Malaria mosquitoes eliminated in lab by creating all-male populations

MAY 12, 2020

by Hayley Dunning, Imperial College London

A modification that creates more male offspring was able to eliminate populations of malaria mosquitoes in lab experiments.

A team led by Imperial College London spread a genetic modification that distorts the sex ratio through a population of caged Anopheles gambiae mosquitoes using 'gene drive' technology.

The team's modification causes mosquitoes to produce more male offspring, eventually leading to no females being born and a total collapse in the population. This represents the first successful sex-distorter gene drive ever created, a goal for scientists as these modifications are expected to be extremely effective at controlling natural mosquito populations.

There were 228 million cases of malaria in 2018, and 405,000 deaths, with new interventions needed to move towards malaria eradication. There are around 3500 species of mosquito worldwide, of which only 40 related species can carry malaria. The team's modification was applied to Anopheles gambiae mosquitoes, the main malaria vector in sub-Saharan Africa.

The hope is that Anopheles gambiae mosquitoes carrying a sex-distorter gene drive would be released in the future, spreading the male bias within local malaria-carrying mosquito populations and causing them to collapse.

As only females bite and take blood meals, only they can pass on malaria, so the modification could have a double effect by biasing the population towards fewer females even before the population collapses.

The lab-based experiments were performed with caged populations of mosquitoes, and more experiments are needed before the team consider releasing any modified mosquitoes in the wild. The results are published today in Nature Biotechnology.

Lead scientist Professor Andrea Crisanti, from the Department of Life Sciences at Imperial, said: "This study represents a key milestone in the long-sought objective to bias the progeny of the human malaria mosquito so that only non-biting males are produced. Having a proven driving sex-distorter opens a new avenue for scientists to develop genetic vector controls of malaria with the aim of eradicating the disease."

Read on

Mosquitoes infected with bacteria to make them infertile released in battle against viruses

When the released males mate with wild female mosquitoes, the resulting eggs will not hatch 

Mythili Sampathkumar New York 

Wednesday 31 January 2018 21:40 GMT

In order to fight Zika and other similar viruses, researchers are going to release thousands of sterilised mosquitoes in south Miami, Florida this week.

Researchers infected the male of the species with a bacteria in a lab and when they mate with females, the resulting eggs will die before hatching.

The Miami-Dade County Mosquito Reduction Test Program is a collaboration from the University of Kentucky and Kentucky-based company MosquitoMate.

The project is an attempt to reduce mosquito populations in the region without artificial genetic modification.

The bacteria used to infect the males, wolbachia, is a naturally-occurring substance in 60 per cent of insects including butterflies and dragonflies.

It is not harmful to humans.

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Mosquitoes more likely to lay eggs in water sources near flowers

Date:January 5, 2016

Source:Entomological Society of America

Certain mosquitoes are more likely to lay eggs in water sources near flowers than in water sources without flowers, according to an article published in the Journal of Medical Entomology.

Researchers from the USDA and the University of Florida studied the Asian tiger mosquito (Aedes albopictus) and its egg-laying preferences. This mosquito is known to transmit yellow fever, dengue, and chikungunya, and it has been spreading throughout the United States.

Asian tiger mosquitoes prefer to lay eggs in containers, so the first thing the scientists decided to test was whether the size of the containers made any difference. They were also curious about whether or not the presence of flowers might affect the egg-laying behavior, due to the fact that mosquitoes drink nectar from flowers.

The researchers studied female mosquitoes that had been fed bloodmeals and released in large cages with water containers flowering buttterfly bushes (Buddleja davidii).

They found significantly more eggs in the largest containers, and they found more eggs in containers next to flowering bushes than in containers without flowers.

These findings could lead to new methods of controlling the mosquito.

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As Greenland warms, blood-thirsty mosquitoes thrive

SEPTEMBER 16, 2015

by Eric Hopton

They’re hungry, aggressive, desperate, and on the hunt for a “blood meal”. Arctic mosquito populations are taking advantage of global warming and breeding like crazy, and the big increase in mosquito numbers is threatening the survival of the poor caribou of Greenland.

Lauren Culler, an ecologist with Dartmouth’s Institute of Arctic Studies, has been studying Greenland’s mosquitoes, and according to Culler, only 12-15 percent of mosquitoes ever get that all important blood meal—but that’s enough for the species to multiply.

