Let’s
re-learn our insect repellent technique!
We would
think that as dwellers of this tropical metropolitan state called Singapore, we
would have figured out everything we need to know about preventing insect
bites, wouldn’t we?
But have we
been doing it correctly? Do you still get bitten by mosquitoes even though you
are pretty sure you do not forget about repellents before you step out? Did you
get insect bites at certain spots on your body where you least expected?
Let’s
wonder no more and let’s revisit the basics of insect repellents.
The science of repellent – simplified
To be
honest, there have been debates on how biting insects respond to the repellents
on our skin. We will explain to you two versions, as proven by research.
1. The Invisibility Cloak
If Harry
Potter were to go backpacking on our beautiful tropical paradise of South East
Asia, he would wish he packed his invisibility cloak in.
Researchers
from Rockefeller University, New York have studied how insects respond to DEET
and found that repellents like DEET confuse the receptors in the insect nervous system that
process odours. This response masks the odours of our body that would normally
attract biting insects.
In other words, they can’t sense us.
Illustration
by Chris Gash
2. Too Stinky for Mozzies
You would
think that biting insects like mosquitoes have no issue with bad smell,
wouldn’t you?
Think
again. Another group of researchers from University of California Davis,
California studied the same thing and found the opposite. Mosquitoes do dislike the smell of DEET. According to the research,
mosquitoes have olfactory receptor neurons that can detect repellents like DEET
display avoidance behaviour by flying away from the source of smell.
We can say
that even mosquitoes have their own least favourite smell.
Illustration
by Chris Gash
The basics of repellent application - explained
We have
seen so many types of dance moves people make when they apply insect
repellents. From the hip hop-style rapid repetition up and down your arms and
legs as you rub the repellent, to the new-age swirl of aerosol repellent from
head to toe. There’s no need to be kiasi
and let’s learn these basics:
1. Cover up
your skin – As much as you reasonably can in Singaporean weather with long
clothing.
2. Apply on
exposed skin only – Leave no empty spot, and be mindful of your facial area and
wounds.
3. Apply over clothing – Add a layer of repellent on your clothing next where possible.
Definitely
do not do this to your face. Apply on your hand first, rub and then gently
apply to your face and ears with your hands. Photo credit: Daniel Grill
Your arsenal of insect repellents - debunked
There is a
myriad of insect repellents in the market from drugstore all the way to online
shops. What are the differences and how do we know any one of them is good?
Insect
repellents sold in Singapore have be registered with National Environment
Agency (NEA), but exemption applies to those of plant/natural origins such as essential
oil,neem and citronella.
So how do
we choose good repellents from the second category since it is not regulated by
NEA?
According
to Centers for Disease Control and Prevention (CDC), it is recommended to use
repellents approved by Environment Protection
Agency (EPA)that
contain any of the active ingredients below, as these are proven safe and
effective, even for pregnant and breastfeeding women:
·
DEET
·
Picaridin
(known as KBR 3023 and icaridin outside USA)
·
IR3535
·
Oil
of lemon eucalyptus (OLE) or para-menthane-diol (PMD)
·
2-undecanone
© Jo-Lynn
Teh, BCE
Jo-Lynn Teh is ESA Board Certified Entomologist based in Singapore. While her specialisation is on tropical insects that affect public health and agriculture, Jo-Lynn’s passion is also to help people understand insects. Find her on LinkedIn.
