It’s summertime, and for many of us that means plenty of time outside – and, unfortunately, mosquitoes.
Author
- Daniel Eldridge
Senior Lecturer in Chemistry, Swinburne University of Technology
The combination of the is ideal for these blood-sucking insects to make their presence felt.
In the best-case scenario, they are a pest, delivering a highly unpleasant sting. At the other end of the spectrum, they are vectors for diseases responsible for .
To keep them at bay, many of us will reach for the bottle of insect repellent or citronella candles in order to avoid the bite and incessant itching that comes with it. But how do these repellents actually work?
A complex interplay
of research has gone into understanding how and why female mosquitoes – they are the ones that bite us – are attracted to people.
There is evidence showing they are attracted to the we exhale, lactic acid found in our sweat, and a variety of other and we give off. The interplay between all these factors is quite .
To ward off mosquitoes, physical barriers such as netting make for the best protection. However, while you might put netting around a backdoor patio and barbecue, doing this for any large space is simply not practical.
This is where repellents come in.
DEETerrent
There are a variety of mosquito repellents available.
The most tried-and-true products are based on a substance called N,N-diethyl-meta-toluamide, more commonly referred to as DEET.
This molecule has been commercially available since 1957, it was an effective insect repellent.
DEET is often used as a for investigating alternatives. , provided they are used according to direction, .
For example, it is recommended that when required, before the repellent. DEET products are not recommended for infants.
The exact mechanism by which DEET repels mosquitoes and other insects is .
Many studies link its success to mosquitoes having receptors that sense the presence of DEET, deterring them from closely approaching our skin. Some investigations suggest that when DEET is detected, it to us, while others show evidence that mosquitoes ” ” DEET.
There are also numerous reports demonstrating mosquitoes don’t bite when they DEET-treated skin. This is because DEET acts as a contact-based repellent and conveys a chemical message to mosquitoes to leave. that DEET likely works through a combination of the processes described here.
Effective alternatives
Another more recent family of mosquito repellent products rely on an active ingredient called picaridin (or icaridin).
The current consensus is that picaridin products are safe, and highly effective. For many, they are considered appealing as they as DEET.
Picaridin products have been reported to be as DEET, or in some cases, even , though the outcome depends on their concentration too.
The other repellent regularly reported as being effective is para-menthane-3,8-diol (PMD).
This is produced by chemical treatment of .
Untreated, this oil isn’t effective at repelling mosquitoes. However, have shown that PMD is an effective mosquito repellent.
The ability of these repellents to deter mosquitoes is .
In all cases, it’s important that an appropriate dose is applied, with re-application sometimes required to keep protection to a maximum. The performance of these products varies according to many other variables too, including .
What about citronella?
Citronella products, including candles and topical formulations, are popular choices for keeping mosquitoes away.
However, in systematic testing, these to be than DEET.
Studies have also shown that as you might like.
There are many other repellent products on the market.
Given the widespread interest in preventing mosquito bites, natural remedies abound. It’s important to recognise that natural and it .
In , DEET and picaridin are reported as having the greatest duration of protection (of the order of hours) and greatest effect on the mosquitoes. They are more thoroughly tested than many alternatives.
When others are tested, they are often found wanting.
One study described sound-based devices as being the repellent equivalent of . And although repellent bracelets contain working ingredients, they are largely ineffective in that form. This is because of insufficient concentrations of the active ingredient being “emitted”.
When it comes to preventing disease transmission via mosquitoes, the of the proven repellents far outweigh the risks.
