do not penetrate tissues well. Need lipid soluble treatment
When is a tapeworm harmful?
Hydatid cyst is harmful in the intermediate host
Echinococcosis
Parasitic disease of tapeworms of the Echinococcus type
What are parasitic helminths?
Worms
What are protists (Protozoa)?
Motile unicellular eukaryotic ogranisms. e.g. Giardiasis, Toxoplasmosis, Cryptosporidiosis
What are Nematodes?
Roundworms
What are Trematodes?
Flukes
What are Cestodes?
Tapeworms
What are arthropods?
Invertebrate animal with an exoskeleton (external skeleton), a segmented body and jointed appendages. Crustaceans, insects and arachnids i.e. tick, tsetse fly
Crustacea
Greater than 5 pairs of legs. Often numerous body segments. Many aquatic. Crabs, yabbies, copepods, isopods, and pentastomids. Primarily parasites of marine fish, but some are relevant to vet science.
Pentastomida
*Relevant from a veterinary stand point (nasal cavity in dogs- Linguatula serrata) *Internal parasites of reptiles, birds and mammals *“tongue worms” but nothing to do with the tongue *Previously thought to be allied to mites. *DNA sequencing data indicates that they are modified crustaceans *Internal parasites of respiratory system *Elongate, no appendages *Indirect lifecycle *2 hooks on either side of mouth eggs contain embryo when late respiration cutaneous
Linguatula serrata
“tongue worm” of dog and fox, female up to 8-13 cm, male to 2 cm, tongue shaped, anterior end wider, cuticle with annular striations, eggs contain larvae when laid, eggs passed in nasal discharge or faeces, larvae live in mesenteric lymph nodes of herbivores and occassionally the lung or liver- sheep, cattle, pigs, dog, cat, and man reported infected, when eaten grow to maturity in 6 months, worm doesn’t appear to cause any ill effects but may cause sneezing and a nasal discharge, treatment: surgery, ivermectins
Porocephalus
Aka Tongue worms
How many pairs of legs on insects?
3 pairs of legs
How many pairs of legs on arachnids?
4 pairs of legs
Cuticle (arthropod)
Chitinous (tough) exoskeleton, impervious to many chemicals
What are unique about arthropod’s muscles?
Internal, attached to exoskeleton
What is unique about the circulatory system of an arthropod?
Open circulatory system (with a heart), blood free in haemocoel (a cavity between organs through which blood circulates)
What does arthos and podos mean?
Arthos- joint Podos- foot
Coelomate
Cavity termed haemocoel. Blood is free in this cavity in arthropods.
What is significant about the digestive system of some arthropods from a veterinary standpoint?
Salivary glands- vehicle to act as a vector for other parasites. Saliva into a wound.
What is the nervous system of an arthropod? And why is it relevant to us?
Ganglia or brain surrounding oesophagus, longitudinal nerves with a ganglion in each segment. Important in targeting arthropods for control. Most chemical compounds target the nervous system somehow.
How does an arthropod respirate?
Diffusion of O2 through cuticle (exoskeleton), gills, or tracheal system opening through spiracles (external openings leading to a series of tracheae normally) or stigma(ta). That’s why covering them in oil suffocates them, which is a common treatment.
Copepoda
Not overly relevant to veterinary science Ectoparasites of fish. Free-living copepods act as IH of tapeworms (spirometra) and nematodes (Gnathostoma). Many are important ectoparasites of fishes. Lernea spp. and Argulus foliaceus are pathogenic copepods of aquarium fish.
Ectoparasite
A parasite such as a flea that lives on the outside of a host.
Isopoda
Ectoparasites of marine fish and crustaceans Tongue biters are large isopods found in the mouth of marine fishes. The “leather jacket louse”, Ourozeuktes owenii, is a large bizarre isopod which burrows into the body cavity of its fish host
Indirect Life Cycle
Parasites that infect more than one host species to complete their life cycles are said to have complex or indirect life cycles.
Life cycles of arthropods
Moult: stages called instars (developmental stage of an arthropod between moults) Metamorphoses are common
Obligate parasites (give example too)
Must have a host (fleas)
Facultative parasites (give example too)
Can survive without host (flies)
Permanent parasites (give example too)
On host all the time (lice)
Intermittent parasites (give example too)
Visit host periodically (mosquito)
Pathogenicity of arthropods
May kill host (sheep scab), or cause production loss (body lice in sheep), or irritation (mosquitoes), may act as vectors for viruses, bacteria or other parasites (i.e. flies acting as mechanical vector landing on faeces and then somewhere else)
What are the three chemical controls of arthropods?
