US mosquito numbers have crashed during a historic drought

Rep ese tative
Image
of
d y
e vi o me tal
co ditio s
affecti g
mosquito
umbe s
a d
public
health
(AI-ge e ated
image)

Mosquitoes
have
all
but
va ished
f om
pa ts
of
the
U ited
States
this
summe ,
a d
eside ts
i
states
like
Mi esota
say
they
ca ot
emembe
a
seaso
this
quiet.
A
histo ic
d ought
sweepi g
th ough
the
West
a d
Midwest
has
cut
mosquito
populatio s
by
as
much
as
50
to
70
pe
ce t
i
some
egio s.
No mally
that
would
sou d
like
good
ews
fo
a yo e
ti ed
of
bug
bites.
But
scie tists
a e
wo ied,
because
the
d op
i
mosquito
umbe s
has
coi cided
with
a
sha p
ise
i
West
Nile
vi us
cases
ac oss
the
cou t y.
The
two
t e ds
appea
to
co t adict
each
othe ,
yet
esea che s
say
the e
is
a
clea
a d
t oubli g
expla atio
behi d
why
fewe
mosquitoes
ca
still
mea
mo e
disease.

Why
mosquito
populatio s
have
c ashed
ac oss
the
US

The
d ought
d ivi g
this
yea ‘s
mosquito
decli e
has
bee
u usually
seve e,
st etchi g
f om
the
weste
states
th ough
the
Midwest
a d
touchi g
places
like
Mi esota,
No th
Dakota
a d
Colo ado.
I
Colo ado,
some
expe ts
estimate
mosquito
umbe s
have
falle
by
as
much
as
70
pe
ce t
compa ed
to
a
typical
yea .
Reside ts
have
oticed
the
diffe e ce
fi stha d,
with
seve al
telli g
local
epo te s
they
have
ba ely
eeded
i sect
epelle t
this
summe
despite
yea s
of
deali g
with
heavy
mosquito
activity.
The
cause
is
simple.
Mosquitoes
eed
sta di g
wate
to
b eed,
a d
a
d y
sp i g
followed
by
a
pu ishi g
summe
has
left
fa
fewe
puddles,
po ds
a d
wetla ds
fo
them
to
lay
eggs
i .

How
d ought
is
quietly
aisi g
the
isk
of
West
Nile
vi us

Eve
with
fewe
mosquitoes
buzzi g
a ou d,
health
officials
say
the
da ge
f om
West
Nile
vi us
has
ot
eased
at
all.
So
fa
this
yea ,
the
vi us
has
caused
a
wave
of
i fectio s
seve e
e ough
that
case
umbe s
a e
u i g
well
ahead
of
the
histo ical
ave age,
with
the
cu e t
seaso
t acki g
as
o e
of
the
wo st
i
mo e
tha
two
decades.
The
Ce t es
fo
Disease
Co t ol
a d
P eve tio
has
bee
mo ito i g
the
su ge
closely,
a d
its
o goi g
su veilla ce
data
shows
i fectio s
sp eadi g
ac oss
doze s
of
states
eve
as
ove all
mosquito
cou ts
fall.
A izo a
has
eco ded
the
highest
co ce t atio
of
cases
a d
deaths
this
yea ,
with
Colo ado
a d
Utah
also
seei g
elevated
umbe s.

What
the
scie ce
says
about
d ought
a d
disease
sp ead

The
expla atio
lies
i
how
d ought
cha ges
mosquito
a d
bi d
behaviou
athe
tha
how
ma y
mosquitoes
exist.
Whe
wate
sou ces
sh i k,
both
mosquitoes
a d
the
bi ds
that
ca y
West
Nile
vi us
a e
fo ced
to
gathe
a ou d
the
same
limited
puddles,
po ds
a d
i igatio
ditches.
That
c owdi g
i c eases
the
cha ces
of
a
mosquito
biti g
a
i fected
bi d
a d
the
passi g
the
vi us
o
to
a
pe so .
A
pee – eviewed
study
published
i
the
jou al
P oceedi gs
of
the
Royal
Society
B
titled

The
pa adoxical
impact
of
d ought
o
West
Nile
vi us
isk:
i sights
f om
lo g-te m
ecological
data
fou d
that
d ought
co ditio s
pa adoxically
aise
the
ate
of
West
Nile
vi us
i fectio
eve
as
they
educe
ove all
mosquito
umbe s,
a
patte
the
esea che s
li ked
to
mosquitoes
a d
bi ds
co ce t ati g
a ou d
dwi dli g
wate
supplies.
The
fi di g
echoes
what
public
health
expe ts
have
obse ved
o
the
g ou d
this
yea ,
whe e
a
quiete
mosquito
seaso
has
ot
t a slated
i to
a
safe
o e.

Why
the
mosquito
seaso
itself
is
getti g
lo ge

Beyo d
this
yea ‘s
d ought,
esea che s
poi t
to
a
b oade
climate
t e d
that
is
eshapi g
mosquito
activity
ac oss
the
cou t y.
A
a alysis
by
the
o p ofit
esea ch
g oup
Climate
Ce t al
fou d
that
the
tempe atu e
co ditio s
suitable
fo
mosquitoes
to
sp ead
West
Nile
vi us
ow
last
about
18
days
lo ge
each
yea
o
ave age
compa ed
with
the
ea ly
1970s,
based
o
data
f om
hu d eds
of
Ame ica
cities.
Nea ly
all
of
the
cities
studied
showed
a
i c ease
i
these
so-called
mosquito
disease
days,
with
the
biggest
jumps
eco ded
i
the
southeast,
o theast
a d
o thwest.
That
lo ge
wi dow
gives
mosquito
populatio s
mo e
oppo tu ities
to
ebou d
o ce
d ought
co ditio s
ease,
a d
expe ts
cautio
that
a
quiet
summe
ca
be
followed
by
a
much
la ge
swa m
if
ai
etu s
sudde ly.

What
this
mea s
goi g
fo wa d

Public
health
specialists
say
the
cu e t
lull
i
mosquito
umbe s
should
ot
lead
to
a
false
se se
of
secu ity.
Species
behave
diffe e tly
u de
st ess,
a d
some,
i cludi g
those
that
th ive
a ou d
sh i ki g
lakes
a d
ese voi s,
a e
ma agi g
to
multiply
eve
as
ove all
populatio s
fall
elsewhe e.
That
has
al eady
played
out
a ou d
Utah’s
G eat
Salt
Lake,
whe e
mosquitoes
emai
abu da t
despite
d y
co ditio s
elsewhe e
i
the
state.
Expe ts
co ti ue
to
ecomme d
the
same
p ecautio s
du i g
a y
d ought
yea ,
i cludi g
clea i g
sta di g
wate
a ou d
homes,
usi g
app oved
epelle ts
a d
stayi g
ale t
to
symptoms
of
West
Nile
vi us,
si ce
eve
a
smalle
mosquito
populatio
ca
ca y
a
outsized
isk.
With
mosquito
populatio s
expected
to
ebou d
o ce
the
d ought
b eaks,
esea che s
say
this
yea ‘s
pa adox
is
a
emi de
that
fewe
bites
do
ot
always
mea
less
da ge .

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