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Mosquito physics

Mosquito physics


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What are the environmental limitations of mosquitos I should know of if I want to avoid getting bitten?

For example:

  • How fast should I walk in order to be moving too fast for one to bite me?
  • Can a fan work to blow mosquitos away from me?
  • If I'm looking to buy an apartment, is there a minimum height in which mosquitos will no longer reach?

Thanks!


Speed of mosquitoes vary from place to place and their current health status.But if there is any such problem, maybe you can run a short distance (some yards) and then they won't harass you for some time till they cope up with you.

Yeah, a fan usually at comfortable speed will be enough to blow the mosquito away. If this doesn't work then set speed at full speed and wrap yourself in a blanket

I don't think there is some height where mosquitoes can't reach but my friend who lives on 12th floor in his apartment hardly has 4-5 mosquitoes bugging him.


I am quoting this web page http://spectrum.ieee.org/consumer-electronics/gadgets/backyard-star-wars which describe a prototype of a system to kill mosquitoes by means of a LASER, for what regard the speed:

Mosquitoes fly up to a meter per second.

This speed is compatible with 1.2 meter per second quoted in the paper

SNOW, W. F. Field estimates of the flight speed of some West African mosquitoes. Annals of tropical medicine and parasitology, 1980, 74.2: 239-242.

There was a relationship between wind speed and catches of Anopheles melas and Culex thalassius which attempted to bite man at ground level and at 4 and 8 m on an open scaffolding tower, in cleared bush in The Gambia. It was expected that in winds which exceeded their flight speed, no mosquitoes would be able to approach and attack men on the tower. Catches of mosquitoes fell off sharply in winds of 120 cm/s, which may approximate to their flight speed, although some insects were still captured at the highest wind speeds encountered.

For what regard the flying altitude:

The average flying altitude varies among mosquito species but is usually only about 2 meters. They will fly over obstacles when necessary-even into an upper-story window-but if your virtual fence is 3 to 5 meters high, it can catch almost all mosquitoes that fly by.

The system is patented and the patent is specific about Anopheles:

For example, more than 99% of Anopheles mosquitoes (which may carry strains of malaria that can infect humans) fly at less than 3-5 meters of altitude

HYDE, Roderick A., et al. Photonic fence. U.S. Patent Application 14/255,119, 2014.


Malaria is a mosquito-borne disease that causes fever, chills, and flu-like illness if left untreated, it may even lead to death. The fight against malaria has been successful in the early 2000s, with 1.5 billion cases and 7.6 million deaths averted since 2000, but progress has been plateauing in the last five years. A report shows that in 2019, there were an estimated 229 million cases of malaria occurring worldwide and 409,000 deaths. One reason for this recent lack in progress is due to the rise in insecticide resistance in mosquitoes. Therefore, in order to curb malaria, new tools are needed to eradicate it, such as a technology called gene drive.

Briefly, gene drive is a genetic engineering technique that causes a particular gene to be passed on hereditarily at a higher than normal rate. For example, most genes have a 50% chance of being passed from parent to offspring based on the laws of heredity. However, a gene drive can disrupt this law —the gene can be transferred to more than 50% of the offspring, causing it to dominate the entire population. Therefore, synthetic gene drive can be used to spread an antimalarial trait throughout a mosquito population at a relatively fast pace, thereby eliminating malaria. However, there have been many problems with using this technology for malaria specifically many synthetic gene drives developed would either (1) modify an important part of the genome that leads to poor survivability of the organism, thus disrupting the population dynamics, or (2) affect a less important part of the genome that leads to poor preservation of the gene drive, reducing its ability to be passed onto offspring.

Recently, a group of scientists from Imperial College London developed an approach that targets the introns of the mosquito genome. Introns are a part of the DNA that do not later on get translated into proteins in other words, they are silent and do not affect the function of the DNA. Thus, this new synthetic gene drive is able to target an important part of the genome without worsening the survivability of the organism, thus solving the previous problem of affecting the population dynamics. Indeed, the researchers tested the gene drive in the African malaria mosquito A. gambiae and found that mosquitoes that carry the gene drive were able to pass on the genes to their offspring while remaining as healthy as mosquitoes that do not carry the gene drive. Therefore, their experiments provide preliminary yet promising evidence that their new approach of synthetic gene drives could work in mosquitoes. Hopefully, in the near future, synthetic gene drive can help us spread antimalarial properties to all mosquitoes that spread malaria, eliminating malaria once and for all.