- Repellents (DEET, citronella)- does not kill, but keeps them away 2. Chemicals acting on the nervous system (DDT (will not encounter anymore because it does not break down in the environment)), chlorinated hydrocarbons, organophosphates, carbamates, etc.) 3. Growth regulators- do not directly kill but effective as a supplement to something that directly kills (i.e. flea control- combo of a chemical that kills and an insect hormone (renders them infertile if they survive the chemical that kills them))
How do organophosphates work? (name two examples)
*Inhibit acetylcholine esterase, binding reversible and cause paralysis. *Persistence- Variable but relatively short (24 h- 12 weeks), broken down in environment, non-cumulative *Toxicity to vertebrates- parasympathomimetic stimulation antidote- atropine *Administration- topical or oral *i.e. malathion- wash for flea control; diazinon- jetting sheep for blowfly control
How do carbamates work? (name example too)
*Similar mode of action to organophosphates. *Persistent 4-6 weeks *i.e. carbaryl power or spray for fleas (flea collars), propoxur
How do Formamidines work? (name example too)
Inhibit mono-amine oxidase i.e. amitraz- used for cattle ticks and demodectic mange e.g. Amitraz used for cattle ticks and demodectic mange
How do Pyrethroids work? (name two examples)
*Pyrethrin derived from Chrysanthemum flowers persists for only 24 hours, synthetic pyrethroids- more potent, persist for 7-14 days, act on sodium channels. *Administration- topical *Toxicity to vertebrates- very low except fish i.e. Permethrin- scabies on humans, deltamethrin- lice in sheep (backline) *(anything that ends in -thrin)
How do Macrocyclic lactones work? (name two examples)
*Secreted by soil-inhabiting Streptomyces spp. Block neurotransmitter to cause paralysis. Act on glutamate-gated chloride channels *Major groups: Avermectins (i.e. ivermectin) and Milbemycins (i.e. moxidectin) *Extremely potent. *Administration- topical, parenteral, oral Highly effective against nematodes and arthropods
How do neo-nicotinoids work? (name two examples)
*Attack nicotine receptors. Mimic nicotine (important neurotransmitter). Non-toxic to vertebrates. *New group, synthetic, block receptors, non-toxic *Administration: topical *Translocated in skin *i.e. flea control–> imidacloprid- blocks nicotinic receptors (Advantage), fibronil (blocks GABA receptors- Frontline)
How do growth regulators work? (name three examples)
*Analogues of insect growth hormones, interfere with growth/ moulting/ egg laying, toxicity- low *administration- oral or topical, does not kill arthropods immediately (used in conjunction with something that does is often effective) i.e. methoprene (flea), cyromazine (blow flies), fluazuron (cattle tick)
Linguatula serrata life cycle pathway
Predator/ prey pathway. Eggs are shed in the faeces, picked up by an IH, dormant stage in the tissues through several moults, into a more mature larval stage
What arthropod is this?
What are the clinical signs?
How do you diagnose?
What is the treatment?
Linguatula serrata
Find eggs in faeces
Ivermectin
Pentastomida Life Cycle
Insecta features
* 3 pairs of legs
* head, thorax, and abdomen
* antennae
* +/- wings
Diptera
flies, midges, mosquitoes
siphonaptera
fleas
Phthiraptera
lice
Nematocera
Diptera (two wings)
midges, mosquitoes
* small flies (up to 3 mm)
* antennae long and slender
* larvae and/or pupae are aquatic
* females parasitic- need a blood meal
* intermittent parasites
* often not host specific
Brachycera
Diptera
March or horse flies
Cyclorrhapha
Diptera
“true” flies
Ceratopogonidae
Nematocera, Diptera
Biting midges, “sand flies” in Australia
Simuliidae
Nematocera, Diptera
black flies
Psychodidae
Nematocera, Diptera
sandflies
Culicidae
Nematocera, diptera
Mosquitoes
Nematocera effects on the host
Irritation due to bites
Glood loss
vectors for:
*viruses (bluetongue, ephemeral fever, etc.)
*Bacteria (mechanical transmission anthrax)
*protozoa (malaria, leishmaniasis)
*nematodes (Dirofilaria, onchocerca)
Nematocera- family, main genus, identification, and life cycle, and mouth part names
Family: Ceratopogonidae
Main genus: Culicoides
Identification: spotted wings
Life cycle: larvae develop in water, mud, sand or dung
mouth parts: they have palps and chelicerae (like scissors)- they use to bite
Nematocera “maritime species”
C. immaculatus, C. marmoratus
* breed in saline waters, mangroves
*crepuscular
* not host specific
*human nuisance
Nematocera “native species”
C. marksi breed in fresh water (pools of water), feed on marsupials and stock, abundant in wet season in northern Aus, crepuscular, feeds on legs and belly of cattle, transmit the nematode (Onchocera gibsoni)
Nematocera “introduced species”
C. brevitarsis, C. wadai
Breed in cattle dung
crepuscular
bite on dorsal midline
Significance- cause “Queensland itch” in horses, transmit bluetongue
Culicoides brevitarsis
Nematocera, “introduced species”
Queensland itch of horses
* lesions around tail, rump, back, poll, ears
* hypersensitivity to bites
* Stable horses
* wide distribution, inefficient vector
* use repellents
What is the classification based on these antennae?
