Diet pill may prove answer to mosquitoes

Mosquito ovaries and pond scum are the unappetising ingredients of a "diet pill" for bugs that could reduce human illness and…

Mosquito ovaries and pond scum are the unappetising ingredients of a "diet pill" for bugs that could reduce human illness and death caused by insect-borne diseases.

A researcher at the University of Florida developed the concoction that when eaten by hungry mosquito larvae makes it impossible for them to feed, lay eggs or survive.

"We hope this can stop the advance of malaria and other mosquito-borne diseases," said Dr Dov Borovsky, a molecular biologist at the Florida Medical Entomology Laboratory.

"It works on all mosquitoes all over the world."

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The mosquito menace is not restricted to developing countries. Mosquito watchers in Florida went on alert last August when a boy bitten by one of these most persistent of insects was hospitalised for encephalitis, an infection that causes inflammation of the brain.

Ireland should not be complacent about its near mosquito-free status. Global warming is extending the mosquito habitat and our streams, fens and lakes offer a perfect breeding ground should warmer weather eventually reach us.

Humans are losing the mosquito wars around the world, as anyone who has been bitten while abroad can confirm. There are more than 3,000 species and worldwide they infect about 700 million people each year. These diseases cause about three million deaths annually, according to figures from the US Centres for Disease Control.

Dr Borovsky's recipe for mosquito death easily beats the insecticides it would replace in that it is highly efficient but also safe for the environment. He hopes to have it available on the market within a year and he is willing to share his discovery with anyone interested.

It starts with 100,000 mosquito ovaries, dried and crushed into a powder to concentrate a digestive control hormone. This is combined with green pond scum, an algae called chlorella, particularly favoured by feasting mosquito larvae.

When the larvae ate the doctored chlorella they were unable to produce eggs as adults, leading Dr Borovsky to believe he had developed mosquito birth control. "But then we found that the reason they were not producing eggs was because they were not digesting, so then we knew we had a diet pill, not a birth control pill."

The hormone was chemically synthesised, eliminating the need to perform microsurgery on mosquitoes to recover ovaries. It is cheap to produce and chlorella is also found around the world so the recipe ingredients are readily available.

It causes the bug to starve to death within 72 hours, preventing it from getting to the point of laying eggs. "It's a natural bullet that we can use in the environment because the hormone doesn't stay in the environment," Dr Borovsky said. The chlorella is not genetically modified to produce the hormone, it carries the hormone for about three cell divisions before it fades away.

"Ten years ago, everybody was laughing at us, but now they are taking us seriously," he said. The next step is to develop diet pills for other agricultural pests.

Dick Ahlstrom

Dick Ahlstrom

Dick Ahlstrom, a contributor to The Irish Times, is the newspaper's former Science Editor.