Vectors

Question 1

General mosquito life cycle

Answer 1

1. Eggs laid in water
2. Larvae - feeds and moults (lasts 10 days - 12 months!)
3. Pupae - undergoes metamorphosis
4. Adult mosquito

Question 2

How to differentiate male and female mosquitoes

Answer 2

Males have plumose antennae (long hairs)

Question 3

What is a vector species complex

Answer 3

A species complex is a group of closely related species that are morphologically similar or indistinguishable by microscopy. They are important because they may have different host preferences, resting behaviour (indoor/outdoor) feeding behaviours and
breeding habitat requirements.

Question 4

Why is insecticide based control difficult in house flies?

Answer 4

1. Huge range of potential habitats makes covering all these logistically difficult.
2. feeding sites may be very distant from breeding sites.
3. Multiple emergences of insecticide resistance mechanisms, to different classes of insecticides.
4. High reproductive rate and fast life cyclemeans that rebound of population is very fast.

Question 5

What facilitated the movement of Aedes Egypti out of Africa?

Answer 5

Human movement
- slave trade
- trading vessels
- suez canal

Question 6

What is the role of climate change in vector born diseases

Answer 6

• affect vector population distribution and density
• increases life span / survival - increases probability that parasite can complete life cycle/ mosquito can bite twice.
• increase in reservoir hosts
• social and environmental drivers (housing, density, human behaviours)

Question 7

Vector control of Aedes

Answer 7

Source reduction - very difficult as larval sites are millions of induvidual containers. Need community engagement - local removal of containers, cover and treat (larviciding) domestic water sources.

Fogging - used during outbreaks. No residual effects - repeat treatments required once new eggs hatch.

Insecticide residual spraying - has more long-lasting effect in homes

Insect growth regulator - pyriproxyfen - a synthetic version of mosquito hormone - prevent development of larvae into pupae. Safe to humans. May be spread around on the bodies of mosquitos themselves

Genetically modified male release - sterile males or dominant lethal gene (very expensive)

Gene drive - spread of genes that stop virus transmission

Use of Wolbachia - used to drive refractory genes into populations

Question 8

What does hemimetabolous mean?

Answer 8

No pupal stage - direct from larvae to adult

Question 9

Sandfly species and location

Answer 9

Phlebotomous - Old world
Lutzomiya- New world