Nematocera
Brachycera
Cyclorrhapha
Culicoides wadai
Limited distribution, effective vector
Blackflies- nematocera: family? genera? Life cycle? Effect on hosts? Major pests in Aus?
Family: Simuliidae
Genera: Simulium, Austrosimulium
Life cycle: aquatic, occur along rivers, larvae carnivorous, eggs survive in sand, develop following flood
Effects on hosts: severe irritation
Major pests in AUS: A. pestilens
in Africa: S. damnosum
Transmit Onchocera gutturosa of cattle and O. volvulus of man (in Africa)
sand fly- family? genus? identification? Importance? In Aus?
Classification: Insecta, Diptera, Nematocera
Family- psychodidae
Genus- Phlebotomum
Identification: hairy wings
Importance: vectors of protozoan disease leishmaniasis
in Aus, species all reptile feeders
Mosquitoes- family? genera? life cycle? Effect on host?
Nematocera
Family: Culicidae
Genera: Aedes, Anopheles, Culex
Life cycle: larvae aquatic, females feed on blood, male non-parasitic, diurnal, nocturnal or crepuscular
Cause: irritation, blood loss
Act as vectors**
Viruses: Yellow fever, equine encephalitis, dengue, myxoma, Ross River, Barmah Forest, Murray Valley Encephalitis
Protozoa: malaria
Nematodes: Dirofilaria immitis
Control: remove breeding sites, repellents
Tabanids, horse flies, and march flies- family? genus? life cycle? effect on host? Vectors for?
Brachycera
Family- Tabanidae
Genus- Tabanus
Life cycle: very large, slow flies, short antennae, very painful bite, larval stages aquatic, coasts and forests along creeks
Effects on host: irritation, blood loss
Vectors for trypanosomes, anthrax, some nematodes
Family: Oestridae
(Order: diptera “flies”, sub-order: cyclorrhapha- short antenna + arista)
What are they? What are the features?
Bot flies
Features: - large flies (may resemble bees)
- vestigial mouth parts- cannot feed (sucking fluids or sucking blood)
- lay eggs or are viviparous
- LARVAE are PARASITIC
- Larvae are endoparasites
- three larval stages in host
- pupate on ground
Gasterophilus
(Order: diptera “flies”, sub-order: cyclorrhapha- short antenna + arista)
What are they? Name a few Australian ones.
Horse bots
Species in Australia:
G. intestinalis- common bot
G. nasalis- throat bot
G. haemorrhoidalis- nose bot (rare)
Gasterophilus- Characteristics of main sub-order? And of Australian species?
Flies active in summer, only live for a few days, can lay many eggs
G. intestinalis- eggs yellow, anywhere on front of body, hatch when licked
G. nasalis- eggs pale, laid between mandibles, hatch spontaneously
G. haemorrhoidalis- eggs black, laid around lips, hatch spontaneously
Gasterophilus- horse bots
Gasterophilus- horse bots
Gasterophilus- horse bots
Gasterophilus- horse bots life cycle
- First instar: migrates through mouth and gums
- Second instar: attaches in stomach
Third instar: in stomach
Gasterophilus- horse bots
Gasterophilus- horse bots: life cycle?
Remain in horse for 9-12 months. Passed out in faeces. Pupate in soil. (Larvae of G. intestinalis- red, occur in stomach, 2 rows of spines; Larve of G. nasalis- yellow, occur in duodenum, 1 row of spines)
Treatment and control of Gasterophilus- horse bots?
Tx: organophosphates (dichlorvos, trichlorphon); macrocyclic lactones (ivermectin, moxidectin)
Control: treat in winter when flies are absent; washing or grooming to remove eggs of little value
Oestrus ovis
(Class: insecta; order: Diptera; family: Oestridae)
Nasal bot of sheep and goats (second and third instars in nasal cavity of sheep and goats)
- fly viviparous
- lays larvae on external nares
- larva crawls into nasal cavity
- all larval stages found in nasal cavity
- third instar sneezed out
- pupae develop in soil
- flies active in summer
Oestrus ovis- nasal bot of sheep and goats
Oestrus ovis- nasal bot of sheep and goats
What is the effect of the nasal bot on sheep and goats? What is the treatment?
Agitates sheep when laying eggs, chronic nasal discharge, predisposes to pneumonia
Tx: organophosphates; macrocyclic lactones; trematocides (rafoxanide, closantel)
Hypoderma- warble flies of cattle
Hypoderma
Class: insecta
Order: Diptera
Family: Oestridae
Warble flies of cattle
i.e. Hypoderma bovis, Hypoderma lineatum. Common in Europe, Asia, and North America. Not present in Australia.
Life cycle of hypoderma
Lay eggs on the leg of cattle, burrow into skin- migrate through tissues along spinal column up to the base of the neck, then they migrate down the dorsal line of the animal, stick spiracle out of animal- feed on blood and flesh, moult, push out through the wound drop off into the ground and they pupate. They can be in the animal for 6 months.
