Why do mosquitoes bite me more? Here are two reasons why

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Summer is here and so are those pesky, bloodsucking mosquitoes.

Their presence is an inevitable fact of the season. But do you ever wonder why some people — perhaps yourself — are "mosquito magnets" while others can seemingly keep the insects at bay?

Two new studies shed light on possible reasons why. And the answer, according to scientists, may lie in your soap and how heavily you breathe.

Some soaps can increase a person's attractiveness for mosquitoes, while others can reduce it, one group of researchers found, adding that soaps "significantly alter the olfactory signature (or scent) of human hosts."

One study published May 10 in the scientific journal iScience tested four popular soaps — from brands Dove, Dial, Simple Truth and Native — and found so-called "natural" products, like Simple Truth and Native soaps, generally contained fewer plant-derived chemicals that are detectable by mosquitoes compared to average soaps, like those from Dove and Dial.

As well, while the chemicals present in "natural" products such as Native tended to repel the insects, the compounds in average soaps increased attractiveness.

The average soaps "had a certain class of chemicals that were actually related to mosquito attractiveness and had certain plant compounds," said Manisha Kulkarni, an associate professor of epidemiology and public health and the University of Ottawa. Kulkarni was not involved with the study.

Kulkarni and the study's researchers, however, noted that it's difficult to predict to what degree certain products will alter an individual's attractiveness to mosquitoes, since a person's natural odour also plays a significant role.

"The results really varied with each individual study participant (because) there's this interaction between the soap used and the individual themself," said Kulkarni. "So, the individual's own chemical compounds were interacting with those present in soap to either enhance or reduce attractiveness."

Another study published in Current Biology in May suggests carbon dioxide is also associated with human attractiveness for mosquitoes. Researchers found carbon dioxide paired with body heat and other human odours play a critical role in host attraction for the African mosquito Anopheles gambiae, known for spreading malaria.

"Carbon dioxide depends on your level of activity as well as your breathing rate and also body size," noted Kulkarni, who was also not involved with this study. "Small children, for example, produce less than larger adults."

This study could have major implications for potential disease control in sub-Saharan Africa, where malaria is prevalent, added Kulkarni.

"The major malaria control tools now are long-lasting insecticidal nets that people sleep under that are treated with different types of insecticides," she said. "But we’ve seen a lot of increasing insecticide resistance over recent years, which is really concerning, given the reliance on these tools for malaria control.

"So if we’re able to develop new repellents, based on this type of chemical technology that can reduce human attractiveness, then we have another tool in our tool box."

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