A British company will soon carry out an intriguing experiment that should harm the development of female larvae and thus help us in the fight against the most dangerous animal in the world
By: Yael Mor, Angle - news agency for science and the environment
One of the constant annoyances of the summer, besides the heat and humidity, are the mosquitoes. This small, humming and elusive creature that pesters us wins the title of "the deadliest animal in the world", year after year. As of today, mosquitoes are responsible for about 750 deaths per year (of which about 440 are from malaria) and this by transferring various diseases from animals to humans and between humans. Therefore, researchers are constantly trying to find ways to reduce the contact between mosquitoes and humans.
Currently, the group of mosquitoes best known as disease spreaders is the Aedes group, which includes several species with a high potential for disease transmission (Zika, yellow fever, dengue fever, chikungunya and more). The mechanism of transmission of the disease takes place during the bite, when the female mosquito sucks the blood of the mammals in order to obtain proteins necessary for the development of her eggs. In this operation, the mosquito injects anti-coagulants into the wound so that it can draw blood without it coagulating, and together with them viruses, parasites and disease-causing bacteria that it carries are transferred to the bitten.
At the beginning of May 2020, the United States Environmental Protection Agency (EPA) approved the British company Oxitec (Oxitec), founded in 2002, to conduct a field experiment in Monroe County in South Florida, to examine whether the population of the Egyptian Hades mosquito can be significantly reduced, through genetic engineering.
The female killers
As part of the experiment, genetically modified male mosquitoes will be released in the area. These mosquitoes carry an inherited gene that causes the death of female offspring. That is, it is a "female-killing" gene, which prevents the development of female larval eggs. The male offspring survive and become fully functioning adults, who carry the same genetic change, which they will pass on to their offspring - and so on.
According to the plan, this genetic change could eventually lead to a significant decrease in the mosquito population in the release areas and because the male mosquitoes do not bite, they will not pose a threat to public health.
According to Oxitec and the EPA, the new experiment is not expected to harm humans, animals or the natural environment in Monroe County. In fact, Oxitec says that the United States is not the first country where this technology has been tested: over the past decade, the company has carried out similar experiments in the Cayman Islands, Panama, India and Brazil, where, according to its claim, they succeeded in reducing the Aedes egyptian population in the experimental areas by about 96 percent. With the help of reducing the mosquito population, the company was able to reduce the number of dengue fever cases in the experimental area in Brazil where 5,000 residents live (Eldorado district in the city of Pirisicaba in the state of São Paulo) by about 91 percent: from 133 to only 12.
After the end of the trial in Florida in 2022, the EPA will decide whether to approve the use of this technology on a large scale.
Oxitec was acquired in 2015 by Intrexon, an American biotechnology company, in a deal worth $160 million, and in 2019 the company received a $5 million grant from the Gates Foundation of Bill and Melinda Gates.
"The Egyptian Hades, the same species on which the experiment was conducted, is the main transmitter of a number of 'important' diseases in the world" explains Dr. Ado Tzorim, ecologist, and researcher who develops approaches and working methods for an environmentally friendly interface of pests, at Ahva Academic College. "These are diseases such as yellow fever, dengue fever, Zika and chikungunya that mosquitoes are able to transmit. In the past, the Egyptian Hades was common in the country, but due to the loss of habitats during the establishment of the state (its main habitats were large water storage vessels, Y.M.) - it disappeared."
Today, the most common species of the Aedes genus in Israel is the Asian tiger (striped Aedes), an invasive species, which is a significant nuisance to the public especially in the summer season. The Asian tiger is able to carry and probably also transmit a large number of pathogens, but in Israel we are mainly worried about the possibility that it will be the basis for an outbreak of dengue and chikungunya."
However, if the Asian tiger is a potential carrier of diseases, why are we not witnessing an outbreak in Israel? "It is possible that the local Asian tiger has lost its ability to be a carrier of the disease, but it is likely that environmental factors are responsible for this, such as: the availability of patients who brought the disease to Israel and were a source of its spread, environmental conditions (such as temperature, nutrition, etc., etc.) that are suitable for the development of the pathogen in Tosha and turning it into a carrier capable of infection, conditions that affect the survival of the mosquito, its flight distances, the availability of alternative blood sources, and more," says Tzorim. "I tend to believe that it is simply a matter of luck." However, if it is indeed luck, it may run out for us in the coming years, when tourism will return to its original scope before the Corona epidemic and the potential for the import of viruses into Israel and their local distribution by the Asinian tiger will rise again.
In an article published in Nature Microbiology at the beginning of 2019, the researchers estimated that by 2050, about half of the world's population will be at risk of contracting viruses transmitted by mosquitoes, due to the effects of global climate change and the trend of most of the world's population moving to live in large cities. A warmer and more densely populated world is also a much more hospitable world for the mosquitoes that spread the diseases.