Dermatobia hominis
Another type of bot fly. Tropical warble fly. South America. Uses mosquitoes, ticks as transport hosts, affects any vertebrates including man.
Tracheomyia macropi
In trachea of red kangaroo
Cephenomyia spp.
In pharynx of deer
Cephalopina titillator
Nasal bot of camels
Musca domestica
Class: insecta
Order: Diptera
Family: Muscidae
House fly. Involved in the mechanical transmission of pathogens; IH of nematodes and cestodes
Life cycle of musca domestica?
Musca vestustissima
Class: insecta
Order: Diptera
Family: Muscidae
Bush fly. Breed in cattle dung. Over winter in northern Australia. Cause similar problems to M. domestica.
what is this? What is the effect on hosts?
Stomoxys calcitrans- the stable fly.
Both sexes feed on blood. Bite any mammals. Horses and dogs commonly affected.
Haematobia exigua- the buffalo fly
- Small grey fly
- rigid, biting mouthparts
- introduced from SE Asia
- closely related to: H. irritans, the “horn fly” of Europe & America; H. minuta, in southern Africa
- feed on cattle, buffalo, horses, and dogs
Haematobia exigua- the buffalo fly life cycle
- flies remain on host
- die in 1-2 days away from host
- leave host to lay eggs
- breed in cow dung
- emerging flies have 1-2 hours to find a host
- leave host to lay eggs
- breed in cow dung
- emerging flies have 1-2 hours to find host
- need a blood meal to breed
- adults live for 10-20 days
- need temperatures > 20 C
- life cycle takes 7-11 days
Epi of Haematobia exigua?
Spread by travelling cattle, can travel up to 7 km on prevailing winds, heavier infestations on bulls, geographical distribution limited by temperature and moisture
Haematobia exigua- effects on host? Control?
- bites are painful
- cattle rub to relieve irritation
- 2000-3000 flies a heavy infestation
- loss of condition or delay in fattening
- milk production drop
- vector of Trypanosoma evansi & of nematode Stephanofilaria sp.
CONTROL: fly traps, ear tags impregnated with insecticides, insecticides (ivermectin) which persists in dung, dung beetles
Hippoboscidae
Class: insecta
Order: Diptera
Family: Hippoboscidae
Louse flies or hippoboscids
- exclusively parasitic (blood feeders)
- feet with strong claws
- females viviparous
- larvae pupate immediately
Melophagus ovinus- what is it? Features? Effects on host?
The sheep ked
No wings, lives in wool, pupal case attached to wool, live 4-5 months
Effects on host: blood feeders, cause anaemia, stain wool (“ticky wool”), transmit Trypanosoma (protozoan)
Melophagus ovinus- the sheep ked
Family Calliphoridae- what are they? How are they important? Major diseases?
Blow flies, flesh flies, and screw worm flies.
Important environmentally, breed in decaying organic matter, adults feed on decaying organic, material or nectar, facultative parasites (usually).
Major disease: blow fly strike of sheep (cutaneous myiasis); screw worm fly (exotic)
Green species- primary, secondary, or tertiary? Native or introduced?
Primary- initiate blowfly strike (sheep)
Lucilia cuprina- introduced - 90% of strikes
Lucilia sericata- introduced- urban areas
Secondary species (wound is already started):
Chrysomyma rufifacies- native- sometimes primary
Chrysomya varipes- native
Black species- primary, secondary, or tertiary? Native or introduced?
Tertiary
Ophyra spp. - native
Brown species- primary, secondary, or tertiary? Native or introduced?
Secondary species
Calliphora stygia- native- sometimes primary
Calliphora augur- native- sometimes primary
Blue species- primary, secondary, or tertiary? Native or introduced?
Tertiary
Calliphoa vicina- introduced- urban areas
Flesh flies-
primary, secondary, or tertiary? Native or introduced?
Tertiary
Sarcophaga spp.- native
What is this? Features/ importance?
Lucilia cuprina
Responsible for >90% of strikes; almost obligate parasite; can breed in carcases but outcompeted.
Lucilia sericata
Lucilia cuprina- life cycle?
Eggs laid in batches in fleece; laid in afternoon; hatch at night; first instar needs protein meal; cannot penetrate skin; second instar penetrates skin & feeds on tissues
Third instar matures by 2-19 days; drops to ground at night; burrows into soil; pupates (3-7 days); overwinters as pupa
Entire life cycle 17 days (in summer)
** ONLY MATE ONCE**
Emerging females need protein meal to produce eggs, most strikes are “covert”- not an expansive disease- maybe a small fever that you wouldnt even notice. Only 10% of the time you have serious problems. This is when Secondary flies can invade and extend the wound.
Lucilia cuprina- clinical signs?
Day 1-2 sheep irritated
day 3 temperature rise
day 4 maggots drop, smell
day 6 temperature falls
healing slow but complete
In bad year, mortalities can be up to 30%
Blow fly strike pathogenesis?
