Lecture 7 - Insects: Diptera - Calliphoridae

Question 1

Match the below flies to their species name.

Sarcophaga sp

Chrysomya spp

Calliphora stygia

Lucilia sericata

Calliphora augur
Lucilia cuprina
Chrysomya varipes

Answer 1

A = Lucilia cuprina

B = Lucilia sericata

C = Calliphora stygia

D = Calliphora augur

E = Sarcophaga spp

F = Chrysomya varipes

G = Chrysomya spp

Question 2

Give the species names for these flies. Which one is more widely distributed worldwide?

Answer 2

Top = Lucilia cuprina

Bottom = Lucilia sericata (more worldwide distribution)

Question 3

Describe the lifecycle of Lucilia cuprina in the disease cutaneous myiasis. Give the approx day lengths of each stage.

Answer 3

Day 0: larvae hatch on sheep hours after being laid

Days 1-2: First instar consumes protein from sheep’s exudate, moults into second instar

Days 1-2: Second instar burrows into skin and starts feeding on sheep’s flesh
Days 2-19: Second instar moults into third instar, which matures

Days 2 - 19: Mature third instar drops to ground at night
3 - 7 days later: third instar has pupated
OVER WINTERS IN SOIL and HATCHES IN SPRING

Shortest possible time for life cycle is 17d in summer

Question 4

What are the three most important contributing host factors to BREECH strike?

Answer 4

Wrinkle score

Soiling due to not being sheared or crutched

Soiling due to diarrhoea (e.g GI parasitism)56

Question 5

What are four contributing host factors to BODY strike?

Answer 5

Fleece rot / dermatitis (due to excessive wetting of wool and skin)

Sway back

Wrinkle score

Wax level of fleece

Question 6

What additional factor post-fleece rot contributes to Lucilia cuprina targeting the host?

Answer 6

Proliferation of Pseudomonas spp. on the epidermis adds to olfactory cue

Question 7

List five avenues for reducing sheep susceptibility to Lucilia cuprina strike.

Answer 7

Crutching

Tail docking

Mulesing

Breed away from wrinkles

Remove any ‘conformational faults’

Question 8

List six possible avenues for reducing the number of flies able to strike sheep. Include any major problems with these.

Answer 8

Treat cases of strike early in season - hard bc. some covert strikes
Burn or deeply bury carrion to reduce habitat for secondary strikers
Fly traps
Genetic manipulation either sterile male method or knock out pathogenic genes (still in progress)
Vaccines (expensive, still in progress)
Chemical management (OPs - resistance, GRs)