A venom-filled fungus with mosquito-killing abilities could provide a safe, cheap and accessible protection against malaria. In experiments, the genetically-modified fungus, which produces a toxin based on spider venom, killed over 99 per cent of mosquitoes in only 45 days.
The modified fungus Metarhizium pingshaense was first developed in 2017, but this is the first time its ability to kill mosquitoes were tested outside the lab. The team, a collaboration between scientists from the University of Maryland and Burkina Faso, tested the fungus in a 600 square-metre enclosed simulated village. When the mosquitoes were exposed to the fungus, the population dropped from 1,500 adults down to only 13. At such low numbers, the males can’t form the mating swarm required for breeding.
The scientists took advantage of a natural characteristic of the fungus: it has a ‘genetic switch’ which is only activated when it is in the bloodstream of a mosquito.
“These fungi are very selective,” said Raymond St. Leger, professor of entomology at the University of Maryland. “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. When this fungus detects that it is on a mosquito, it penetrates the mosquito’s cuticle and enters the insect. It won’t go to that trouble for other insects, so it’s quite safe for beneficial species such as honeybees.”
The team believe that the fungi could provide a realistic form of protection against mosquitoes for many communities, since the fungus is administered in sesame oil coated onto black cotton sheets, both of which can be obtained cheaply and locally. What’s more, the treatment is equally effective against mosquitoes which have developed insecticide resistance.
Next, the team hopes to carry out trials in a real village.