Normal sheep are not struck by flies (normal = clean, dry fleece)
Need olfactory stimulus to attract flies
Need proteinaceous exudate on skin for first larval instars
Primarily you see breach strike (legs and base of tail). You can see body strike, poll strike (rams), pizzle strike (rams & wethers).
Breech strike
Most common form of strike, soiling of fleece by urine and faeces, scouring due to nematodes (can reduce prevalence 10 fold)- diarrhea provides initial meal, wrinkles predispose to strike.
Body strike
- Preceded by “fleece rot” or dermatitis
- Prolonged wetting of skin– keratin lifts– protein exudes
- Pseudomonas spp. proliferate and provide olfactory stimulus also stain wool
- body conformation (‘sway back’) and wrinkles predispose to strike
- fleece characters (wax content) important
Seasonal prevalence of blow fly strike
Fly numbers determined by temperature and rainfall, flies overwinter as pupa, emerge in spring. Usually 3 generations in spring, summer too dry for eggs and first instars, autumn moister and cooler- 2 generations. Pattern of infection generally bimodal. If summer is wet, flies active all summer.
What are ways to render sheep less susceptible to blow fly strike?
Crutching (shaving or surgically removing flesh around there), correct tail docking, removal of conformational faults, breed for sheep with suitable fleece characteristics, Mules Operation most successful method
How do you reduce fly number?
-Treat all strikes seen earlyin season (covert strikes)
- burn or deeply bury carrion
- fly traps- drums with meat laced with insecticide
- genetic manipulation- sterile male methods
- vaccines- currently under investigation
- chemicals- organophosphates (resistance widespread) & growth regulators (cyromazine; Vetrazin)
What is this? What do the larva feed on?
Chrysomya rufifacies- common name: the hairy maggot blowlfly.
Larva feed on other maggots.
Chrysomya rufifacies- common name: the hairy maggot blowlfly.
What is this? And common name?
Chrysomya bezziana- old world screw worm fly. Common name: blue blowfly. Not present in Aus.
What is this? Where is the pupal stage?
Chrysomya bezziana. Pupal stage in soil.
Chrysomya bezziana
Chrysomya bessiana. Likely will kill them. If it does not kill them substantial scars afterward. Yellow spots are the larvae.
Where do biting lice lay their eggs?
In the skin.
Are lice effective parasites? Why or why not?
Not very effective parasites because most are host specific and obligate parasites, so not really moving from host to host.
Features of arachnids. Examples of arachnids.
4 pairs of legs, 3 pairs of legs in larva, no antennae, no wings, body divided into 2 parts (gnathosoma (relates to chewing)- capitulum), idiosoma (the rest of the body).
* ticks, mites, spiders, scorpions
Features of ticks
Obligate parasites; need blood meals; most of life cycle is spent off host; variable host specificity. Ambush parasites, climb on top of grass and wait for host to come by.
Chelicerae- scissors- cut wound open
Hypostoma- feeding apparatus- sucks the blood (backward feeding hooks)
Palp- 2 palps- basically feelers (shape becomes important in recognizing what kind of tick)
Basis capituli- main part of head
* eyes are between 1st and 2nd legs- not on main part of head
Tick Life Cycle
No pupae stage.
Larva (with 6 legs)- also like a tiny adult just with 6 legs
Nymph (with 8 legs)- just like small adults
Male and female (8 legs)
Multihost life cycle
Number of times a tick goes back to a host to feed. 3 host stage- at multiple times in its lifecycle; or a 2 host- might mean they feed during nymph phase and adult but not larva.
Pathogenic effects of ticks
Blood loss (tick can take 5mL of blood), irritiation, hypersensitivity, damage hide, reduce growth rate of host, produce toxins (paralysis), transmit protozoans
Soft ticks
Family Argasidae
* no scutum, mouthparts underneath, rapid feeders (hours)
Hard ticks
Family Ixodidae
Scutum present, mouth parts anterior, slow feeders
Fowl tick
Argas persicus
“tampan” ticks
Ornithodoros moubata
O. gurneyi
Spinose ear tick
Otobius megnini
Argas persicus features
Reddish ticks, mouthparts concealed, distinct patterened margin to body
Life cycle of argas persicus
Eggs laid in cracks
hatch in 3 weeks
larvae feed for 5-10 days
moult in crevices
nymphs feed in 2 hours
nymph and adult nocturnal
larvae survive for 3 months without food
adults survive for 3-5 years without food
Control/ treatment
Organophosphate spray
Kerosene emulsion
Effect of Argas persicus on host
Anaemia, irritation, reduce egg production, paralysis caused by larvae, transmit Borrelia anserina (tick fever) and Aegyptianella pullorum
“Tampan ticks”
Ornithodoros
What tampan tick is in Australia?
