Phylum Arthropoda, Class Arachnida, Order Metastigmata Flashcards
What is the importance of Metastigmata?
ticks are blood sucking arthropods found everywhere. Infect mammals, birds, reptiles and amphibians.
Host specificity: some ticks feed on a wide range of hosts, others are more selective and host specific.
May starve for many months/years
have a direct pathogenic effect on the host which can induce paralysis, severe toxicosis, irritation, allergy, blood loss.
Ticks transmit a greater variety of pathogenic microorganisms.
What are the 2 major families of Metastigmata?
- Ixodidae aka Hard ticks
- Argasidae aka soft ticks
The scutum of hard ticks is present in all stages (males have it completely covering the idiosoma, females only have small anterior portion), is not present in soft ticks
The gnathosoma in hard ticks is anteriorly and terminal whereas in soft ticks it is sub-terminal and hidden by idiosoma.
What is the morphology of Ixodid ‘hard’ ticks?
Relatively large
Body of the unfed ticks is DV flattened
The gnathosoma is located anteriorly and consists of 2 parts
- Basis capituli (BC) and mouth parts.
The mouthparts include;
- 1 hypostome - backwardly directed teeth
2 chelicercae - contain teeth used to cut the skin
- 2 palps - sensory organ made up of 4 segments
The idiosoma contains a dorsal shield / plate called scutum
- Males - covers the entire dorsal surface
- Females, nymphs and larvae - covers 1/3 of the idiosoma
Eyes (if present) are located on the scutum at the 2nd pair of legs
On the ventral side of the idiosoma - contains 4 pairs of legs in adults and nymphs, 3 pairs in larvae.
The first segment of the legs is known as the coxa
The anus is located medially behind the 4th pair of legs
- Anal groove is either in front of the anus (ixodes) or behind the anus for other species.
Festoons –> uniform rectangular formations seen on some species, posterior margin of the body
Stigmata –> respiratory openings that are psoitioned behind the coxae of the 4th pair of legs and are surrounded by stigmatal plate.
Some species contain ventral plates / shields (males only) which are important for identification
What are the morphological stages of the male, female and larvae?
Male –> dorsal scutum which covers most of the dorsal surface, due to this, it restricts the amount of blood it can ingest and results in the males being smaller than the females.
Females - dorsal scutum covers only the anterior region of the dorsal surface - this allows for engorgement
Larvae - contain three pairs of legs
What are the morphological features of the genus Ixodes?
The anal groove is in the ANTERIOR position (in front of the anus)
Mouthparts are longer than the Basis capituli
7 ventral shields
3 host ticks
What is the most important species from Genus Ioxdes in Australia?
Ixodes Holocyclus –> paralysis tick. 3 host tick
ANAL GROOVE POSTERIOR WITH LONG MOUTHPARTS (shorter BC)
What are the general features from the Genus Ambylomma?
Mouthparts are longer the basis capituli
The second segments of the palps are twice as long as the 3rd segment
Males do not contain ventral shields
They contain a scutum ornate (decorations)
What is the most important species of Genus Ambylomma in Australia?
Amblyomma triguttatum –> ornate kangaroo ticks. 3 host tick
Looks darker in colour
Contains eyes and ornate scutum (decorations on the scutum, red or yellow colour). Anal groove posterior to anus, mouthparts longer than BC. Oval shape BC
What are the general features of the Genus Rhipicephalus?
Mouthparts are the same length as the basis capituli
The basis capituli is hexagonal shape with angular margins
Eyes and festoons present
Coxa on the first pair of legs contain 2 long spurs. Anal groove is posterior to anus.
What are the two important species from Genus Rhipicephalus?
Rhipicephalus sanguineus –> brown dog tick. 3 tick host
Rhipicephalus australis –> cattle tick. 1 host tick
Importance of Rhipicephalus sanguineus
Is the brown dog tick
Can transmit babesia canis and Babesia gibsomi
Contains festoobs
Anal groove is posterior
Ventral shields present in males
Mouthparts are as long as the BC –> contains sharp edges (hexagonal shape)
Contain 2 long spurs on the coxa.
What are the important features of Rhipicephalus australis
Infects cattle
Transmits Babesia bovis and Babesia bigemina
used to be in a seperate genis caled Boophilus but has combined into Rhipicephalus
Mouthparts are as long as BC
Palps are shorter than hypostome - contains ridges
BC is hexagonal
Eyes present, no festoons
Coxa of first pair of legs have short spurs
Anal groove is small or absent
What are the important features of Genus Haemaphysalis?
Mouthparts are just as long as the basis capituli The second segment of the palps extend laterally BC is rectangular - flick to the sides Eyes are absent No ventral plates in males Contains festoons Anal groove is posterior 3 host tick
What is the important species of Haemaphysalis in Australia?
Haemaphysalis longicornis –> bush tick in NZ that infects cattle
Haemaphysalis bancrofti –?> wallaby tick that infects wallabys and kangaroos
How do hard ticks fixate onto the skin?
Dependent on the species and stage of the tick
Digits of the chelicereae will cut into the skin
Hypostome and chelicereae are introduced into the skin which anchor the tick.
A cement is produced by the salivary glands which flows into the wound and around the mouthparts –> hardens and strengthens the tick attachment to the host.
The cement causes local anesthesia and local immunosuppression to go undetected by the host.