The first author of the study, Astrid Hoermann, is a research associate in the Department of Life Sciences in Imperial College London, UK.


Genetically modified mosquitoes have been OK’d for a first U.S. test flight

The first U.S. tests of any free-flying genetically modified mosquito are now OK’d for 2021 to fight the dengue-spreading Aedes aegypti (shown).

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August 22, 2020 at 11:15 am

After a decade of fits and starts, officials in the Florida Keys have voted to allow the first test in the United States of free-flying, genetically modified mosquitoes as a way to fight the pests and the diseases they spread.

The decision came after about two hours of contentious testimony in a virtual public hearing on August 18. Many speakers railed against uncertainties in releasing genetically engineered organisms. In the end, though, worries about mosquito-borne diseases proved more compelling. On the day of the vote, dengue fever cases in Monroe County, where the Keys are located, totaled 47 so far in 2020, the first surge in almost a decade.

The same mosquitoes known for yellow fever (Aedes aegypti) also spread dengue as well as Zika and Chikungunya (SN: 6/2/15). The species is especially hard to control among about 45 kinds of mosquitoes that whine around the Keys. Even the powerhouse Florida Keys Mosquito Control District with six aircraft for spraying — Miami has zero — kills only an estimated 30 to 50 percent of the local yellow fever mosquito population with its best pesticide treatments, says district board chairman Phil Goodman.

“We can’t rely on chemistry to spray our way out of this,” Goodman, a chemist himself, said as the commissioners conferred after the public’s comments. Then 4–1, the commissioners voted to go forward with a test of genetically modified males as pest control devices.

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Sometime after January 1, 2021, Florida workers will set out boxes of eggs of specially bred male yellow fever mosquitoes (a recent version called OX5034) in a stretch of Monroe County still to be chosen. The eggs, shipped from the biotech company Oxitec based in Abingdon, England, will grow into normal-looking males. Like other male mosquitoes, they drink flower nectar, not blood.

Then planners hope that during tests, these Oxitec foreigners will charm female mosquitoes into mating. A bit of saboteur genetics from the males will kill any female offspring resulting from the mating, and over time that should shrink the swarms. Sons that inherit their dad’s no-daughter genes will go on to shrink the next generation even further.

By now, Oxitec has supplied some billion saboteur male mosquitoes for release elsewhere around the world, especially in Brazil, where Zika can flare up and dengue is common (SN: 7/15/16). The notion of releasing sterile males of a pest to romance the population down to some scattered lonely hearts is at least 80 years old (SN: 6/29/12). For decades, that meant sterilizing males by exposing them to radiation and then releasing them into the wild. But mosquitoes were too delicate for the radiation techniques of the time. When scientists figured out an efficient way to tweak a fruit fly’s natural DNA, reported in 1982, hopes rose for genetically sterilizing male pest insects.

In Oxitec’s method, some of the mosquito genes of the breeding stock not involved in the daughter-killing mechanism can spread a bit into any wild populations of the species, at least for a while. Yet researchers have argued that Ae. aegypti mosquitoes probably hitchhiked on ships into the Americas, so preserving their wild genetics in the United States would just mean coddling an invasive species. Also, introducing some gene that would make the U.S. wildlings more of a nuisance than they already are seems unlikely, says public health entomologist Kevin Gorman from Oxitec.

In spite of years of drama over the Keys’ consideration of releasing GM mosquitoes (SN: 5/8/17), Florida’s batch will not be the first GM insects to fly free in the United States. (And if it weren’t for COVID-19, they might not be the only mosquito pioneers the U.S. Environmental Protection Agency simultaneously approved an experimental release in Houston’s Harris County, now on hold during the pandemic.) The first GM insects released in the United States, also from Oxitec, were early versions of pink bollworm moths for an eradication program to wipe out this cotton pest in the U.S Southwest. That genetic tweak merely supplied a marker that would identify irradiated insects but didn’t change any fertility genes.

