Australia is home to some of the world’s most deadly creatures. So it’s not surprising that local scientists turned to venom from spiders and sea anemones to combat the insect responsible for the most deaths in the world – mosquitoes.
Scientists from Macquarie University have genetically engineered male insects so they carry toxins that are transferred during mating, shortening the lifespan of females. Their research, published in the journal Nature Communications, found the process could reduce their lifespan by 37 to 64 per cent. It also concluded blood feeding rates could plummet by 40 to 60 per cent compared to established methods.
Lead author Sam Beach told Yahoo News biocontrols are preferable to insecticides as mosquitoes are becoming resistant to them, and chemicals don’t just kill their target species, they also cause indiscriminate harm to the wider environment.
“We’re still in the early stages of development of this technology and there are a lot of regulatory and safety concerns that need to be grappled with. But five to 10 years is a realistic time frame for field trials to get started,” he said.
Related: Seven dire reasons it might be time to leave Australia – from floods to fungus
Source: Macquarie University
Why were previous mosquito biocontrols flawed?
Previous attempts at biocontrols involved releasing sterilised males into the environment so females couldn’t successfully breed, but this had one major drawback.
“Male mosquitoes don’t blood feed, it’s only the females who bite so they can start producing their eggs. She wasn’t producing any offspring but the downside was she was still hanging around and spreading disease,” Beach said.
“So we’d only see a reduction in numbers in subsequent generations. So if a city was in the midst of some epidemic, it wasn’t any comfort that the situation would get better in three to six months.”
Rather than use harmful chemicals as a control measure (background) the scientists opted for venom from the Mediterranean snakelocks sea anemone (bottom) and banana spider (top). Source: Getty
The new biocontrol is the first of its kind and could offer a fast alternative to insecticides. The trials used venom from Brazil’s banana spider (Phoneutria nigriventer) and the Mediterranean snakelocks sea anemone (Anemonia sulcata) on common fruit flies (Drosophila melanogaster).
Are mosquitoes a major threat in Australia?
For years mosquitoes were nothing more than a nuisance on mainland Australia, making it hard to sleep at night because of their irritating buzz, and causing itchy bites. But they’re now responsible for a growing number of dangerous diseases including Buruli ulcer, Ross River virus and Japanese encephalitis. And as the climate changes, mosquitoes that carry dengue fever, chikungunya and Zika virus could become established.
But overseas these diseases are already causing major impacts on health and economic growth. It’s estimated around 1 million people die from health complications associated with mosquitoes every year and between 400 and 700 million contract some sort of illness from their bites.
Less than 10 per cent of the world’s 3,500 mosquito species carry diseases that impact human health. So the team would only target those which are a threat.
Could the venom harm frogs and fish that eat mosquitoes?
Their research indicates there is little danger that animals that eat mosquitoes will be significantly affected by the venom. That’s important because 40 per cent of amphibians and 25 per cent of freshwater fish are threatened with extinction and they are common predators.
“When we were looking at what proteins, we wanted to make sure they were very specific for insects,” Beach said.
“These proteins also evolved to be very toxic when directly injected. And they’re much less toxic when eaten by an animal. So we will still obviously do quite a comprehensive safety profiling of this, but we are fairly confident.. it shouldn’t have any adverse effects on any predators.”
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