Blame the ladies

As Cullen told Motherboard, only female mosquitoes bite and need a blood feast to reproduce, but it's the higher Arctic temperatures are allowing more mosquitoes to survive and become adults.

The problems start when caribou make their spring migration to feed on new plant growth and give birth to their calves. When they get to the spring pastures, they find the plants have blossomed early in the warmer climate and are already well past their “sell by date”.

The mosquitoes too have cashed in on warmer springs to mature earlier and are just waiting for a mobile blood bank in the form of a caribou, musk ox, or maybe the odd human or two. Understandably, the caribou try to avoid the mosquitoes and head into the hills where cooler temperatures and stronger winds reduce the mosquito threat. Sadly, that uses up energy and feeding time as well as taking them away from their richest food source.

Read more at

How mosquitoes zero in on warm bodies

By Jonathan WebbScience reporter, BBC News

16 July 2015 

New research suggests that mosquitoes track down something to bite using a sequence of three cues: smell, then sight, and finally heat.

Biologists recorded the movement of hungry mosquitoes inside a wind tunnel.

The insects were instantly attracted to a plume of CO2, much like a human breath; after sniffing this gas they would also home in on a black spot.

Finally, over much shorter distances, the mosquitoes were also drawn towards warmth.

The findings, published in the journal Current Biology, build on previous evidence that smell is crucial for mosquitoes to pinpoint their next meal.

Body odour, for example, may play a role in how they choose one victim over another.

But mosquitoes are particularly good at sniffing out CO2, which is highly concentrated in the breath of the animals whose blood they feed on - like humans. Mosquitoes can home in on stale, exhaled air from up to 50m away.

It was also known that heat and vision could be important for attracting the blood suckers, but the new study is the first to unpick the distinct role of all three cues.

"We were able to put together a working theory for how all these senses work together in the mosquito, to find a human," said first author Floris van Breugel, from the California Institute of Technology.

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Brazil releases 'good' mosquitoes to fight dengue fever

24 September 2014 Last updated at 22:38

Brazilian researchers in Rio de Janeiro have released thousands of mosquitoes infected with bacteria that suppress dengue fever.

The hope is they will multiply, breed and become the majority of mosquitoes, thus reducing cases of the disease.

The initiative is part of a programme also taking place in Australia, Vietnam and Indonesia.

The intracellular bacteria, Wolbachia, being introduced cannot be transmitted to humans.

The programme started in 2012 says Luciano Moreira of the Brazilian research institute Fiocruz, who is leading the project in Brazil .

"Our teams performed weekly visits to the four neighbourhoods in Rio being targeted. Mosquitoes were analysed after collection in special traps.

"Transparency and proper information for the households is a priority. "

Ten thousand mosquitoes will be released each month for four months with the first release in Tubiacanga, in the north of Rio.

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Malaria-carrying mosquitoes wiped out in lab with genetic method that creates male-only offspring

Date:

June 10, 2014

Source:

Imperial College London

Summary:

Scientists have modified mosquitoes to produce sperm that will only create males, pioneering a fresh approach to eradicating malaria. Since 2000, increased prevention and control measures have reduced global malaria mortality rates by 42 per cent, but the disease remains a prevalent killer especially in vulnerable sub-Saharan African regions. Malaria control has also been threatened by the spread of insecticide resistant mosquitoes and malaria parasites resistant to drugs.

Continued

Peoria Ag Lab works to control world's deadliest animal

By Steve Tarter of the Journal Star 

Posted Apr. 26, 2014 @ 10:35 pm 

Mosquitoes kill 1 million people each year, according to the World Health Organization, making it the deadliest animal in the world.

A Peoria scientist at the Ag Lab is at the forefront of a war against this killer.

Scientist Alejandro Rooney is engaged in new research efforts to battle dangerous mosquito varieties such as the Asian Tiger, yellow fever and floodwater species at the Peoria Ag Lab.

“Mosquitoes carry some nasty diseases — like dengue fever, chikungunya and West Nile Virus,” said Rooney, the research leader of the crop bioprotection unit at the U.S. Department of Agriculture lab at 1815 N. University St.

“There’s also the treehole mosquito that can spread encephalitis,” he said, adding that mosquitoes also pose a threat to livestock.

It’s enough to call off summer and pray for the return of the Polar Vortex.

