Latest news with #A.aegypti
Yahoo
02-05-2025
- Health
- Yahoo
What would a world without mosquitoes look like?
In 1958, the Pan American Health Organization (PAHO) made a milestone announcement: they had exterminated the mosquito Aedes aegypti–a transmitter of the deadly diseases dengue, chikungunya, and yellow fever–from Brazil. This represented the culmination of decades of work. In the 1930s, an ambitious inspection regime removed any sources of stagnant water–key mosquito breeding grounds–in areas where A. aegypti had been detected. Authorities eased this onerous system in the years after World War II as they found success in wiping out mosquitoes with a new weapon: the insecticide DDT. PAHO didn't stop at the Brazilian border; by the mid-1970s, Argentina, Bolivia, Chile, and Paraguay were among nine South and Central American countries to have eradicated A. aegypti. This had significant epidemiological impacts: dengue and other conditions virtually disappeared from the DDT-soaked countries, and the specter of these conditions retreated from the continent. Unfortunately, the story was far from over. Mosquito control efforts failed to account for how persistent A. aegypti could be. It was never eradicated from Columbia or Guyuna. Within just a few decades of PAHO's declaration, dengue re-emerged. Worse still, DDT, PAHO's bug spray of choice, was revealed to have horrific effects on biodiversity in sprayed environments. Public sentiment turned against this indiscriminate tool after the publication of books like Rachel Carson's Silent Spring. Fast-forward to today. Last year was one of the worst on record for dengue in South America in the face of a resurgent A. aegypti. New mosquito-borne diseases like Zika have emerged. The dream of a pest-free South America is further away than ever. However, the goal of squashing mosquito-borne diseases is still paramount for Scott O'Neill, CEO of the World Mosquito Program, a network of companies spun out of Monash University. O'Neill explains that his program aims not to suppress mosquitoes but to help them fight the viruses that infect them and turn them into disease vectors. The WMP's approach involves the symbiotic bacterium Wolbachia. 'Around 50 percent of all insects naturally have Wolbachia,' explains O'Neill. The bacterium cannot survive outside hosts' bodies and infects many organs in A. aegypti. The WMP breeds huge populations of mosquitoes infected with Wolbachia and releases them into the environment. Inside A. aegypti mosquitoes, disease-causing viruses also exploit their hosts' cells to reproduce. O'Neill aims to create a population of mosquitoes in which these viruses have to compete with Wolbachia. Fighting Wolbachia inside an insect is like trying to arm wrestle a polar bear in a Siberian snowstorm. The bacterium has developed various ingenious tools to make itself the dominant symbiote. O'Neill explains that it alters the lipid profile inside mosquitoes' cells, making it harder for them to reproduce. It even boosts the antiviral responses of the A. aegypti immune system, helping the mosquito fight off its competitors. [Related: ] No further intervention is needed after the initial injection of Wolbachia-infected insects. Over time, Wolbachia will naturally spread through the mosquito population and the number of bugs that can become infected with viruses declines. WMP say this approach has slashed rates of dengue in Australia and Columbia. In a controlled trial in Indonesia, the technique reduced virologically confirmed dengue by 77 percent. If A. aegypti was somehow wiped from existence, it wouldn't significantly harm the ecosystems it lives in, says O'Neill. That's because it largely ignores environments where other animals live, unlike other species of mosquitoes that are food sources for frogs and fish. 'It lives in cities, and it's exquisitely adapted to biting humans,' says O'Neill. Some scientists suggest that if every mosquito species were to disappear, there would be significant impacts on bird populations. However, this is contested by other researchers who say they aren't an irreplaceable part of these birds' diet. Some mosquitoes are pollinators, although very few plant species are only pollinated by mosquitoes. In short, the loss of all mosquito species would be felt by ecosystems, but to a much lesser extent than the loss of vital pollinators like the honey bee. Our efforts to remove even one ecologically unimportant mosquito species have fallen short for now. O'Neill says that entomologists call A. aegypti the 'cockroach of the mosquito world' for good reason, and its tenacity and widespread range mean that we are unlikely to see a world without this buzzing pest any time soon. This story is part of Popular Science's Ask Us Anything series, where we answer your most outlandish, mind-burning questions, from the ordinary to the off-the-wall. Have something you've always wanted to know? Ask us.