One prototype capsule can hold thousands of Oxitec’s genetically modified male mosquitoes. The company ships capsules from the United Kingdom to places like Brazil and, soon, Florida. Oxitec

The first GM insects with fertility tweaks (Oxitec again) were diamondback moths (SN: 7/14/17). “We would love to have been the second,” says entomologist Tony Shelton of Cornell University. Instead the first-of-its kind project sparked 673 individual comments, 78 percent of them not happy, when regulators posted the application to release the moths in 2017 in a New York field.

The new application to test GM mosquitoes in Florida, however, got 5,656 comments, plus a petition against the project that drew more than 25,000 signatures. Even though people probably detest mosquitoes more than moth larvae that can damage broccoli, the fact that the Florida Keys project involves genetic modification still stirs passion.

As far as specific concerns go, one common one involves antibiotics, says Oxitec’s Gorman. To keep females in the breeding stock alive, the company adds the antibiotic tetracycline to the water where the larvae dangle rump-up before transitioning to aerial adulthood. That suppresses the killing mechanism, which involves a protein that’s blocked by tetracycline. When people put eggs in the wild, there’s no antibiotic, so daughters die. The egg parents’ history with antibiotics has raised concerns that egg releases might encourage the spread of antibiotic-resistant bacteria.

Gorman contends that that’s not likely. The EPA has required testing sites at least 500 meters away from sewage plants (where antibiotics show up in waste and in theory might keep some daughters alive) and citrus orchards (which can get treated with antibiotics for their own diseases). Also, the latest version of these mosquitoes is shipped from the United Kingdom as cleaned male eggs. Their moms laid the eggs as adults living in air instead of in the youngsters’ tetracycline-tinged soup.

Some of the more general objections to the project may have more to do with suspicions of government and for-profit businesses than with mosquito biology. Some unease, too, may come just from basic human reactions to risk and control, says public health entomologist Natasha Agramonte, who has no connection with Oxitec but has been working with mosquitoes at the University of Florida in Gainesville. Car crashes injure several million Americans a year, but driving lets people feel they’re in control. Watching abundant mosquitoes being released, though? Not so much.

Questions or comments on this article? E-mail us at [email protected]

A version of this article appears in the September 12, 2020 issue of Science News.


Mosquito

A newspaper report covering Arnob Chakrovorty's bite on facts-based discussion supporting World Health Organisation's claim that the Coronavirus disease (COVID-19) caused by SARS-CoV-2 cannot be transmitted by the mosquitoes. Published in Sangbad Pratidin Newspaper (Bengali): issue date-1/Aug/2020, pp. 1&5.

Cite this article as: Chakrovorty, Arnob, and Goutam Brahma. “A Newspaper Report Discussing the Potential of the Mosquito to Transmit Coronavirus Disease (COVID-19).” Sangbad Pratidin, 1 Aug. 2020, pp. 1–5.

Fahim Amir’s “Cloudy Swords” encounters a colonial avant-garde of honeybees spreading with white settlers in America, mosquito armies that recall past colonial panic and present viral dilemmas, and insects determined to colonize the colonizer in the twentieth century.

"Cloudy Swords" ist excerpted from Fahim Amir, Being and Swine: The End of Nature (As We Knew It), trans. Geoffrey C. Howes and Corvin Russell (Between the Lines, 2020).

You won’t always have guests at home. Sometimes or even most of the time, you will have intruders in the form of pests. Have you often wondered how these pests make way and multiply without your knowledge? Here are some ways that you could have a pest as a guest in your home.
Through open doors and windows - The windows and doors are the most common inlets for the pests to enter your home.
Through chambers - Pests like rodents, roaches and even the millipedes are very good swimmers. They can enter your home through the drainage chambers.
Because of open garbage bins - Most of the pests are mainly scavengers and make your home theirs because of enough food and water supply. The unclean vessels in the kitchen along with open garbage bins are an open invitation for all of the pests to visit your place.