Read more:

Nazis 'wanted to use mosquitoes as a weapon'

UPDATE: Nazi scientists worked on ways to use malaria-carrying mosquitoes as a weapon, according to researchers. Until now, experts have disputed whether Germany was working on biological warfare during World War II.

Dr Klaus Reinhardt, who led the study, told The Local that he came across documents at Dachau's Entomology Institute which suggested that “biological weapons [using mosquitoes] could have been developed as an offensive, not defensive, weapon”.

Until now, it had been generally thought by experts that the Nazis only intended ever to use biological weapons defensively.

By 1944 the institute had decided on a specific breed of mosquito most suited to a potential biological attack, said Reinhardt.

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Toward Making People Invisible to Mosquitoes

Sep. 9, 2013 — In an advance toward providing mosquito-plagued people, pets and livestock with an invisibility cloak against these blood-sucking insects, scientists today described discovery of substances that occur naturally on human skin and block mosquitoes' ability to smell and target their victims.

Ulrich Bernier, Ph.D., who gave the talk, cited the pressing need for better ways to combat mosquitoes. Far from being just a nuisance, mosquitoes are more deadly to humans than any other animal. Their bites transmit malaria and other diseases that kill an estimated one million people around the world each year. In the United States, mosquitoes spread rare types of encephalitis, an inflammation of the brain. They also transmit heart worms to pet dogs and cats.

"Repellents have been the mainstay for preventing mosquito bites," said Bernier. "The most widely used repellant, DEET, is quite effective and has been in use for a long time. However, some people don't like the feel or the smell of DEET. We are exploring a different approach, with substances that impair the mosquito's sense of smell. If a mosquito can't sense that dinner is ready, there will be no buzzing, no landing and no bite."

Female mosquitoes, which suck blood to obtain a protein needed to produce fertile eggs, can smell people from over 100 feet away. The Mosquito and Fly Unit at the U.S. Department of Agriculture's Agricultural Research Service-Center for Medical, Agricultural, and Veterinary Entomology in Gainesville, Fla., has been doing research on mosquito repellents since the 1940s. In the 1990s, they accumulated information on substances secreted through the human skin or formed by bacteria on the skin that make some people more attractive to mosquitoes than others.

Continued

Meet the Gallinippers: Huge Mosquitoes Spotted in Florida

Enormous mosquitoes known as gallinippers (or Psorophora ciliata) have been spotted in Florida, according to WKMG, a CBS affiliate. The insects are about 20 times larger than most common mosquitoes. The sighting comes after a warning by the University of Florida that there could be a bumper crop of these mosquitoes this summer.

Gallinippers can grow to the size a quarter and have painful stings, which can feel "like you're being stabbed," Anthony Pelaez of Tampa's Museum of Science and Industry told Fox Orlando earlier this year. The huge insects are known to be aggressive and feed both day and night; most mosquitoes aren't active during the day.

The gallinippers depend on heavy rains and were nourished by last year's downpour from Tropical Storm Debby. Continued rainfall, like that from Tropical Storm Andrea, will likely cause a spike in all mosquitoes this summer, Kelly Deutsch, the director of Seminole County Mosquito Control, told WKMG. 

http://www.livescience.com/37383-gallinippers-huge-mosquitoes-florida.html

Genetic Engineering Alters Mosquitoes' Sense of Smell

May 29, 2013 — In one of the first successful attempts at genetically engineering mosquitoes, HHMI researchers have altered the way the insects respond to odors, including the smell of humans and the insect repellant DEET. The research not only demonstrates that mosquitoes can be genetically altered using the latest research techniques, but paves the way to understanding why the insect is so attracted to humans, and how to block that attraction. "The time has come now to do genetics in these important disease-vector insects.

I think our new work is a great example that you can do it," says Leslie Vosshall, an HHMI investigator at The Rockefeller University who led the new research, published May 29, 2013 in the journal Nature.

In 2007, scientists announced the completion of the full genome sequence of Aedes aegypti, the mosquito that transmits dengue and yellow fever. A year later, when Vosshall became an HHMI investigator, she shifted the focus of her lab from Drosophilaflies to mosquitoes with the specific goal of genetically engineering the insects. Studying mosquitoes appealed to her because of their importance as disease carriers, as well as their unique attraction to humans.

