Phylum Arthropoda, Class Arachnida, Order Prostigmata Flashcards
Where are the stigmata located?
Located at the level of the 4th pair of legs
What are the general features of Demodex spp?
Hosts - dogs, cats, cattle, goats, humans (different species)
Located in the hair follicles, sebaceous glands and the skin
All stages occur on the host
Is an elongated mite
Demodex canis = infects dogs hair follicles and sebaceous glands
The body is elongated, contains 4 short and stumpy pairs of legs which are located at the front of the body.
Opistosoma is striated (no leg region)
Gnathosoma is almost square
Eggs are spindle shaped, asymmetrical.
what is the lifecycle for Demodex canis?
Lives as a commensal in hair follicles, sebaceous glands and meibomiam glands of the skin
Females lay eggs in the hair follicle –> hexapod larvae –> 2 nymphal stages –> adults
Lifecycle is completed in 1 month
Develops into large populations and hair falls out.
What are some of the other species of Demodex?
Demodex bovis –> cattle, generates nodules, cysts which open up along the neck, shoulders and brisket
Demodex caprae –> nodules form on the face neck and shoulders, causes abcesses and crusting.
What are the general features of Cheyletiella species?
Called the walking dandruff
Hosts - cats, dogs, rabbits and humans
All three species are similar.
Gnathosoma is big, palps end with CLAWS
Legs end with comb like structures
Dorsal surface contain feather-like setae
idiosoma looks like a saddle. larger anteriorly and smaller posteriorly
What are the three species of Cheyletiella?
Cheyletiella yasguri - dogs
Cheyletiella blakei - cats
Cheyletiella parasitivorax - rabbits
What is the lifecycle of Cheyletiella species?
Spend their entire life on the host
Eggs are attached to the hairs of the host - 2-3mm above the skin.
Eggs unlike those of lice, do not have an operculum
Egg –> larvae –> 2 nymphal stages –> adults. 3-5 weeks to complete
The parasites do not burrow.
What are the general features of Trombicula autumnalis?
Only the larvae are parasitic
Hosts - mammals and birds
Only larvae will be located on the host, other stage will be in the enviro.
3 pairs of legs with feather like setae.
All pairs of legs end with 3 claws
Gnathosoma contains stout palps that end with 3 prongs
behind gnathosoma, contains a dorsal shield in rectangular shape.
On the dorsal surface, contain many feather- like setae.
Yellow/orangey colour
What is the Lifecycle of Trombicula autumnalis?
Female mites lay eggs in damp soils
Larvae hatch and as send on grass stems waiting for a host. Once on the host (ventral side of the body), the larvae feed on tissue fluids and digested tissues. Release into the soil –> nymphal stages –> adults.
What are the general features of Psorobia ovis?
Known as the sheep itch mite
Shape is almost circular
Legs are short and stout, attached equally distanced apart around the body
Located on the surface of the stratum corneum or the superficial layers of the stratum corneum within SHEEP.
