Insect Ectoparasites

Question 1

Ectoparasites can play triple role of:

Answer 1

1. Parasite
2. Intermediate Host
3. Vector

Question 2

ARTHROPODA phylum consists of:

Answer 2

1. Insects: Flies, lice, fleas

2. Arachnida: mites, ticks

Question 3

Vector

Answer 3

Animal (often arthropod) that transmits an infective organism from one host to another

Question 4

Mechanical vector

Answer 4

Transmits organisms directly to recipient host without development or multiplication of organism occurring.

• Not essential for life cycle of infective organism

Question 5

Biological vector

Answer 5

Intermediate (final) host
- infective organisms undergo development or multiply or both before being transmitted to recipient host.

• Essential for LC of infective organism

Question 6

Diptera

Answer 6

True flies

Question 7

Life cycle of Buffalo fly

Haematobia irritans exigua

Answer 7

2-3 weeks (like most flies)

1. Females lay egg on fresh dung
2. eggs hatch in <24 hrs
3. Larvae (maggots) in dung for 4-5 days
4. Puparia in dung or soil 5-7 days
5. Young adult fly
6. Fly stays on host to feed

Question 8

Screwworm fly (Cocliomyia hominivorax)

Answer 8

1. Female flye lays 4 batches of 400 eggs on edge of wound
2. After 12h, larvae hatches and enters wound for feeding
3. After 5 days, larvae drops to ground and develops into pupae for 8 days
4. After 2 days, fly is sexually mature

• highly aggressive

Question 9

Fly strike on sheep is mostly cause by

Answer 9

Lucilia cuprina

Question 10

Signs of external fly infestation

Answer 10

1. Fly “worry”
   - Restlessness, tail swish, kicking
   - swollen ears, bloody legs
2. Fly infection and strike:
   - biting at wool or infested area
   - rubbing, itching
   - anaemia from blood loss
   - loss of condition/ death
   - away from other sheep

Question 11

Control methods for fly infestation

Answer 11

1. Physical barriers
2. Fly traps
3. Insecticides
4. Mulesing

Question 12

Mosquitoes are vectors for:

Answer 12

1. Protozoa e.g. Malaria
2. Viruses e.g. Dengue virus
3. Worms e.g. Heartworm

Question 13

Phthiraptera Order

Answer 13

Lice

Question 14

Lice

Answer 14

Spends entire life cycle on host

• have claws & 6 legs
• all stages are parasite
• host specific & region specific

Question 15

Sub-order: Mallophaga

Answer 15

Biting and chewing lice (rounded front, chomps scurf)

• feed by chewing hairs, skin –> ITCHY

Question 16

Sub-order: Anoplura

Answer 16

Sucking lice (sharp front end for piercing skin)
--> TRAUMA/ANAEMIA

Question 17

Transmission of lice occurs through:

Answer 17

Direct contact but can also occur via fomites

Question 18

Epidemiology of Lice

Answer 18

• obligate parasite
• Peak infestations in winter
• Infestations heavier in sheep with poor conditions and already affected by disease (lower immunity)
• spread by direct contact, but can survive for short periods on combs, fences
• host specific

Question 19

3 Control of Lice

Answer 19

1. Killed by light (shearing) or water
2. Chemical control: pour-ons after shearing
3. Dipping shears between animals

Question 20

Lice diagnosis

Answer 20

1. Sheep rubbing against fences, fleece tags
2. Fleece partins to look for lice
3. Biting lice present on woolly areas
4. sucking lice on hairy skin
5. Use lice detection test

Question 21

Are sucking lice more or less active than biting lice?

Answer 21

Sucking lice are less active than biting lice

Question 22

Why is winter the peak production for lice?

Answer 22

In summer, skin temps and humidity is unsuitable for lice reproduction

Question 23

Flea features

Answer 23

1. Exoskeleton
2. 6 legs
3. Head, abdomen, thorax
4. Genal & pronatal combs
5. Lateral compression
6. no wings
7. Body has scales and hairs

Question 24

Why are fleas so hard to catch?

Answer 24

They can jump high due to protein resilin in their leg hinge (97% elasticity)

Question 25

Flea cycle

Answer 25

3 weeks cycle | -egg to larvae to pupa to adult flea

Question 26

Flea bites

Answer 26

are painful. When hypersensitivity developes--> itchy | Skin trauma occurs and skin thickens

Question 27

Diagnosis of fleas

Answer 27

lesions including flea and flea dirt

Question 28

Flea epidemiology

Answer 28

- development increases with warmth and humidity - eggs fall to ground and larvae and pupae survive in carpet and soil - pupae respond to vibrate so hatch only when host is near - most are in animal's environment

Question 29

Control of fleas

Answer 29

Vacuum, wash blankets, treat and remove all flea reservoirs (other pets)

Question 30

Treat fleas

Answer 30

Using flea treatment that kills fleas rapidly after feeding and before and can develop will deplete the environment of larvae and pupae