Every once in a while, when the temperature stays in triple digits well into September or October, I remember the autumns of my childhood in Chicago—sweaters and jackets and kicking a pile of dead leaves. And I miss the seasonal changes that the desert lacks.
So when the water heater needs replacing or the drip irrigation lines aren't working, again, I crank up the computer and explore condos and townhouses in cities where there is a winter. And states where there is no drought.
But then I remember. Snow doesn't bother me, but mosquitos do. We may have tarantulas and scorpions, but the desert is not kind to mosquitos. More than a minor irritant, they carry and transmit diseases like malaria, the West Nile virus and now, chikungunya (pronounced chick-en-gun-yuh) a particularly unpleasant mosquito born virus that turned up in Florida last summer.
Last week, houseguests who had been visiting the Midwest, reminded me of how often it seems that one person gets most, if not all, of the attention of the flying pests. Turns out that scientists are still trying to figure out why.
Please join me below the fold for some of what they have discovered and how you can use this information when planning your summer barbecue.
There is a new study that supports the theory that a large part of the attraction that an individual holds for a mosquito is genetic. James Logan of the London School of Hygiene & Tropical Medicine led the study which was published in Plos One in April.
Somehow, the researchers managed to talk 18 pairs of identical twins and 19 pairs of fraternal twins to stick their arms in y-shaped tubes to determine which ones the mosquitos found most attractive.
“Identical twins are genetically identical and non-identical twins show genetic differences. If attractiveness [to mosquitoes] is down to our genes, we would expect to see a high correlation between the identical twin pairs and a lower correlation between the non-identical twin pairs. And this is exactly what we found,” says Dr. Logan.
They still don't know whether there is something in the genes that attracts the mosquitos or that repels them. Either way, continuing the research could lead to new forms of mosquito repellents. And with 534,000 deaths from malaria worldwide in 2013, including 430,000 children under age five, new repellents are needed.
“Once we find out which genes might be involved,” says Dr. Logan, “it may allow us to identify new repellents, and detect individuals who are most at risk of being bitten, and therefore disease. Then possibly develop a drug, like a pill, which would up-regulate the production of natural repellents by the skin, revolutionising the way we protect ourselves against mosquito bites.”
Another study, published in March of 2015 in the mBio, the open access journal of the American Society for Microbiology, looked at the ability of malaria infected blood to draw mosquitos to the host. According to an
NPR report on the study:
But here's the kicker: The parasite makes these odors in a way similar to the way flowers make their sweet fragrance. "You can basically think of a malaria parasite as a plant in the dark," says molecular microbiologist Audrey Odom, who led the study.
The malaria parasite has a special compartment in its single cell that's similar to chloroplasts in plants. But malaria's compartment doesn't photosynthesize light to make sugars. Instead it manufactures building blocks for the parasite's cell.
Some of these building blocks, Odom and her team found, are aromatic. They smell sweet to a mosquito, just like a flower does.
Not all mosquitos carry the malaria parasite but those that do are attracted to people who already have the illness which makes spreading it more efficient.
Mosquitos find carbon dioxide very attractive. It acts as a homing beacon for the female mosquito who needs the protein from your blood to develop her eggs. People who are breathing heavily, perhaps after working out or running, are likely to be perceived as a lighthouse by mosquitos. Since holding your breath is only a temporary fix, it might be wise to go indoors until your breathing returns to normal.
According to Dr. Jonathan Day, a medical entomologist and mosquito expert at the University of Florida, as quoted by Time Magazine's Markham Heid,
"Pregnant women and overweight or obese people tend to have higher resting metabolic rates, which may make them more attractive to mosquitoes," he explains. Also, drinking alcohol or physically exerting yourself raises your metabolic rate—and also your appeal to winged biters, he adds. (Exercising before grabbing a beer and heading outside = asking for trouble.)
Dr. Day also explained that mosquitos are not strong flyers, so if you must be outside, try pointing a fan in your direction. That same lack of flying ability is why they stick close to the ground. (It is not just to nibble on your ankles. They do that because your blood is closer to the surface there.) While they are close to the ground, they look for prey that differentiates itself from the background, like dark clothing on a clear day. Lighter colors tend to blend in much better and are harder for the creatures to find.
Beware of too much activity at dawn and dusk because, just like a cat, mosquitos see objects in motion much more readily than they see objects at rest.
Finally, according to the website Mosquito World (yes, there is such a site),
They also prefer the scent of cholesterol, folic acid, bacteria from drying sweat and many perfumes, colognes and shampoos.
The secret to remaining relatively mosquito-bite free at your summer barbecue may be in your guest list. Make sure to include the individual who complained last year of being eaten alive by mosquitos. If it is genetic, he/she will likely continue to be attractive to the flying pests. Sit some distance away from her/him, and make sure they have access to beer and wine. Also, try to sit near the fan, wear light clothing and get someone else to do the carrying and serving which will make them far more visible to mosquitos.
And if that fails, you can always fall back on DEET-containing repellents. Should you prefer alternate methods, Shape has a list of seven ways to avoid the bites, including eating lots of garlic, planting lemongrass and lavender, and hanging plastic bags half filled with water and a few pennies.
Or you can move to the desert where it is too hot outside during the summer for barbecues or mosquitos.