‘A big step forward’: fungus enhanced with spider toxin proves deadly for mosquitoes

Scientists have genetically modified a fungus so that it can kill mosquitoes as part of a new drive to fight malaria.

The trial in Burkina Faso – which was conducted in a sealed model village – killed more than 99 per cent of 1,500 mosquitoes and is being hailed as a “big step” forward by the study's authors.

However, critics are concerned that the genetically modified fungus could impact other insects and even animals.

“Fighting malaria through genetic engineering is dangerous” Nnimmo Bassey of the Health of Mother Earth Foundation, an advocacy group based in Nigeria, told NPR.

“I'm heavily worried that Africans are the preferred guinea pigs for experimentation, and Africa is going to become a large laboratory for risky experimentation.”

The experiment was conducted by scientists from the University of Maryland (UMD) in the US and the IRSS research institute in Burkina Faso and its findings published this week in  the journal Science.

They took a naturally occurring fungus, Metarhizium pingshaense, and combined it with the DNA of a venomous  Australian Blue Mountains funnel-web spider. While the fungus does kill mosquitoes in its unaltered state, when combined with the new spider genes it becomes far more deadly and fast-acting.

Experts say the fungus could “destroy” mosquito populations.

“It’s a really exciting study and it looks like this has great potential to become another tool in the interventions toolbox,”  Dr David Weetman, senior lecturer at the Liverpool School of Tropical Medicine, told The Telegraph.

“It’s a big step forward in that they have studied the fungus in a realistic environment and shown that it can effectively destroy a mosquito population, by killing them but also depressing the ability of female mosquito to reproduce.”

Roughly 435,000 people die from malaria each year and the battle against the disease is stalling. According to the World Health Organization, the number of cases reported worldwide rose by three million in 2017, to a total of 219 million.

Part of the problem is that mosquitoes are becoming resistant to the most common insecticides, prompting a race among scientists to find alternatives.

The fightback is taking a number of routes. New bednets impregnated with multiple insecticides, or even antimalarials drugs, are being developed to kill the mosquitoes already immune and prevent the further spread of resistance. And last month the first malaria vaccine was launched in a pilot in Malawi after 30 years of development.

But genetic engineering is also being explored, of which this modified fungus is just one example.

Researchers have developed GM mosquitoes that could kill off its entire species by spreading a faulty gene. If it works in the wild, the controversial technology – called gene drive – could help eliminate malaria.

However the scientists behind the modified transgenic fungus say that their aim is not to wipe out all mosquitoes, but to combat insecticide resistance.

The fungus would be used inside houses, much like an insecticide, and has not been designed to spread naturally.

In the trial in the “mosquito sphere” in Burkina Faso – an enclosed model village complete with huts and plants – the scientists used an oil emulsion to attach the fungus spores to a black cotton sheet, which they hung in a chamber.

Of the 1,500 adult mosquitoes released into the space, just 13 were still alive 45 days later.

“Simply applying the transgenic fungus to a sheet that we hung on a wall in our study area caused the mosquito populations to crash within 45 days,” Dr Lovett said. “And it is as effective at killing insecticide-resistant mosquitoes as non-resistant ones.”

The scientists also said that the fungus only infects and attacks mosquitoes, so should not be a threat to other insect populations – though critics remain concerned that the deadly fungus could inadvertently kill other organisms and damage the balance of fragile ecosystems.

“These fungi are very selective,” said Raymond St. Leger, a professor of entomology at UMD and co-author of the study. “They know where they are from chemical signals and the shapes of features on an insect's body. The strain we are working with likes mosquitoes.

“It won't go to that trouble for other insects, so it's quite safe for beneficial species such as honeybees,” he added.

The report added that as the fungus spores are large, sticky and sensitive to ultra-violet light, they would not naturally become airborne and spread.

But Dr Wheetman said that the team also needed to confirm the safety of the modified fungus for livestock and humans in future trials.

“It does seem that this is only effective in mosquito populations,” he said. “But it is warranted to suggest the safety of modified fungus needs to be confirmed for people and livestock.”

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