Vosshall's first target: a gene called orco, which her lab had deleted in genetically engineered flies 10 years earlier. "We knew this gene was important for flies to be able to respond to the odors they respond to," says Vosshall. "And we had some hints that mosquitoes interact with smells in their environment, so it was a good bet that something would interact with orco in mosquitoes."

Read on

Malaria parasite lures mosquito to human odour

By Rebecca Morelle, Science reporter, BBC World Service

Mosquitoes carrying the malaria parasite are more attracted to human body odour than uninfected insects, a study suggests.

Researchers found that infected insects were three times more likely to be lured towards a human scent.

They believe that the deadly parasites are seizing control of their biting hosts and boosting their sense of smell.

The research is published in the journal Plos One.

Dr James Logan, from the London School of Hygiene and Tropical Medicine (LSHTM), said: "One thing that always surprises me about parasites is how clever they are. They are these ever-evolving organisms that seem to be one step ahead of us the whole time."

Smelly feet

To carry out the study, the researchers infected malaria mosquitoes (Anopheles gambiae) with the most deadly form of parasite, Plasmodium falciparum.

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West Nile Virus Spreading Due to Mosquitoes in Orchards and Vineyards, Experts Warn

Jan. 30, 2013 — Washington State University researchers have linked orchards and vineyards with a greater prevalence of West Nile virus in mosquitoes and the insects' ability to spread the virus to birds, horses and people.

The finding, reported in the latest issue of the journal PLOS ONE, is the most finely scaled look at the interplay between land use and the virus's activity in key hosts. By giving a more detailed description of how the disease moves across the landscape, the study opens the door to management efforts that might bring the disease under control, says David Crowder, a WSU entomologist and the paper's lead author.

Since it was first seen in New York in 1999, West Nile virus has reached across the country and shown few signs of abating. Last year, the U.S. Centers for Disease Control had the highest number of reported cases -- 5,387, including 243 deaths -- since 2003.

Roughly one in five infected people experience a fever, headache, body aches and, in some cases, a skin rash and swollen lymph glands. One in 150 people can get a high fever, headache, neck stiffness, disorientation and neurological problems.

Continued:  http://www.sciencedaily.com/releases/2013/01/130130184318.htm

Officials urge horse owners to vaccinate against West Nile virus

DES MOINES, Iowa (AP) — Iowa agriculture and health officials are warning that mosquitoes are still active in the state and are urging horse owners to have the animals vaccinated against West Nile virus.

The Iowa Department of Agriculture and Land Stewardship and Iowa Department of Public Health said in a joint statement that mosquitoes can carry West Nile virus until the first hard freeze.

Officials say surveillance has shown a larger number of horses have been infected with West Nile virus this year, with more than 20 confirmed cases. Last year, Iowa only had one confirmed case in a horse.

West Nile virus is transmitted through the bite of a mosquito that has picked up the virus from an infected bird. The virus has flu-like symptoms.

http://www.desmoinesregister.com/viewart/20120929/BUSINESS01/120929009/Officials-urge-horse-owners-vaccinate-against-West-Nile-virus

Influx of mosquitoes in South West

Some areas in the South West are in the grip of a mosquito plague caused by the persistent wet weather, experts have warned.

The recent heavy rainfall and flooding, combined with mild temperatures, has left many parts of the Westcountry covered with stagnant water.

This has created the perfect breeding ground for mosquitoes, which are now plaguing large swathes of the countryside.

On Twitter, @Cartmanisa wrote: “Got eaten alive in Appledore last week at a camp site 1 evening. Had 23 bites around feet & ankles-only bits exposed! Still sore.”

The Somerset Levels have been particularly hard-hit, with some residents forced to sleep under mosquito nets to avoid being bitten during the night.

One man claimed he had been bitten up to 40 times in one night.

Dr Derric Nimmo, head of public health at Oxitec - a biotech company which specialises in tackling pest diseases - said the current situation is unprecedented.

He said: "This summer has been very odd with its weather patterns and there has been flooding all over the country.

"More rain means more breeding sites. It has been relatively warm so mosquitoes have been able to breed quicker.

"It is very uncommon and it seems to be affecting the whole country.”

