First one, then another. Bite! Slap! Bite! Before you know it, mosquitoes are descending from the skies to disrupt your backyard summer soiree. How can such a tiny, fragile insect cause so much pain, suffering and annoyance?
Notwithstanding the death and disease that mosquito-borne pathogens cause around the world, the annoyance caused by mosquito bites can be seriously disruptive (and yes, they might bite you more than your friends). The reactions to bites can be severe, and when swarms of mosquitoes swell in the suburbs, the impacts can be substantial.
It may be impossible to stop mosquitoes flying in from local bushland or wetland areas. The mosquitoes breeding in your neighbours' yard won't have much trouble flying over the fence either, and while local authorities may instigate control programs and new technologies are deployed to reduce, replace or wipe out local mosquito populations, there is still plenty you can do to beat the bite of mosquitoes yourself.
Here's how you can build a mosquito-free zone around your friends and family.
Slip, slop and spread it around
Just as you'd slip on a shirt, slop on sunscreen and slap on a hat toprotect from sunburn, two of these three apply to mosquito bite protection too.
Slipping on long-sleeved shirts and long pants will protect from mosquito bites. Darker colours tend to attract mosquitoes and even though pale clothing won't repel mozzies, perhaps you won't attract as many. Also, go for something loose-fitting so the mozzies cannot bite through to your skin, and perhaps rethink the skin-tight active wear for your next bushwalk or fishing trip.
Slopping on some insect repellent is the best way to go. Pick a product that contains either diethyltoluamide (commonly known as DEET), picaridin, or "oil of lemon eucalyptus". These products will all provide long-lasting protection, as long as they're applied correctly.
This is where the "spread" comes in.
A dab of repellent here and there won't work. A squirt on the back of your shirt or a puff above your head won't do the trick either.
Regardless of formulation, be it cream, lotion, gel, roll-on, pump-spray or aerosol, there needs to be complete coverage of all exposed skin. If you miss a bit, the mosquito will find that chink in your armour and bite it.
You can sweat it off, rub it off or wash it off while swimming, so keep in mind that you'll need to reapply your chosen repellent throughout the day.
Some people are reluctant to use these "chemical" repellents, and feel anxious about perceived health risks. However, these products are used billions of times every year with very few reports of skin irritation or other adverse outcomes. You're at far greater risk (from mosquito-borne disease) by not using these products.
Even if you go looking for alternative products, such as those that contain plant-based ingredients, keep in mind these will need to be reapplied more frequently to provide the same level of protection. Some "home-made" repellents containing essential oils can irritate the skin, so stick with products that are registered with the Australian Pesticides and Veterinary Medicines Authority (APVMA).
Is there an alternative to creams and sprays?
You may not like the sticky feel on your skin but topical repellents are really the best way to stop mosquito bites. There are, however, a few options available that can at least reduce the number of bites and are worth a try.
However, you should skip the wrist bands and patches - they don't work.
Mosquito coils are a mainstay of outdoor life in many mosquito-plagued parts of the world. Studies have shown that they are good at reducing the number of bites, but not so good at preventing disease. To get the best protection, go for those that contain an insecticide, not just plant-based products, as they will kill any mozzies buzzing about. Smelly smoke will just make life uncomfortable for the mozzies.
If the idea of a smoke-filled backyard isn't for you, you can try some of the new "smoke-free" devices.
Instead of a smouldering coil, there are some battery-operated and "plug-in" devices that release products that kill or repel mosquitoes. These devices typically release an insecticide from a heated pad or oil reservoir.
These can be useful when used indoors at night to stop the pesky buzzing, but there are also devices that can be taken on the go. Whether you're clipping them to your belt or backpack or sitting them on your picnic table, they won't provide an impenetrable shield against mosquitoes but they will at least keep some away.
A smartphone isn't a smart option
Browse your favourite app store and you'll find a stack of apps claiming to keep mosquitoes at bay. Most claim to emit an ultra-sonic sound that mozzies don't like. But the reality is that a mosquito on the search for blood isn't put off by anything!
Long before smartphones hit our pockets, "sonic repellents" were marketed as an alternative to topical repellents and mosquito coils. There has never been any evidence that these devices work.
Mosquitoes do respond to sound - but generally only the males who are on thelookout for love. And males don't bite anyway.
Take the fight to the backyard!
Perhaps the best option of all to keep the bites out of your backyard is to stop mozzies breeding there in the first place.
Any water-holding container, from a rainwater tank to a wading pool, or even an upturned bottle top, can be home to mosquito wrigglers. You could apply insecticides to these habitats but the better option is to tip them out, cover them up or, in the case of rainwater tanks, ensure they are screened to prevent mozzies getting in and out. Cleaning up your backyard is a pretty good idea too.
Mosquitoes do love a shaded backyard, and unfortunately there are no plants you can add to garden beds that keep mosquitoes away. While the concentrated extract of some plants may work as an insect repellent, the trees and shrubs themselves do not.
