Sandflies

Question 1

What is the geographical range for sandflies?

Answer 1

As far north as France and as far south as Argentina. (50N, 40S)

Question 2

How many spp of sandfly are there and how many transmit human disease?

Answer 2

> 700

>50

Question 3

Describe the appearance of sandflies.

Answer 3

• Small (1/3 of a mosquito)
• Hairy (scales) (helps conserve water in arid conditions)
• Pointed wings (v shape above abdomen @ rest)
• Long spindly legs
• Parallel veins on wings (look striped)

Question 4

How long is the sandfly lifecycle?

Answer 4

Quite long- egg to adult in 4-5 weeks.

Question 5

How many eggs per oviposition?

Answer 5

10-120

Question 6

How many instars do the larvae have?

Answer 6

4

Question 7

What state is the pupa in?

Answer 7

Inactive state and has the skin of the 4th instar larvae.

Question 8

Describe the eggs of sandflies. Where are they oviposited?

Answer 8

Brown or black, very small, species-specific chorion.
Usually oviposited in damp locations with lots of organic material (such as cracks in walls, animal burrows, caves, termite mounds, tree buttresses).

Question 9

Describe the morphology of sandfly larvae.

Answer 9

0.5 cm
12 segments
Strong mandibles to chew organic detritus
Caudal bristles (on last segment)
Matchstick hairs (characteristic)

Question 10

What is the posited role of the matchstick hairs?

Answer 10

Locomotion and sensory function.

Question 11

Describe the morphology of the pupa of sandflies. Where are they located and in what position?

Answer 11

Inactive and can see the skin of the last larval stage. Red/ brown colouration. Cement onto substrates that are away from excessively moist areas. Get glued in an upright positioning

Question 12

What do adult sandflies feed on?

Answer 12

Both males and females take sugars (plant juices, fallen fruits, aphid booty lmao (aphid honeydew).

Question 13

Describe what happens to the sugar meal following feeding.

Answer 13

Sugar is diverted to a specialised organ called the crop. The very frist part of the sugar meal passes through the stomodeal valve and the rest is diverted to the crop. It is sterilised (unknown mechanism) and then it is passed to the midgut.

Question 14

Describe what happens to a blood meal.

Answer 14

Blood passes directly through the stomodeal valve into the midgut. The valve shuts when full to allow digestion.

Question 15

Describe how sandflies feed on blood.

Answer 15

Are pool feeders- use short serrated mouthparts to break capillaries to form a pool of blood on which they feed.
Only females feed on blood.

Question 16

Describe the host preferences of sandflies and how this plays a role in vectorial capacity/

Answer 16

host preference is dependent on the species of sandflies and therefore determines which species can be competent vectors e.g. if they do not ever feed on humans they cannot be vectors for human disease.

Question 17

When do female phlebotomine sandflies feed?

Answer 17

Night/ early evening and just before dawn.

Question 18

Describe how the structure of sandfly mouthparts are adapted for blood-feeding/ pool feeding.

Answer 18

Laciniae are behind the labarum and move back and forth to saw into the skin. Serrated mandibles push into the skin and saw independently.

Question 19

Where are leishmania parasites located inside sandflies?

Answer 19

In the gut- they never leave the gut! When parasites are found in the haemolymph, they are thought to be damaged parasites.

Question 20

Describe the mating of sanflies.

Answer 20

Do NOT swarm like mosquitoes and (most) other Diptera. They aggregate on surfaces that are attractive to females (for oviposition or feeding).

Males land first, secrete pheromones, flap wings to distribute these. Have a species-specific courting song and dance.

Sperm delivered in spermatophore via a sperm pump (like a hypodermic needle) to spermathecae

Question 21

How are sandfly pheromones useful in identification?

Answer 21

Species specific pheromones have been used to identify cryptic members within a species complex.

Question 22

How can male genital claspers be used to age a sandfly?

Answer 22

Male genital claspers undergo a 180 tip rotation within 24 hours of birth and so can allow ageing.

Question 23

What are cibarial teeth?

Answer 23

Teeth before female sandfly stomodeal valve.

Question 24

How do sandflies disperse? Describe their flying pattern. How does this affect the distribution of disease?

Answer 24

Don’t fly in strong wings but can disperse over 1.5km in light winds.
Flight becomes a characteristic hopping flight when they become close to a blood meal or the ground.

However, disease is focal as in dense vegetation, dispersal is less than 100m: sandflies tend to stay in the same area.

Question 25

Describe the resting habits of sandflies.

Answer 25

Rest in dark, humid sheltered sites. Can be exo or endophilic depending on the species.

Question 26

How do we collect sandflies?