O. gurneyi
Characteristics of O. gurneyi
live in sand, feed on any host species, cause painful bites, transmit Q fever
Characteristics of Otobius megnini (spinose ear tick)
in North America, Africa, adults free living, larva and nymph live in ear, horses cattle, dogs. Found recently in WA.
Genus Ixodes features
Long palps, anal groove in front of anus.
22 species in Australia
“native” ticks
What kind of Ixodes cause paralysis?
I. holocyclus and I. cornuatus
Which Ixodes is a vector of lyme disease (Borrelia spp. bacteria)?
I. dammini
Ixodes holocylcus Life cycle
the paralysis tick
3 host tick, on native mammals, life cycle takes 18 months, larvae and adults in spring, nymphs mainly in autumn, males rarely found on host
Ixodes holocyclus effect on host
the paralysis tick
* all stages cause irritation & paralysis
* sheep, dogs, and cats most susceptible: 1 female tick will kill a dog
* calves & foals also susceptible: 4 female ticks can kill a calf
* can affect humans (homophilic tick)
* females engorge for up to 21 days
* signs develop on day 5-6
* ascending motor paralysis
* intense vasoconstriction
* die from paralysis of respiratory muscles
* native & domestic animals can development immunity
Treatment of Ixodes holocyclus
Find and remove tick, acaricidal wash, hyperimmune serum (after you remove tick, you need to administer- this will coat the toxin and neutralize it), paralysis.
Effect depends on prior exposure to the toxin and number of ticks feeding on them. Ascending motor paralysis- starting at hind limbs.
Ixodes holocyclus geographical distribution
Eastern Australia and Tasmania
Cattle tick
Boophilus microplus
Features of boophilus microplus
cattle tick
* short palps and ridges, pale legs, anal groove behind anus, (difficult to see), engorged femal has “waist”
Geographic distribution of Boophilus microplus
Northern Australia
Boophilus microplus life cycle
Host specific but occurs occasionally on horses, sheep, dogs & pigs.
* 1 host tick
* life cycle takes 22 days
* eggs hatch
* “seed ticks” climb up grass
* attach to passing cattle
* larvae and nymph remain on host
** feed in adult stage (odd tick in that) usually ticks feed in between lifecycles because they need the energy to grow**
* female ticks drop off after 18-37 days, most on day 22
* drop off mainly in early morning
Boophilus microplus effect on host
Irritation- ticks removed by grooming, damage to hides, anaemia- each tick takes 1-5 mL of blood, anorexia (reduced appetite), reduced growth rate and milk production, transmit protozoans (Babesia, Anaplasma, Theileria)
Boophilus microplus favorable climates
* Ticks controlled by temperature and humidity.
* in general summers are too hot, winters are too cold
* autumn is ideal time. Spring is a little too cool
* winter suppresses tick development
* tick numbers increase in wet season (in dry tropics)
* wet tropics- temp never limiting, ticks all year round, rain in all months
Boophilus microplus dispersal & survival (control)
* larvae accumulate around site of egg mass
* can migrate short distances (<1 m)
* can be blown up to 30 m
* cattle avoid heavily infested areas
* can “spell” paddocks to control ticks (leave the paddock alone, so they starve)
* in summer 50% live 2 weeks, 10% live 4 weeks, can be up to 11 weeks in cool weather
How do you treat Boophilus microplus?
Macrocytic lactones (topically or orally) started in 1985. Prior to that ticks continually developed resistance to all compounds.
What kind of cattle is most resistant?
Zebu Cattle.
Immune system attacks the tick and they drop off. Acquired immunity develops in all breeds.
What is resistance exactly?
You are selecting for the organism that can survive the chemical basically.
Vaccine against tick gut protein- 70% effective (Boophilus microplus vaccine)
Tick ingests blood and with the blood immune cells. Produce a response against the gut protein. When it ingests the blood, all of the immune cells are programmed. Causes loss of gut lining and haemorrhages- kills the tick.
2 vaccinations.
Do not use by itself.
Haemaphysalis characteristics
What is the main species?
Tick on horses and dogs and sometimes on cattle.
Anal groove behind anus
Lateral projection on palps- more fleshy.
Haemaphysalis longicornia- the “bush tick”
H. longicornis characteristics
* 3 host tick (gets on feeds, drops off, in between growing nymph, larvae, and adult)
* occurs in eastern Aus, eastern Vic
* causes anaemia and hide damage
* vector of Babesia gibsoni of dogs
Rhipicephalus chacteristics. What is the main species? Characteristics. Where are they mainly found?
Basis caputili projects, forked first coxa, anal groove behind anus.
R. sanuineus- “brown dog tick”
* common in tropical countries
*anaemia and irritation
*vector of Babesia canis of dogs
** Northern Australia**
Aponomma & Amblyomma
Common in wildlife.
Pretty ticks- very colorful.
Ixodes holocyclus morphology
Long palps
Spiracle mid body
No waist when engorged (haemophisalis- waist when engorged)
Otobius megnini
Where? What are they called? Hosts? Control? Family?
