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Scientists have modified a fungus to contain a gene derived from the venom of a spider intended to kill mosquitoes carrying malaria in West Africa. Genetic duplicity has worked, with most mosquitoes dead in two generations.
Billions of people live in areas where mosquito-borne diseases are a real and present danger. The World Health Organization (WHO) estimates that more than 200 million cases of malaria are reported each year in sub-Saharan Africa. Although other genetic modification experiments are ongoing, none resemble this one, said lead author Brian Lovett.
"No control of transgenic malaria has been conducted so far in the field trials. This document marks a big step forward and sets a precedent for this method and other transgenic methods to progress, "said Lovett, of the University of Maryland (UMD), in a statement.
The field test was conducted in a 6,550-square-foot structure with mosquito-net walls rather than glass. The laboratory, called MosquitoSphere, was located in Burkina Faso, West Africa, where more than 7.9 million cases of malaria were reported in 2017;
The team used a strain of mosquito-specific fungus and modified it to produce a toxin derived from the funnel spider blue mountains. This toxin is an EPA approved insecticide, called hybrid, already used on crops to control pests.
"You can think of the fungus as a hypodermic needle that we use to give the mosquito a powerful insect-specific toxin," said Raymond St. Leger, Professor of Entomology at UMD and co-author of the study published in the journal Science. .
"The simple application of the transgenic fungus to a leaf hanging on the wall of our study area caused mosquito populations to crash within 45 days," Lovett added. "And it's as effective at killing insecticide-resistant mosquitoes as non-resistant mosquitoes."
The next question is what happens to local insects exposed to the fungus? Preliminary tests suggest that it is not harmful to other insects such as honey bees, an indispensable species. The selective carnage is due to the fact that the toxin of the mushroom remains inactive until reaching the blood of mosquitoes.
"These mushrooms are very selective," said St. Leger. "They know where they are thanks to the chemical cues and the shape of the body features of an insect.The strain we work with likes mosquitoes.When this fungus detects that it is on a mosquito It penetrates into its cuticle and penetrates into the insect.This will not be a problem for other insects, so it is safe for useful species like bees.
In one experiment, the team applied sesame oil containing the mushroom on black cotton sheets inside the sphere. They then released over 1000 Anopheles coluzzii mosquitoes that fed on the blood of a calf. They compared the results of this population to a control population that had no fungi or fungi without modification of the toxin. In two generations, their population has reduced to only 13 adults. In another experiment, females infected with the hybrid only laid 26 eggs, compared with 139 in the control group.
The results are promising but not yet ready for field testing. Some researchers fear that the genetic engineering of the fungus will result in a trickle effect on the ecosystem. There are also regulatory hurdles to overcome before the method can be used in regions such as Burkina Faso.
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