Answer 26

This depends on the behaviour of the species of interest. - Directly search resting sites - Spray catches (spray insecticide and inspect sheet on the ground) - Human landing catches - Human bait - Traps (interceptive sticky traps, attractive traps)

Question 27

Why are attractive traps better than plain traps? What is the downside of traps?

Answer 27

Plain traps are likely to be stochastic. Traps rely on the LANDING of sandflies on the trap.

Question 28

Why are human landing catches/ human bait ethically questionable?

Answer 28

Because there is no effective prophylaxis for leishmania.

Question 29

Which sandflies are important in the old and new world respectively?

Answer 29

Phlebotomine in the old world and Lutzomyia in the new world.

Question 30

Why are sandfly bites painful?

Answer 30

Damage skin, immune reaction, saliva amplifies sensation of bite.

Question 31

What does a sensitised sandfly host mean?

Answer 31

Hosts previously exposed to the bite of a sandfly may have more severe irritations from the bite.

Question 32

What do sandflies spread?

Answer 32

Leishmania, bartonellosis.

Question 33

Where does Bartonella bacilliformis occur. Describe the course of infection. What is a characteristic feature of this disease? What is the outcome/ prognosis of the disease?

Answer 33

``` Andean foothills. Acute phase (fever, anaemia as they invade RBC), then chronic phase (>3 weeks, severe joint pain, immunosuppression). ``` Characteristic wart on the skin filled with the bacteria- allows the vector to bite this and pick up the next "dose". 50% mortality. Easily treatable with antibiotics if spotted.

Question 34

Which species causes sandfly fever? What type of pathogen is this caused by? Where does this occur? How many days following an infected meal can a female sandfly become infective? What are the symptoms?

Answer 34

- Phlebotamus papatasi - A virus - Africa, Middle East, India - 6-10 (and eggs can contain virus/ vertical transmission) - Fever, headaches and sometimes encephalitis.

Question 35

How many countries are endemic for Leishmania and how many cases are there?

Answer 35

88 countries | ~2 million

Question 36

Where is the majority of VL located?

Answer 36

``` India Sudan Bangladesh Nepal Brazil ```

Question 37

Where is the majority of CL located?

Answer 37

``` Afghanistan Iran Saudi Arabia Syria Peru Brazil ```

Question 38

Which is the species predominantly responsible for VL?

Answer 38

Donnovani

Question 39

Which is the species predominantly responsible for urban CL?

Answer 39

Tropica

Question 40

Which is the main vector for L donnovani?

Answer 40

Phlebotomus argentipes

Question 41

What are the main L species responsible for zoonotic leishmania?

Answer 41

L major and L aetheopica

Question 42

The fat sand rat acts as a reservoir for which species? And which sandfly infects it?

Answer 42

L major | P. papatasi

Question 43

How may epidemics of leishmania be caused?

Answer 43

Bringing in naive individuals into endemic areas (human migration or sandfly migration into naive populations).

Question 44

What is the pathology of leishmania in sylvatic cycles?

Answer 44

Usually asymptomatic. Except in dogs :(((

Question 45

How does sandfly control influence disease transmission?

Answer 45

A decrease in sandfly population strongly correlates with a decrease in disease incidence.

Question 46

Which factors affect the control of sandfly populations?

Answer 46

- Whether or not there are zoonotic reservoirs - Scattered or concentrated breeding sites? - If the non-domestic transmission is significant? (e.g. mainly indoors or mainly outdoors?) - If there is insecticide resistance - If endemic zones are widespread or scattered

Question 47

Which strategies may be effective to control anthroponotic leishmania?

Answer 47

- IRS and impregnated bednets | - Understanding where sandflies bite and rest

Question 48

Which strategies may be effective to control zoonotic leishmania?

Answer 48

- IRS/ITN may also be effective here (to control infection acquisition) - Insecticide-treated dog collars - Killing reservoir host/ destroying rodent breeding sites.

Question 49

How have sandflies adapted their behaviour based on human habits and how can understanding their behaviour inform us?

Answer 49

Sandflies accumulate outside during meal times and come in coinciding with our sleeping patterns. Can inform our behaviour- we can change our timing of eating and going to bed to avoid sandfly activity.

Question 50

What factor infuences the effectiveness of insecticide treated dog collars?

Answer 50

Whether or not non-domestic dogs/canids are important in transmission e.g. a larger non-domestic reservoir decreases the effectiveness of this technique.

Question 51

What are endectocides? What are the issues with this?

Answer 51

Orally administered insecticides which give their effects through the animal's follicles and skin. Concerns over milk quality in dairy animals etc.

Question 52

What is a possible reason that insecticide resistance is rarely seen/ is not a problem in sandflies?

Answer 52

Could be due to their slow growth rates which means that there is less time for reflection of benefits against the insecticides in the DNA.