Found in WA. Sheep, cats. “Spinose ear tick”
Family: Argasidae.
Flea control with high concentration of macrocytic lactone. Or fipronil spray.
Mites: Class and Order
Arachnida
Order: Acarina
Characteristics of mites (general)
Abundant, free living
Lack rows of teeth on hypostome
Have capitulum with palps and chelicerae
Can be: intermittent parasites (obligate, have to have a blood feed but spend a lot of time in the environment)- some exceptions
* in nests or burrows or permanent parasites
* can be on skin, in ears, or resp. system
Effect on host: mites
Blood loss, irritation, hair loss, vectors
Life cycle: mites
Egg, larva (with 6 legs), nymphs (proto, deuto, trito), adults
Mesostigmata (sub-order, order: acarina, class: arachnida)
Gamasid mites. Spiracles between coxae 3 & 4 (plate that sits over top of the leg)
Legs at anterior end of body
Many free living
Prostigmata (sub-order)
trombidiform mites. Spiracles on capitulum (absent in some)
Feather like setae
Astigmata (sub order)
Front pairs of legs separated from back pairs
Mange mites
No spiracles, respiration through body wall
Dermanyssus gallinae
Class: Arachnida, Order Acarina, Sub order Mesostigmata
“The red mite of poultry”
* Triangular anal plate
* Parasite of birds and mammals
* life cycle: eggs, larva, 2 nymphs
* eggs laid in crevices
* life cycle 7 days
* nocturnal
* could control with spelling (can’t do with argus)
* blood feeders
Dermanyssus gallinae effect on host
Anaemia, irritation, transmit Borrelia anserina (blood infection, some form of fever)
Ornithonyssus spp. Name two
O. bursa and O. sylviarun
Sub order: Mesostigmata
* Cause severe anaemia, reduced egg production
* Common on wild birds
* found in bird nests
* referred to as “Starling lice”
* feed on birds while in nest
* some on birds all the time
* blood feeders
* NOT host specific***
(Narrow anal plate)- hairer than Dermanyssus gallinae
Pneumonyssoides caninum
Nasal mite of the dog
sub order: mesostigmata
Raillietia auris
Ear mite of cattle
Mesostigmata
Ophionyssus natricis
Snake mite
Sub order: Mesostigmata
Sternostoma tracheacolum
Canary lung mite
Sub order: Mesostigmata
Prostigmata (sub order) features and genera
Features: stigma on capitulum, feather-like setae
Genera: Trombicula, Demodex, Psorergates, Cheyletiella
Trombicula (characteristics, what do they transmit, where on ex)
Family: Trombiculidae
Sub order: Prostigmata
* central hair shaft, some spines coming off
Chiggers, harvest mites
“trombiculids”
Only larvae are parasitic
Attach in clusters
Often yellow or orange
Transmit scrub typhus (Rickettsia australis)
T. sarcina causes “black soil itch in QLD”
Demodex canis
Sub order: Prostigmata
Vermiform (worm like)
Legs very short at the front of the body
Adapted to live inside hair follicles
Feed on cytoplasm
Permanent parasites- always on the host- transmitted through contact or suckling
HOST SPECIFIC
Life cycle: egg, 2 nymphs, adults. All stages in hair follicles.
Demodectic mange effect on host
* All dogs infected (not zoonotic)- most unaffected, if properly function immune system
* only some develop disease
* short haired dogs with Cell Mediated Immunity (CMI) deficiency
Mainly 6-10 months of age
Predilection sites eyes, ears, muzzle
Secondary infection with Staph. albus
* Disease can be localized or generalized. Squamous or pustular (secondary infection)
Infection of follicles leads to hair loss & hyperkeratosis
How do you diagnose and treat Demodectic mange?
Diagnosis: deep skin scraping
Treatment: amitraz, ivermectin, or **moxidectin- lipid soluble compound, will penetrate into the hair follicles much better- topical** or avermectin, can be difficult to treat
D. phylloides
Pig. Lesions mainly on head.
Sub order: Prostigmata
D. bovis
Cattle- damages hide.
D. ovis, D. caprae, D. equi
Sheep, goats, horse. Rare.
D. folliculorum
Sub order: Prostigmata
Mites of man
*Prevalance 50%
* Common in blackheads
* base of eyelashes
Psorergates ovis
Sub order: Prostigmata
The sheep itch mite (very similiar to damiliar ovis- spreads very quickly, whereas Psorergates does not)
* Features: affects sheep in Australia, Africa, N. & S. America
*Tiny mite
* Lives in superficial layers of dermis
* life cycle: egg, larva, 3 nymphs, adults
* 5 week life cycle
* Transmission: contact (suckling, shearing)
* Predilection sites: sides, between hip and shoulder near mid-line
* Seasonal occurrence: most abundant in winter
* effect on host: hypersensitivity causes irritation, rubbing, “pulled wool,” not all sheep affected, spreads slowly in mob
Diagnosis: skin scraping
Treatment: non, amitraz, OPs, ivermectin, will not eliminate mite. Since they spread slowly. louse control, standard back treatment will likely control it. Likely only treat affected animals.
