Blackflies, midges and sandflies Flashcards

1
Q

Latin for blackflies

A

Simulidae

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2
Q

Describe the identifying features of blackflies

A

Small, black, humpbacked biting flies
1,4 - 6mm long
Large, compound eyes
Brush-like mouth part acting as a filter

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3
Q

What is the taxonomy of simulidae based on

A

Polytene chromosomes (lack of molecular data)

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4
Q

What are blackflies also called?

A

Buffalo gnat

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5
Q

Describe the life cycle of black flies

A
  1. Eggs
    - 150-600 eggs dropped from air/vegetation/substrates into fast flowing water
    - hatch after 2-30 days (survive 2-8 months dependent on species and water temperature)
  2. Larvae
    - growth temperature dependent (cold = slower, diapause)
    - develop in flowing water
    - 4-9 larval stages usually 7
    - takes 1-6 months
    - larvae anchor themselves by spinning small, silken pad with mouth parts and inserting row of hooks from abdomen into the silk pad
  3. Pupae
    - housed with air bubble which bursts when adult emerges
    - delicate silk cocoon in some species
    - 4-7 days
  4. Adult
    - males and females feed on nectar and mate
    - males die
    - females feed on blood and develop an egg mass
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6
Q

What does severity of infection from black flies depend on?

A

Number of bites

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7
Q

Which disease do blackflies transmit?

A

Onchocerciasis

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8
Q

Which organism causes onchocerciasis and what is it?

A

Onchocerca volvulus
Filarial nematode

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9
Q

What is onchocerciasis also called and what does it cause?

A

African river blindness
Acute + longstanding infection

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10
Q

What other condition can onchocerciasis cause and what are its features?

A

Blackfly fever (North America)
Relatively mild
- headache
- nausea
- fever
- swollen neck lymph nodes

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11
Q

Describe the life cycle of onchocerca volvulus

A

Blackfly stages:
1. Blackfly takes blood meal (L3 larvae enter bite wound)

Human stages :
2. Subcutaneous tissues
3. Adults in subcutaneous nodule
4. Adults produce unsheathed microfilariae that are typically found in skin and lymphatics of connective tissue but also occasionally peripheral blood, urine, sputum

Blackfly stages:
5. Blackfly takes blood meal and ingests microfilariae
6. Microfilariae penetrate blackfly’s midgut and migrate to thoracic muscles
7. L1 larvae
8. L3 larvae
9. Migrate to head and blackfly’s proboscis

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12
Q

How long does the blackfly stage last?

A

1 week

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13
Q

Discuss blackfly control

A

Difficult
Usually aimed at larval stages
Involves aerial insecticides
Target breeding sites (BTI ingestion via water)
Best defense = repellants (DEET, permithrin treated clothing)
Ivermectin treatment to kill larvae
Doxycycline to kill adult worms

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14
Q

What is the latin for biting midges?

A

Coulicoides

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15
Q

How do you identify biting midges?

A

Tiny 1-3mm
Yellow-brown (red when filled with blood)
Spotted wings
Stout-legged flies
Mouth parts consist of fleshy sheath containing 4 cutting blades which cause skin lacerations

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16
Q

What is the latin for the biting midges family?

A

Ceratopogonidae

17
Q

Discuss the life cycle of biting midges

A

2-8 weeks total
1. Eggs
- laid in damp breeding sites
- require water to develop
- require blood to mature
- number depends on species and blood meal size
2. Pupae 2-3 days
3. Adults undergo complete metomorphosis

18
Q

What does holometabolous mean?

A

Eggs -> larvae -> pupae -> adults

19
Q

Which organism do biting midges transmit?

A

Mansonella perstans (filarial worm)

20
Q

What are the clinical features of mansonella perstans infection?

A

Dermatitis
Skin lesions

21
Q

Why are biting midges important for vets?

A

Blue tongue (sheep, cattle)
African horse sickness

22
Q

Discuss the life cycle of mansonella perstans

A

Midge stages:
1. Midge takes blood meal (L3 larvae enter bite wound)

Human stages:
2. Adults in peritoneal/pleural cavity (sometimes pericardium)
3. Adults produce unsheathed microfilariae that reach bloodstream

Midge stages:
4. Midge takes blood meal (ingests microfilariae)
5. Microfilariae penetrate midge’s midgut and migrate to thoracic muscles
6. L1 larvae
7. L3 larvae
8. Migrate to head and midge’s proboscis

23
Q

Difference between male and female midges?

A

Females larger

24
Q

What are the 3 types of mansonella?

A

Perstans
Streptocerca
Ozzardi

25
Q

Discuss biting midge control

A

Removal trapping using CO2 attractant to insecticide
Repellants (DEET)
Window screens

26
Q

What is the latin for sandflies?

A

Phlebotomus

27
Q

Discuss the identification of sandflies

A

small
Large black eyes that are continuous with 5th and 6th antennae
Long, slender leggs
Piercing mouthparts for taking blood in FEMALES only
Clear, unmarked, hairy wings

28
Q

Discuss sandfly flight

A

Weak fliers
Tend to move via weak hopping flight

29
Q

Discuss sandfly lifecycle

A
  1. Eggs
    - hatch after 4-20 days (longer if cold)
  2. Larvae
    - undergo 4 instars
  3. Pupae
    - 6-13 days
  4. Adult sandflies
30
Q

What is special about sandfly anatomy?

A
  1. Pedicle of male’s antennae contains Johnston’s organ for hearing
  2. Non-segmented abdomen extends past head
31
Q

What disease do sandflies transmit?

A

Leishmaniasis and arboviruses

32
Q

Discuss the life cycle of leishmaniasis

A

Mammal stage:
1. Metacyclic promastigotes transferred during feeding
2. Actively invade macrophages, granulocytes or are phagocytosed
3. Promastigotes transform into amastigotes and multiply by simple division
3. Amastigotes leave infected cells

Female sandly stage”
4. Amastigotes transferred during feeding
5. Release in the midgut
6. Transform into procyclic promastigotes
7. Simple division into metacyclic promastigotes
8. Promastigotes migrate to pharyngeal valve and transferred during feeding

33
Q

Discuss control of sandflies

A

Residual insecticides (organophosphates, carbamates, pyrethroids)
Breeding/resting site elimination (fill cracks, destroy termite mounds)
Reservoir animal control (dispose of decomposing animal flesh)

34
Q

What is the difference between midges and sandflies?

A

Midges
- small, 2 winged fly
- forms swarms
- breeds in moist environments
- belong to several families of non-mosquito
- Nematoceran Diptera
- do not bite
- mansonella perstans

Sandfly
- small, hairy fly
- tropical and subtropical
- Psychodidae subfamily of Phlebotomina
- blood-sucking
- leishmaniasis and poppataci fever

35
Q

What is Poppataci fever caused by?

A

Phlebovirus

36
Q
A