AFP
NOS News•
Yellow fever mosquitoes have been discovered in Vietnam and Cambodia that are extremely resistant to the toughest insecticides. Japanese researchers write this in the scientific journal Science Advances. 78 percent of the mosquitoes studied have been genetically modified in such a way that they are well protected against the most commonly used pesticides, which is of great concern to scientists.
The mosquito species in question is the Aedes aegypti, which, in addition to yellow fever, also spreads infectious diseases such as dengue (dengue fever), Zika and chikungunya. The researchers discovered ten new substrains of this mosquito with a mutation. One of those mutations – called L982W – occurred in 78 percent of the mosquitoes. In one specific region in Cambodia, as many as 90 percent of mosquitoes had the mutation.
In the labs, the mosquitoes with this mutation, or a combination of other gene mutations, proved much more difficult to kill with pyrethroids, the pesticide most commonly used against mosquitoes. Even against greatly increased doses of the drug, these “super-resistant mosquitoes” coped better than researchers have ever observed.
21,000 deaths
“It is worrying that this is being seen, but also not surprising given our great dependence on that group of pesticides for control,” says Associate Professor of Medical and Veterinary Entomology Sander Koenraadt of Wageningen University in the NOS Radio 1 Journal. “The more those pesticides are used, the more resistance mosquitoes develop.”
Dengue fever is a major problem worldwide, Koenraadt continues. “More than 400 million people contract this infection. There are still 21,000 estimated deaths every year. Local governments in Asia and South America in particular are at a loss because you see outbreaks of this disease every year.”
The yellow fever mosquito originates from Africa and is now also found in the tropical regions of Asia, South and Central America. The area where the mosquito occurs has grown in recent years and experts previously warned that the insect could cover an even larger area due to climate change.
Make mosquitoes infertile
“If indeed almost 80 percent of the mosquitoes are insensitive, then those mosquitoes will continue to fly around and continue to spread that disease,” says Koenraadt, who points out that it is precisely for this reason that alternatives to insecticides are being sought. “There is also a particular focus on non-chemical agents.”
Examples of non-chemical pesticides with which there are good experiences are mosquito traps, which can be used on a large scale. “And, for example, the use of the Wolbachia bacteria is also on the rise. It is also being tested on a larger scale. The idea behind this is that you release mosquitoes and thus cause sterility in the population. Those mosquitoes can then no longer have offspring, so that they populations collapse,” says Koenraadt.
Another alternative against dengue is vaccination. “There are also initiatives to develop a vaccine against dengue and thus protect people against infection.”