Genus Cheyletiella. 3 Species. Effect on host.
Features
Sub order: prostigmata
C. parasitivorax - rabbits
C. yasguri- dogs
C. blakei- cats
Effect on host: mild mange, often around head, bites humans
Features: claw on palp.
Astigmata (sub order)
Mange mites
Features: front pairs of legs well separated from back pairs
Families: Sarcoptidae and Psoroptidae
Sarcoptidae (family) Sub- order: Astigmata. Features? Generas (4)?
Rear legs very short, burrow in upper layers of skin
Genera: Sarcoptes, Notoedres, Trixacarus, Cnemidocoptes
Psoroptidae (family) Sub order Astigmata. Features? Genera (3)?
Rear legs project
Tissue fluid feeders
Genera: Psoroptes, Otodectes, Chorioptes
Sarcoptes scabiei- features? life cycle?
Sub order Astigmata, family: sarcoptidae
Features: triangular scales on dorsum (on back, even visible on histo slides), wide host range, strains on specific hosts (e.g. var. canis), can survive but not reproduce on hosts
Life cycle:
* lives in supf. layers of skin
lay eggs in tunnel (beneath the skin)
larva and 2 nymphal stages
life cycle 10-17 days off host
mites survive for few days off host
transmission by contract
Sarcoptes scabiei pathogenesis
Burrowing mites cause irritation
Intense pruritis (itching)
Hyperkeratosis
Alopecia
Lesions begin on face, extend over body
secondary infection, pustules, self inflicted trauma
* hypersensitivity
Dog mites can cause lesions on humans and some variety on dogs and foxes
Sarcoptes scabiei diagnosis? Treatment?
Skin scrapings, can be difficult to find mites
Treatment: most insecticides. cannot do oral treatment because they are not feeding on blood.
Sarcoptid genera (2 others)
Tixacarus caviae- sarcoptid mite of guinea pigs
Notoedres cati- mainly on cats and rabits
(sub order Astigmata)
Cnemidocoptes (species- 3)
Sarcoptid mites of birds
C. gallinae- in feathers, depluming mite of poultry
C. mutans- on legs of chickens “scaly leg”
C. pili- on beak and legs of psittacines
Family Psoroptidae (sub order Astigmata)- features? Genera?
Features: posterior legs long, tissue fluid feeders- cause scabs
Genera:
* Otodectes- ear mites of cats and dogs
* Psoroptes- mites of ruminants, horses, jointed pedicels (fleshy part of the leg)
* Chorioptes- mites of ruminants, horses simple pedicels
Otodectes cynotis (family: Psoroptidae, sub order Astigmata)
Common ear mite of dogs and cats, also occurs in foxes and rabbits
Causes scabs in external ear canal, hosts shake heads and rub ears
Transmitted by contact, often while suckling
Diagnosis: with otoscope, unreliable examine exudate under microscope
Treatment: oral or tropical insecticides
** cannot give macrocytic lactones to border collies, for example**
Family: Psoroptidae
Genus Psoroptes
Psoroptes ovis
Features: segmented pedicels
“sheep scab”
* live under scabs
* feed on tissue fluids, cause serous exudate
* life cycle 9-10 days
* high biotic potential
* irritation, scabs, hypersensitivity
* Starts on shoulders and back, spreads over whole body
* In latent cases can occur in ears, inguinal folds, inter-digital spaces
* Most abundant in cool weather
* Can have emaciation & high mortality
* eradicated in Australia
* Prominent when fleece is long and they are protected (same we see with lice*
Psoroptes cuniculi
(Sub order: Astigmata, Family: Psoroptidae, Genus: Psoroptes)
Ear mite
Hosts: rabbit, horse, goat, alpaca
Causes ear mange- may spread onto face
Common in lab rabbits
Causes irritation, shaking of head
Chorioptes (genus)
Family: Psoroptidae
Features: simple pedicels
Chorioptes bovis- affect rams in horns, or scrotum
* sit under scabs, difficult to get access to- topical or oral- that will penetrate scab
* chorioptic mange
* In cattle, sheep, goats, horses
* occurs mainly on legs, belly
* commonly seen in housed sheep and cattle
* referred to as “barn itch” can cause scrotal mange in rams
Which larvae have 2 rows of spines which are slightly longer and dark?
Gasterophilus intestinalis
What traits do Gasterophilus intestinalis larvae have?
2 rows of spines, slightly longer, darker
Which larvae have 1 row of spines that are lighter?
Gasterophilus nasalis
Explain characteristics of Gasterophilus nasalis larvae
Lighter and one row of spines
Which larvae have smaller spines only on the ventral side and distinct hooks?
Gasterophilus haemorrhoidalis
Explain the larvae of the Gasterophilus haemorrhoidalis
Shorter spines only on the ventral side, distinct hooks, darker
