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[♪ Intro] Unsurprisingly, mosquitoes aren’t exactly
a fan favorite insect.
Not only do many species use us as their personal blood
buffet, but they are also infamous for spreading deadly diseases, from
yellow fever to malaria.
As you can imagine, there’s been a lot of attention put towards controlling
these mosquito-spread diseases, typically through managing the insect’s
populations.
Unfortunately, we’re not taking out just the mosquitoes with these
measures.
The insecticides we use can also be bad for the environment
and human health.
On top of that, we’re seeing insecticide resistance crop up in some
mosquito species.
But there may be a new way that makes both humans and mosquitoes
happy that involves little more than a spoonful of sugar.
You might feel like all mosquitoes are out to get you, but on an individual
level, they actually rarely go for blood.
Male mosquitoes never do, relying solely on nectar and other sugary
sources for their meals.
And females only need a blood meal as an added nutritional bump right
before developing eggs.
It’s just that there are so many mosquitoes around, that even the rare blood meal is still
too many for our liking.
A 2019 study published in PLOS Biology discovered something very
interesting about female mosquitoes with bellies full of sugar.
We already knew that mosquitoes have certain genes called
vitellogenins that are involved in egg production.
When vitellogenin proteins are released into the mosquito’s
circulatory system, this triggers cells in the ovary to begin forming egg yolks.
But this research determined that one particular vitellogenin gene, called
Vg-2, also plays a big role in driving a mosquito’s blood seeking behavior.
It turns out, up until the mosquito gets a blood meal, this gene is actually
repressed, meaning it’s switched off and not doing a whole lot.
It’s not until after they’ve jabbed their proboscis into somebody for their
favorite drink that changes in their hormones trigger the Vg-2 gene to
create its egg-inducing proteins.
So not only is vitellogenin vital for egg production, but mosquito feeding
behaviors appear to directly depend on whether these genes are
switched on or off.
This research also found that the expected wave of vitellogenin seen after
a blood meal was also observed after days of sugar feeding.
And most importantly, females with access to a sugary liquid were much
less interested in human hosts than those who were only given access to
water.
The higher the concentration of sugar, the lower their desire for blood.
But this seemed to happen more consistently in young females, meaning
those who had only been adults for a week or less.
As the females got older, they began to feel the lust for human
blood again, even with access to sugar.
So beware, those 17 day old mosquitoes might still be out to get you.
The researchers don’t know if this preference was because the
mosquitoes just weren’t really feeding much on the sugar by that point, or
if they were using the sugar to fuel their search for a blood meal.
In the future, we might be able to trick these blood suckers into eating
more sugar so they don’t even want our blood.
And better yet, we may be able to find a way to control vitellogenin
in order to quiet down the urge to drink blood in the first place, without all
the sugary bribery.
But while it’s too early to know what that might look like, new mosquito
control strategies may emerge thanks to this research using new methods
that don’t focus on killing them, but simply reduce their biting urges.
And who knows, maybe soon enough we’ll be putting away the citronella
candles and replacing them with tiny mosquito-sized versions of
hummingbird feeders.
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