Deadly beetroot juice cocktail kills mosquitos in six hours, research shows

An insecticide cocktail of beetroot juice laced with a synthetic toxin is an effective mosquito repellent and could be an additional tool in the fight against diseases such as malaria and dengue, researchers have found. 

The solution – christened “pink juice” by the researchers – mimics blood so closely that the insects prefer this meal, the study, published in Communications Biology, shows. 

Researchers say that the eco-friendly, low cost solution should be tested in the field and has the potential to be used widely.

“This mixture, that we call pink juice, is a harmless, inert, eco-friendly solution, but it is naturally toxic for female mosquitos when ingested by them,” said Noushin Emami, associate professor in the department of molecular biosciences at Stockholm University.

“Altogether, we here provide a proof-of-concept for a specialised and eco-friendly feeding trap that can be deployed where needed. We hope to see it tested in a field setting and in combination with other vector control approaches,” she said. 

The key ingredient in the cocktail was HMBPP – a molecule produced by the malaria parasite – alongside a toxin, called fipronil sulfone. 

Researchers tested other toxins - capsaicin, savory oil and boric acid - but found that the mosquitoes did not feed on solutions containing these. 

The addition of HMBPP was crucial in attracting the mosquitoes – adding just a toxin to the juice did not attract the insects, the researchers found. Mosquitoes found HMBPP so tasty that they would even feed on it if it was added to coffee. 

The insecticide cocktail killed all the mosquitoes that fed on it within one to six hours, the research showed. 

The paper highlighted how additional tools are desperately needed in the fight against malaria, which kills around 450,000 people every year. Mosquitoes are highly adaptable and have developed resistance to the insecticide used to treat bed nets. 

There is also emerging evidence that some mosquitoes have switched their behaviour to biting during the day, rather than at night, rendering bed nets ineffective. 

The cocktail could also be used against mosquitoes that carry other diseases such as dengue.

Last week the World Health Organization gave the go ahead for the first ever malaria vaccine to be rolled out in sub Saharan Africa but said that preventive measures were still desperately needed. 

“There are a number of new, exciting, high tech approaches targeting mosquitoes which are entering large-scale testing but I believe that there is a lot of potential in developing very simple, but highly effective solutions based on simple molecules and using materials which are not only affordable but also accessible to almost anyone. We used beetroot in this study to demonstrate exactly this point,” added Dr Emami.

She said that the "cocktail" was harmless to humans because only very small amounts of toxins were used.

"Our goal is not to use traditional pesticides at all in the final products but substances which are natural and completely harmless to animals, but harmful to mosquitoes when digested."

Dr Emami added that "beauty of this solution is that it can be combined with different delivery techniques: from feeder station/passive traps to deploying it as spay/dew on foliage so mosquitoes can drink it from the droplets."

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