Nanogirl Michelle Dickinson: Birth control one way to hit mosquito numbers

With birth control, scientists hope to reduce the mosquito population enough to break the cycle of deadly disease transmission. Photos / Getty Images; File

COMMENT: Mosquitoes making you itch during the summer BBQ season? Thanks to new scientific research, the future is starting to look bite-free – scientists have created a birth control method, just for mosquitoes, designed to help eradicate them without affecting the rest of the environment.

After humans, mosquitoes are the most dangerous animal on the planet. Across the world over 500 million people are affected each year by serious consequences from mosquito bites - malaria, yellow fever, chikungunya, Zika and dengue, for example can all result from just one bite and can be fatal.

Luckily, in New Zealand mosquitoes are just a nuisance with their bites causing nothing more than an itch - the result of a reaction that our bodies have to the mosquito's saliva that it injects while biting.

To date, getting rid of mosquitoes has involved insecticides and pesticides, which are known to have a negative effect on the ecosystem. Some mosquitoes are becoming resistant to these insecticides due to our long term reliance on chemical treatments, forcing scientists to come up with alternatives.

Researchers from the University of Arizona decided to look at how the mosquito was different from other insects. Using bioinformatics, they searched for and identified genes that were unique to mosquitoes.

The function of many of these genes were unknown, so using a technique known as RNA Interference they turned off each of these genes individually, using small RNA molecules to try to see what the effect of the change was on the mosquito.

Of the 40 mosquito-specific genes they tested and turned off, one seemed to be responsible for the structure of the eggs that the female mosquitoes laid.

When the scientists blocked this protein, which they called Eggshell Organising Factor or EOF-1, the female mosquitoes laid eggs with defective shells, causing the normally dark eggshells to be pale and porous.

This defect caused many of the eggs to collapse, and the embryos inside the egg to die. The effect was long-term and once the gene treatment had been given to the mosquito all of its eggs were defective for the rest of her 50 day life. Although the female mosquito would continue to bite she was not able to reproduce, thus reducing the overall number of mosquitoes in an area over only a few months.

The research published in the journal PLOS Biology showed that the treatment - because it was mosquito specific - could potentially be applied to large areas known to harbour infected mosquitoes without affecting other organisms nearby.

Although the complete eradication of the mosquito species sounds tempting, as nectar eaters they are still great pollinators for plants and provide a food source to birds and fish. The end goal would be to reduce the mosquito population significantly enough to break the cycle of disease transmission between mosquitoes and humans in high risk areas rather than get rid of them completely.

In the meantime, while we wait for this new birth control to be commercialised, the best way to get rid of mosquitoes in your back garden is to check for and remove any standing water.

Mosquitoes breed in standing water, so removing small puddles that may have accumulated in flower pots or other garden containers gives them fewer places to breed meaning fewer mosquitoes in your garden at least.

Another easy trick, if it's not windy, is to add some standing fans to your outdoor area. Mosquitoes may be good biters, but they aren't great fliers - and struggle to fly in fast moving air, so by blowing a breeze over your outdoor gathering area you not only keep people cool but also bite free as well.