There is still a lot to be done to ensure the public is adequately informed when it comes to mosquitoes and the health threats they pose. If we can get a bit more slip, slop and spreading happening this summer, perhaps a few more Aussies will avoid getting sick from mozzie bites.
Modified mosquitoes could help fight against malaria
For the first time, malarial mosquitoes have been modified to be infertile and pass on the trait rapidly - raising the possibility of reducing the spread of disease.
The mosquito species Anopheles gambiae is a major carrier of dangerous malaria parasites in sub-Saharan Africa, where 90 per cent of annual malaria deaths occur. Malaria infects more than 200 million people each year and causes more than 430,000 deaths.
Now, a team of researchers led by Imperial College London have genetically modified Anopheles gambiae so that they carry a modified gene disrupting egg production in female mosquitoes. They used a technology called 'gene drive' to ensure the gene is passed down at an accelerated rate to offspring, spreading the gene through a population over time.
Within a few years, the spread could drastically reduce or eliminate local populations of the malaria-carrying mosquito species. Their findings represent an important step forward in the ability to develop novel methods of vector control.
Normally, each gene variant has a 50 per cent chance of being passed down from parents to their offspring. In the Imperial team's experiments with Anopheles gambiae, the gene for infertility was transmitted to more than 90 per cent of both male and female mosquitoes' offspring.
The technique uses recessive genes, so that many mosquitoes will inherit only one copy of the gene. Two copies are needed to cause infertility, meaning that mosquitoes with only one copy are carriers, and can spread the gene through a population.
This is the first time the technique has been demonstrated in Anopheles gambiae. The team targeted three different fertility genes and tested each for their suitability for affecting a mosquito population through gene drive, demonstrating the strength and flexibility of the technique to be applied to a range of genes. The results are published today in the journal Nature Biotechnology.
"The field has been trying to tackle malaria for more than 100 years. If successful, this technology has the potential to substantially reduce the transmission of malaria," said co-author Professor Andrea Crisanti from the Department of Life Sciences at Imperial.
"As with any new technology, there are many more steps we will go through to test and ensure the safety of the approach we are pursuing. It will be at least 10 more years before gene drive malaria mosquitoes could be a working intervention," added Professor Austin Burt from Imperial's Department of Life Sciences.
Many current measures to control malaria rely on reducing populations of malarial mosquitoes, such as insecticides and bed nets. These have proven very successful in reducing the spread of malaria, however these approaches face important costs and distribution challenges, as well as growing issues of resistance.
A control measure relying on genetic spread through a targeted population of malaria mosquitoes could complement these interventions without adding dramatically to the health budget of resource-constrained countries.
"There are roughly 3,400 different species of mosquitoes worldwide, and while Anopheles gambiae is an important carrier of malaria, it is only one of around 800 species of mosquito in Africa, so suppressing it in certain areas should not significantly impact the local ecosystem," said lead author Dr Tony Nolan from the Department of Life Sciences at Imperial.
To test the gene drive, the team first identified three genes that impacted female fertility by disrupting the activity of suspected target genes. They then modified the genes with the CRISPR/Cas9 endonuclease, a type of DNA cutting tool that can be designed to target very specific parts of the genetic code.
When chromosomes carrying these modified genes come into contact with chromosomes without the gene variant, an enzyme is produced that cuts it, causing a break. The broken chromosome uses the chromosome carrying the desired variant as a template to repair itself, copying in the code with the altered gene variant.
The team aims to improve the expression of their gene drive elements, but also to find more genes to target, which would reduce the possibility of mosquitoes evolving resistance to the modification.
Exploring target genes is also helping the researchers to learn more about basic mosquito biology. "We hope others will use our technique to understand how mosquitoes work, giving us more ammunition in the fight against malaria," said first author Andrew Hammond, also from Imperial's Department of Life Sciences.
Infertility gene in mosquitoes to curb malaria
They used a technology called "gene drive" to ensure the gene for infertility is passed down at an accelerated rate to offspring -- spreading the gene through a population over time and raising the possibility of reducing the spread of disease.
Within a few years, the spread could drastically reduce or eliminate local populations of the malaria-carrying mosquito species. The mosquito species Anopheles gambiae is a major carrier of malaria parasites in sub-Saharan Africa, where 90 percent of annual malaria deaths occur.
Malaria infects over 200 million people each year and causes more than 430,000 deaths."Scientists have been trying to tackle malaria for more than 100 years. If successful, this technology has the potential to substantially reduce the transmission of malaria," said study co-author professor Andrea Crisanti.
Normally, each gene variant has 50 percent chance of being passed down from parents to their offspring.In the team's experiments with Anopheles gambiae, the gene for infertility was transmitted to more than 90 percent of both male and female mosquitoes' offspring.
The technique uses recessive genes so that many mosquitoes will inherit only one copy of the gene.Two copies are needed to cause infertility, meaning that mosquitoes with only one copy are carriers, and can spread the gene through a population.This is the first time the technique has been demonstrated in Anopheles gambiae.
The results were published in the journal Nature Biotechnology.