Map the health risks
As part of the expert committee convened by the Israeli Association for Ecology and Environmental Sciences in collaboration with the Ministry of Environmental Protection, the Ministry of Health and the Ministry of the Interior, during the month of May 2020, several meetings were held in which mosquito researchers from the academy, ecologists, epidemiologists, mosquito monitoring and control experts, local government and government representatives participated. The goals of the committee are to map the knowledge gaps regarding dealing with the Asian tiger mosquito and mapping the health risks it poses, monitoring the mosquito population and promoting solutions to deal with it while making the knowledge accessible to the public. The committee's conclusions, its participants hope, will be able to help implement policies at the national and local level that will help in dealing with the Asian tiger, which as of today is only a nuisance but has the potential to cause significant morbidity in the future.
"In order for local transmission of dengue, chikungunya or Zika fever to take place in Israel, the presence of mosquitoes capable of carrying and spreading the virus - which already exists in Israel (the Asian tiger) - and the presence of humans who have been infected with the same viruses are required, so mosquitoes that bite them may become carriers of the viruses And to spread them," says Dr. Adi Levy, the scientific director of the Israeli Society for Ecology and Environmental Sciences and the head of the division for environment and sustainability at Ahva Academic College. "As long as travelers from the world arrive or return to Israel from regions where the diseases are active, there is a certain chance of the development of local transmission and spread of these diseases by mosquitoes. This risk may materialize in the future as already happened in Italy in the Rome region, where there was a local outbreak of the chikungunya virus in 2017, so we need to be prepared for it. On the one hand, monitoring and treatment of the nuisance - the invading mosquito - and on the other hand, monitoring the presence of viruses in mosquitoes and targeted treatment of disease centers if and when such are created." Levy adds that "besides the dramatic expansion of the world's flights and the increase in the number of destinations in recent decades, climate change is also a significant risk factor due to the expansion of the activity time of mosquitoes with the expected continued warming and the shortening of winter, as well as their spread to more northern habitats (in the Northern Hemisphere)."
"Since this is a mosquito with a limited flight radius of 100-50 meters, part of the discussion at the expert committee dealt with ways to effectively inform the public by the authorities for the purpose of harnessing it to the monitoring effort and treating the nuisance mainly through the drying of stagnant water sources in the private areas" says Levy, who also explains that " The Asian tiger mosquito is active during the day and is capable of breeding in a variety of water sources, from puddles to buckets of water that have been forgotten outside, the bottoms of planters and flower pots and even the cork of a bottle - the treatment is therefore very simple and can easily solve a problem that many people suffer from. What needs to be done is to remove unnecessary waste and frequently empty areas where water accumulates in the private garden or on the balconies, and replace and not add water to the animals at home and outside. A joint action of the residents in a certain street or neighborhood can have a significant impact on their quality of life while reducing the nuisance and the potential health risks it entails," he says.
"Advanced technologies for dealing with the nuisance of mosquitoes, such as genetic engineering used in the Oxitech experiment, are important and should preferably be present and available in the decision-makers' toolbox (after their effectiveness and safety have been confirmed) in a situation where they will be needed, but even before that there are simpler ways to deal with the nuisance created by the tiger The Asian," emphasizes Levy. "We want to see how, by making knowledge accessible to the public and harnessing it by the local government while allocating resources for joint action, under the guidance of the professional level in the government, it will be possible to monitor and reduce the hazard and the risks inherent in it."
More of the topic in Hayadan:
4 תגובות
Moshe, what is your last name? I might know you
The most dangerous and deadly animal in the world... is Homo sapiens. It has so far exterminated half of the animals and plants on the planet. Most of the other half is in danger of extinction.
It is certain that mosquitoes play a very important ecological role. Reducing the mosquito population, or eliminating them, will certainly cause heavy damage. After all, the system was not designed to serve the comfort of one creature (and the most unnecessary of all).
The animal and plant world should last 150-200 years. After that the creature that kills and abuses everything else will disappear and all the animals and plants and micro-organisms will be able to thrive, as they were meant to do
It is important
And it is hoped that the experiments to moderate the development of mosquitoes will be successful,
Only when it says:
"The group of mosquitoes best known as disease spreaders
is the Hades group', this is 'less than half the truth',
Because the "ads" do cause a series of serious diseases
But the Anopheles species transmit the fever parasites (malaria)
which is the main cause of death in most of the world,
Even according to the article, every year 440 thousand die from malaria
And of the diseases transmitted by Hades 310.
The difference is that fever has treatment and prevention
And the distribution of Hades mosquitoes and the (less well-known) diseases
which he distributes has been expanding only in recent decades
That is why Hades was less known until the last few years
And there was less reference to the diseases it spreads.
Until the recent period, most of the studies and attempts at extermination
Concentrate on Anopheles, which also in Israel was a risk for
Settlers in the renewed Israeli period...
Greetings,
As always, I eagerly read your interesting articles.
Unfortunately, this time there was a mistake in the article. Although in the title you mentioned mosquitoes, but throughout the article you wrote mosquitoes.
Of course, these are only mosquitoes that suck blood for reproduction.
Mosquitoes drink flower nectar.
In the spirit of strictness that blows in our time on male and female, I would be happy if you would correct the article,
As you would correct if there was an opposite error.
in good health