Mosquitoes transmit the parasite, Plasmodium, that causes malaria, one the deadliest diseases on Earth. Recent research could turn the tables on the mosquitoes by using fungal parasites to kill them before they can do any damage.
Some species of fungus feed on the mosquitoes before they even develop into their flying stage. Mosquitoes live in the water before turning into buzzing blood suckers. By using the fungus to kill off mosquito larvae in the water, the insects never get a chance to infect anyone with malaria.
Research has shown that the fungi, Metarhizium anisopliae and Beauveria bassiana, are effective controls against mosquitoes, since the insects aren’t repelled by the presence of fungal spores in the water. The insects unwittingly lay their eggs in water infected with the fungal spores, according to research published last year in Parasites and Vectors. Once the mosquito larvae hatch, many are doomed to infection and death by the fungi.
The question was how to apply the fungal spores to the water evenly to ensure uniform coverage, and still be environmentally safe.
Recent research by Tullu Bukhari and his colleagues at Wageningen University in the Netherlands found a way to use a synthetic oil to improve the dispersal of fungal spores over the surface of water. The combination of oil and fungal spores killed up to 50 percent more mosquito larvae than untreated spores. This reduced the number of mosquitoes turning into adults, or pupating, to less that 20 percent at test sites in Kenya.
“These fungi provide an effective means of controlling malaria mosquitoes. Both spores and the oil have minimal risk to fish and aquatic organisms and so are also environmentally safe,” said Bukhari in a press release by BioMed Central, publishers of Parasites and Vectors, the journal where Bukhari’s research was published.
Killing the mosquitoes themselves through natural means solves some of the problems facing malaria control. The mosquitoes are less likely to develop resistance to the fungus than insecticides.
The malaria causing parasite, Plasmodium, has already developed resistance to chemical treatments. So by killing the mosquitoes, even the drug-resistance parasites never get a chance to infect people.
Finding new ways to reduce mosquito populations and thereby prevent malaria could reduce the suffering and death of millions. The World Health Organization reports that 247 million cases of malaria were reported in 2008.
Nearly one million of those malaria cases resulted in death, mostly of children in the tropical regions of the developing world. Malaria accounts for 20 percent of all childhood deaths in Africa, such that an African child dies every 45 seconds from the disease.
A mosquito of the species Culex quinquefasciatus, one of the varieties controllable by fungus (Wikimedia Commons)
A mosquito larvae; (Wikimedia Commons)