The Guardian
25-02-2025
- Health
- The Guardian
Scientists worried about CSIRO-backed plan to release genetically modified mosquitos in Queensland
A CSIRO-backed plan to release genetically modified mosquitoes in Queensland to combat dengue fever has sparked concern from scientists who suggest it could interfere with successful control programs and increase the risk of insecticide resistance. Oxitec Australia, a collaboration between a British biotechnology firm and the CSIRO, has applied to sell a GM strain of Aedes aegypti mosquito, the main culprit for transmitting dengue and other viruses. The strain, called OX5034 A. aegypti, prevents female mosquitoes from surviving into adulthood. Only female mosquitoes bite, spreading diseases to animals in the process. Sign up for Guardian Australia's breaking news email Oxitec is proposing to sell the mosquitoes for Queensland residents to release. After release, they would breed with local A. aegypti mozzies, reducing populations. An Oxitec Australia spokesperson said the sale of the strain would 'be available to protect Australian communities' and released only after it passed 'stringent government and regulatory approvals and undergoes extensive community engagement and consultation'. But mosquito experts have criticised the proposal. 'We should be very concerned about this release going ahead as planned,' Dr Perran Ross, a scientist at the University of Melbourne who worked on mosquitoes for more than a decade, said. 'I'm not opposed to the [GM] technology in general but I am opposed to the approach they're using, taking a foreign mosquito strain and then releasing that straight into the wild.' The OX5034 strain is engineered from mosquitoes originating from Mexico. Though Oxitec has conducted field trials in the United States, and Brazil, where the strain is commercially available, releases have not yet been tested in Australia. Australian mosquitoes are uniquely susceptible to insecticides such as pyrethroids, Ross said. 'There's insecticide resistance almost everywhere else in the world. If you're releasing a mosquito strain from a different country … there's that risk that it might introduce genes that cause insecticide resistance.' Climate adaptation was another concern, Ross said. 'If you take mosquitoes from Mexico and bring them to Australia, you might get some genes that make them more tolerant to dry climates or other conditions. We don't really know what the effect of that is going to be, but it is a potential risk.' There are also concerns the Oxitec mosquitoes could interfere with success of Wolbachia programs, which have virtually eliminated dengue in far north Queensland. Since 2011, mosquitoes infected with naturally occurring Wolbachia bacteria have been released in the state's north as part of a World Mosquito Program initiative. The Wolbachia prevents the mosquitoes from transmitting viruses. 'Wolbachia has eliminated dengue as a public health problem over the last decade there,' said Prof Cameron Simmons, executive director of global delivery at the World Mosquito Program. 'I can't see anyone spending public funds, or even really private funds, to suppress A. aegypti mosquitoes with Oxitec GMO mosquitoes in far north Queensland.' Ross said: 'My major concern is the interference with the Wolbachia approach. 'They have very different objectives: the Wolbachia approach doesn't aim to wipe out populations, it's only replacing them with ones that don't spread dengue as well. 'The GM mosquitoes are going to actually compete and wipe those ones out.' A spokesperson for Oxitec Australia said: 'There is no scientific evidence to suggest that there would be any negative interaction with mosquitoes that carry Wolbachia … We are committed to applying robust and transparent scientific processes to ensure that this technology is tested and is safe for deployment.' Oxitec Australia has applied to the Office of the Gene Technology Regulator for a licence for commercial release. Public consultation on the proposal is expected to open in March; a public petition opposing the proposal was tabled in Queensland parliament last week. Oxitec Australia says its mosquitoes could provide 'an extra level of protection against dengue' in areas where Wolbachia has not been introduced – such as the Torres Strait, where there was an outbreak late last year – and 'further reduc[e] the risk of dengue in areas where Wolbachia is present.' Addressing insecticide concerns, Oxitec says its 'Aedes aegypti mosquitoes have been proven to dilute resistance to insecticides among wild mosquito populations'. 'Oxitec's technology is also sustainable, chemical-free, highly effective, and harmless to non-target species including mosquito predators,' a spokesperson said. It will reduce dependence on pesticide-based controls, lowering environmental impacts and therefore help to protect native mosquitoes and other insect species like pollinators.'
