Ectoparasites

Question 1

What are 4 key features of ectoparasites?

Answer 1

Exoskeleton
Segmented
Jointed limbs
Ability to moult

Question 2

Compare insects and arachnids

Answer 2

Insects has 6 legs and distinct body regions (flies, fleas and lice)
Adults have 8 legs and fused body regions (ticks and mites)

Question 3

What are some Veterinary considerations surrounding ectoparasites?

Answer 3

1. ‘Fly worry’ - decline in milk, weight gain, livestock flies
2. Fly strike of sheep
3. Anaemia
4. Toxic and allergic responses (FAD, sweet itch)
5. Inflammation
6. Self-wounding/secondary infections
7. Pathogen transmission
8. Zoonoses

Question 4

What is an exoskeleton made of and what is its function?

Answer 4

• Cuticle of exoskeleton made of alpha-chitin
• provides support and protection
• muscles attached to inside of exoskeleton

Question 5

How do ectoparasites grow?

Answer 5

By moulting

Question 6

How does respiration occur in ectoparasites?

Answer 6

• Gas exchange via openings in the protective cuticle
• spiracles in insects
• stigmata in ticks/mites

Question 7

What are the 3 distinct body regions of an insect?

Answer 7

Head
Thorax
Abdomen

Question 8

Give the names of the different parts of the insects mouthpart

Answer 8

Palp
Mandible, maxilla - cutting
Labrum - upper lip
Hypopharynx - tongue
Labium, labellum- lower lip

Question 9

What are the body regions of acarines?

Answer 9

• Cephalothorax (head is fused with thorax)

- Abdomen

Question 10

How many pairs of legs are present in adult and larvae acarines?

Answer 10

Adult - 4

Larvae - 3

Question 11

Do either insects or acarines have wings or antennae?

Answer 11

Insects have 2 antennae and some species have wings

Acarines don’t have wings on antennae

Question 12

What part of the mouthpart is specific to ticks and what is its function?

Answer 12

Hypostome - anchors into the skin of host

Question 13

What is the only reason flies pester cattle?

Answer 13

Females must obtain protein to mature eggs

Question 14

How do mites and ticks reproduce?

Answer 14

Spermatophore (sperm packet) released into female through hypostome

Question 15

What are the terms given for complete and incomplete metamorphesis?

Answer 15

Holometabolous = complete - flies
Hemimetabolous = incomplete metamorphosis - lice and ticks

Question 16

What are control methods in dogs and cats?

Answer 16

• Stay kill
• Spot ons
• Chewable tablets
• Collars

Question 17

What is the mode of action of SPs?

Answer 17

• Repellency, knock down and rapid kill
• Excites cell membranes, depolarisation/Na ions,
• Hence paralysis

Question 18

What forms do SPs come in for use in controlling ectoparasites?

Answer 18

Pour-ons, Spot-ons, dips, sprays, ear tags against nuisance flies,
Lice and ticks. Collars for dogs. Absorbed onto skin and diffuses through coat
Not systemic

Question 19

What is the mode of action of MLs?

Answer 19

• Stimulate the release of GABA from parasitic nerve endings, enhancing the binding to its receptor on the post-synaptic motor neurone membrane
• Results in an increased flow of chloride ions causing hyperpolisation

Question 20

What forms do MLs come in for use in controlling ectoparasites?

Answer 20

Injectables, orally, pour-ons, spot-ons

Question 21

Which drug is used in companion animals in controlling fleas and ticks?

Answer 21

Fipronil

Question 22

Which drugs is used in companion animals, it is effective against fleas but doesn’t work against ticks?

Answer 22

Imidacloprid

Question 23

Name the latest products that are now available as readily absorbed, chewable tablets?

Answer 23

Isoxazolines:

• Fluralaner
• Afoxolaner
• Lotilaner

Question 24

What are the 2 main types of Insect Growth Regulators?

Answer 24

• Chitin inhibitors

- Juvenile hormone analogues

Question 25

Give some non-chemical uses for fly control?

Answer 25

• Barriers and protection
• Rugs
• Sticky tapes
• Pheromone and sugar baits