Importance of mosquito longevity Flashcards
Around how many mosquitos live long enough for parasites to develop?
Less than 1/4 even in long-lived species.
How often do mosquitos feed?
Every 3 days
What percentage of mosquitos would be infectious at day 13?
20%
Describe how ovaries look in newly born/nulliparious mosq?
Trachioles are tightly bundled.
Describe how ovaries look in parious mosq?
Trachioles are looser as have been stretched by carrying eggs.
What structure on the ovary can indicate how parous a female has been
Dilatations- 1= monoparous etc.
How was a constant survival curve/probability of being alive from one day to the next shown to be linear?
Counting dilatations and survival (dilatations indicating age).
How was mark release recapture used to relate gonotrophic age to calendar age?
Used to show they were closely related i.e. calendar age basically the same as gonotrophic age.
At the end of the dry season, when abundance in mosquitos decreases, why does transmission increase?
Because the old females are what is left - relative importance of longevity over abundance.
Why do survivorship curves not always look like the predicted standard?
Because of many factors causing eggs in breeding sites not always being consistently laid.
Also because the time spent as different instars of larvae is not always equal or the same.
How can you measure age?
- Cuticular hydrocarbon ratio (lots of noise)
- Near-infrared spectroscopy (trained with samples of known age)
Why may gonotrophic age be more important than calendar age?
Because of the variability of development and growth time with temperature–>slowsdown in the cold
Also because mortality rates vary more per cycle than per day.
Why may mortality vary more per cycle than per day?
Because they engage in risky behaviour around once per cycle e.g.biting incurs the risk of swatting.
Describe the paddy paradox
Rice villages have around the same rates of malaria as non rice villages despite having more larval breeding sites.
Because:
-More money
-More roads
-Better housing
-Buy bednets!
More mosquitos but people better defended.
Describe the relationship between vectorial capacity and density. Why is this?
Vectorial capacity increases with density but reaches a ceiling and even goes down at high density.
Overcrowding at the larval stage causes increased competition and smaller, weaker females to be born, decreasing their vectorial capacity. This also causes them to live less long.