Have you noticed an influx of mosquitos in North Devon? Contact newsdesk on 01271 347432 or email emma.glanfield@northcliffedigital.co.uk.

http://www.thisisnorthdevon.co.uk/Influx-mosquitoes-South-West/story-16664562-detail/story.html

Future Dengue Forecast: Intricate Relationships Between Mosquitoes, Virus and Climate Change Found

ScienceDaily (July 5, 2012) — Dengue fever most likely will become a disease the United States must learn to live with as climate change creates opportunities for the disease to gain a foothold.

But after careful study of the disease's characteristics, the mosquitoes that carry it and future climate change, two researchers at Texas Tech University said the impact on areas likely to experience dengue won't necessarily play out along the lines of conventional wisdom.

Their findings were published July 5 in Environmental Research Letters.

Many studies have looked at how climate change might alter the geographic range of the mosquito-borne disease and assume the disease will occur wherever mosquitoes that carry it are found. This generally leads to predictions that the disease will move northward as the climate warms.

However, Texas Tech researchers dug deeper to study climate constraints on the geographic range of the mosquito that carries dengue and the incubation characteristics of the disease within the mosquito. Factoring these into the equation, they found Southern outbreaks would decrease in size overall and become more common in the spring and fall while Northern areas could experience larger outbreaks throughout the summer.

Continued:  http://www.sciencedaily.com/releases/2012/07/120705151204.htm

State Resumes West Nile Virus Testing as Mosquitos Return

State health officials are asking the public to be on the alert for reporting dead birds possibly linked to a West Nile Virus outbreak.

Sunny days and warmer temperatures make way for lots of outdoor activities. It’s also mosquito season, which increases the risk for West Nile virus and the need to avoid mosquito bites.

The state Department of Health has resumed tracking the rare but potentially deadly virus with an online dead bird reporting system that the public can use to alert authorities to potential health hazards. Two such birds were discovered to have died from the virus and found by the residents in King County in 2009.

“It’s important to track West Nile virus so people have the information they need to avoid getting sick,” said Maryanne Guichard, assistant secretary for the state Department of Health’s environmental public health division. “This system helps show where West Nile virus activity is in our state. It also lends a hand to counties where resources are limited.”

Locating and testing dead birds is one way to track West Nile virus since it’s primarily a disease of birds — especially crows, ravens, jays, magpies, and hawks. These birds often die when infected with West Nile virus. The Department of Health asks people to watch for dead birds and report them online or contact their local health agency. Dead bird monitoring is encouraged from May through November.

Continued:  http://mercerisland.patch.com/articles/state-resumes-west-nile-virus-testing-as-mosquitos-return

Dead birds to be accepted earlier for West Nile testing

SPRINGFIELD — All that warm, summerlike weather in March could bring an early start to mosquitoes carrying West Nile virus, state health officials say.

So state labs will begin accepting dead birds for testing two weeks earlier than usual, beginning on Monday, instead of waiting until May 1.

A dead bird can signal West Nile virus is present in the vicinity, because the virus is spread through the bites of mosquitoes feeding on infected birds.

Last year, the virus first turned up in Illinois on June 8 through two birds that tested positive from LaSalle County, and it was present in 19 counties in all, according to the Illinois Department of Public Health.

There were 34 people from Illinois who were sickened by the virus last year, and three who died from it, the health department said.

State labs will test mosquito batches, dead crows, blue jays, robins and other perching birds, as well as samples from sick horses and humans with West Nile-like disease symptoms.

Only 20 percent of people infected with West Nile virus will develop symptoms, which can include nausea, fever, headache and muscle aches, health experts say. But in rare cases, serious illness and death can occur, with people over 50 being at the highest risk.

Jeff Blackford, an environmental health program coordinator at the Champaign-Urbana Public Health District, said the district was able to submit 10 birds for testing from Champaign County last year.

Dead birds subject for testing should appear to have died within the last 48 hours, be free of decomposition, dry eyes and scavenging animals. And they should not appear to have been shot or run over by a vehicle, he said.

Anyone wishing to report a dead bird for investigation should call the environmental health division at 373-7900, he said.

The Ford-Iroquois Health Department is asking people finding dead birds (intact and dead for less than 24 hours) to double-bag them and bring them to the health department offices at 235 N. Taft St., Paxton, or 114 N. Third St., Watseka.

http://www.news-gazette.com/news/health/health-care/2012-04-14/dead-birds-be-accepted-earlier-west-nile-testing.html