Dry Conditions Lead to More Mosquito Bites (But Not More Mosquitos)

Dry Conditions Lead to More Mosquito Bites (But Not More Mosquitos) on

Find out why – and when – they want your blood

If you’ve left your home lately, you’ve probably encountered a mosquito or two. We are in one of the rainiest times of the year, and when you add water to the heat, the little buggers love to come out to play.

If you’re constantly having to use anti-itch lotion, you are probably longing for the drier, colder days ahead. But, sadly, while this may reduce the number of mosquitos, it may not cut down on the biting.

What researchers discovered

Female mosquitos require blood in order to nourish their eggs, but they also drink it when they’re thirsty. And an accident in a lab at the University of Cincinnati earlier this year related to this has led to what could end up being an important discovery.

When students were studying dehydrated mosquitos, some escaped from their vial. Immediately, they became aggressive and were trying to bite. As a result, researchers began a study that took a closer look at dehydrated common house mosquitos.

The theory was that a dehydrated mosquito would have a suppressed metabolism and not want to eat as much blood. But it turned out to be just the opposite; about 30 percent of the dehydrated mosquitos went looking for blood immediately.

“Normally only 5 or 10 percent of female mosquitoes will feed at any time, depending on the species,” said UC biology professor Joshua Benoit. “Dehydration has a big impact on whether they feed normally or not.”

Researchers then released adult mosquitos in a big, mesh-enclosed space at a UC research center that mimics natural conditions. After about a week, they brought in a disk of blood covered in a membrane resembling an animal host. Blood-feeding mosquitos were then collected twice – once after it rained and then again after a dry period. Researchers discovered that the mosquitos suffering from dehydration were more likely to look for a blood meal compared to the ones with ample fluids on hand.

“It makes sense,” said study co-author Elise Didion. “We find the highest transmission rates of West Nile virus during droughts because mosquitos may use blood meals to replace the water they lose.”

What this means for the future

Because mosquitos are so dangerous due to the diseases they spread, studies like this one could help save lives. UC mathematical sciences professor Yanyu Xiao collaborated with the research team in order to create models that could predict biting rates and disease transmission.

“In my literature review, I found that typical disease infection wasn’t over the summertime but in transitory times when water levels shrink and the flowers dry up,” Xiao said. “Look at the daily pattern of rainfall and seasonal drought.”

The scary part is that it doesn’t take very long at all for mosquitos to become dehydrated. “We saw the behavioral effects within two or three hours under low humidities and higher temperatures,” she added. “It was completely changing their behavior.”

Knowing this information and getting keener insight into mosquito behaviors can be invaluable, says study co-author Christopher Holmes.

“You could see effects on mosquitos that probably will be exacerbated with the increasing frequency of drought, increasing duration, and increasing severity,” Holmes said. “If we know how mosquitos react to drought, we can better predict when you’ll see a disease outbreak. It’s a step in the right direction toward understanding how the environment affects mosquitos, which we really can’t answer right now.”

South Florida just can’t seem to win

So, we have to deal with many mosquitos in the wet weather and then thirstier mosquitos in the dry weather, which pretty much covers the whole calendar. Fortunately, a mosquito misting system can help keep your home protected all year long. Get in touch with Platinum Mosquito Protection for a free onsite consultation.

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