Blood type, metabolism, exercise, shirt color and
even drinking beer can make individuals
especially delicious to mosquitoes.
An estimated 20 percent of people, it turns out, are especially delicious for mosquitoes, and get bit more often on a consistent
basis. And while scientists don’t yet have a cure for
the ailment, other than preventing bites with insect
repellent (which, we’ve recently discovered, some mosquitoes can become immune to over time), they do have a number of ideas regarding why
some of us are more prone to bites than others.
Here are some of the factors that could play a role: Blood Type Not surprisingly—since, after all, mosquitoes bite
us to harvest proteins from our blood—research
shows that they find certain blood types more
appetizing than others. One study found that in a controlled setting, mosquitoes landed on people
with Type O blood nearly twice as often as those
with Type A. People with Type B blood fell
somewhere in the middle of this itchy spectrum.
Additionally, based on other genes, about 85
percent of people secrete a chemical signal through their skin that indicates which blood type
they have, while 15 percent do not, and
mosquitoes are also more attracted to secretors
than nonsecretors regardless of which type they
are. Carbon Dioxide One of the key ways mosquitoes locate their
targets is by smelling the carbon dioxide emitted
in their breath—they use an organ called
a maxillary palp to do this, and can detect carbon dioxide from as far as 164 feet away. As a result,
people who simply exhale more of the gas over
time—generally, larger people—have been
shown to attract more mosquitoes than others.
This is one of the reasons why children get bit less
often than adults, on the whole.
Exercise and Metabolism In addition to carbon dioxide, mosquitoes find
victims at closer range by smelling the lactic acid,
uric acid, ammonia and other substances expelled
via their sweat, and are also attracted to people
with higher body temperatures. Because
strenuous exercise increases the buildup of lactic acid and heat in your body, it likely makes you
stand out to the insects. Meanwhile, genetic factors
influence the amount of uric acid and other
substances naturally emitted by each person,
making some people more easily found by
mosquitos than others. Skin Bacteria Other research has suggested that the particular
types and volume of bacteria that naturally live on
human skin affect our attractiveness to
mosquitoes. In a 2011 study, scientists found that having large amounts of a few types of bacteria
made skin more appealing to mosquitoes.
Surprisingly, though, having lots of bacteria but
spread among a greater diversity of different
species of bacteria seemed to make skin less
attractive. This also might be why mosquitoes are especially prone to biting our ankles and feet—
they naturally have more robust bacteria colonies. Beer Just a single 12-ounce bottle of beer can make
you more attractive to the insects, one study found. But even though researchers had suspected this was because drinking increases the
amount of ethanol excreted in sweat, or because it
increases body temperature, neither of these
factors were found to correlate with mosquito
landings, making their affinity for drinkers
something of a mystery. Pregnancy In several different studies, pregnant women have been found to attract roughly twice as many
mosquito bites as others, likely a result of the fact
the unfortunate confluence of two factors: They
exhale about 21 percent more carbon dioxide and are on average about 1.26 degrees
Fahrenheit warmer than others. Clothing Color This one might seem absurd, but mosquitoes use
vision (along with scent) to locate humans, so
wearing colors that stand out (black, dark blue or
red) may make you easier to find, at least
according to James Day, a medical entomologist at
the University of Florida, in commentary he gave to NBC. Genetics As a whole, underlying genetic factors are estimated to account for 85 percent of the variability between people in their attractiveness
to mosquitoes—regardless of whether it’s
expressed through blood type, metabolism, or
other factors. Unfortunately, we don’t (yet) have a
way of modifying these genes, but… Natural Repellants Some researchers have started looking at the
reasons why a minority of people seem to rarely
attract mosquitoes in the hopes of creating the
next generation of insect repellants.
Using chromatography to isolate the particular chemicals these people emit, scientists at the UK’s Rothamsted Research lab have found that these natural repellers tend to excrete a handful of
substances that mosquitoes don’t seem to find appealing. Eventually, incorporating these
molecules into advanced bug spray could make it
possible for even a Type O, exercising, pregnant
woman in a black shirt to ward off mosquitoes for
good. http://blogs.smithsonianmag.com/science/2013/07/why-do-mosquitoes-bite-some-people-more-than-others/

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