With all of these, the most common pests you would encounter at your home are the roaches, mosquitoes,rodents and spiders. It is very easy to keep them out with these simple hacks.

For the mosquitoes -
Make sure you do not have any stagnant water areas in your home. These are the breeding places of many mosquitoes.
Grow some catnip or lavender plants around your home.
Diffuse lavender oil using an oil diffuser to keep the mosquitoes away.
Use a good all natural pest control spray for mosquitoes at home.

For the rats -
Keep the garbage bins at home closed.
Use a good and safe rodent control spray that is made of peppermint oil. Rats hate the fragrance and run away.
Use a potato bait if glue traps do not work. Rats, on eating the dried and powdered skin of potato, have their intestines bloated and die.
Keep the chambers sealed as rats are very good swimmers.

For the roaches -
Do the dishes at night so that you do not have roaches breeding in your kitchen.
Use airtight storage containers to store food and groceries.
Roaches can live by eating paper. Clear all the stacked paper away.
Use pest repellent pouches for extra protection from a roach-attack.

For the spiders -
Break the cob webs down if you do not wish to have a halloween decor on your walls all through the year.
Use a good pest repellent spray that can repel spiders. Choose a stainless one so that your walls do not get stained.
Close all the cracks and holes in the walls and windows as these can be the place of spider infestation.
Keep the lights low as spiders come out during the dusk hours near bright lights to hunt down tiny insects that stay near the light.

These are the most simple tricks and tips to have a pest-free house. Try them to never see a pest around you again.


Mosquito physics - Biology

It is like when your cell phone keeps you awake in bed&mdashexcept mosquitoes do not doom scroll when they stay up, they feast on your blood.

Full Transcript

Emily Schwing: This is Scientific American&rsquos 60-Second Science. I&rsquom Emily Schwing.

Imagine this: you&rsquore in a lab in Indiana. Your arm is stuck in a box. The box is filled with bloodthirsty insects. And those insects? Well, they intend to feed on you.

Giles Duffield: The staff scientist who works with me, Dr. Samuel Rund, he has a very good arm that he doesn&rsquot mind exposing to mosquitoes to feed off him.

Schwing: Notre Dame Professor Giles Duffield convinced a colleague to play the role of blood meal for his research on mosquito genetics and behavior. It&rsquos published in the American Journal of Tropical Medicine and Hygiene. [Samuel S. C. Rund et al., Artificial light at night increases Aedes aegypti mosquito biting behavior with implications for arboviral disease transmission]

Duffield cared less about whether his colleague would be delicious&mdashthat was obvious. What he really wanted to know was&mdashlike humans kept awake by the light of their cell phones&mdashwould artificial lighting keep mosquitoes up and biting deep into the night?

So Duffield and his colleagues created an experiment: they&rsquod monitor the biting behaviors of mosquitoes who had been exposed to pulses of artificial light throughout the night.

Duffield: It doubled their biting activity, the feeding activity. And so, obviously, this could have big implications. So the effect on the biting at night was the levels of biting were approaching those that we would see during the late afternoon, when we expect to see that peak biting. So it&rsquos not a small change. It&rsquos a very robust increase in the biting behavior.

Schwing: There are a number of different species of mosquitoes, and they behave in different ways. Some bite only at night, others are daytime feeders. But there&rsquos one species in particular that Duffield and colleagues were focused on: Aedes aegypti.

Duffield: Aedes aegypti sort of evolved alongside humans and is very adept to living within human habitation. So any sort of environmental changes that would influence its feeding and biting behavior could have huge ramifications on humans, probably more than any other mosquito species.

Schwing: Duffield says Aedes aegypti are the major vector for the human transmission of diseases like encephalitis, chikungunya, malaria, dengue fever and the Zika virus: all diseases that have made headlines in recent years.

And that&rsquos why he needed his colleague&rsquos arm.

Duffield: We feel as though this is a nice, simple assay. And it represents a more natural stimulus for the mosquito: carbon dioxide, odorant smells, body temperature, the attraction to warmth, and the physical skin and the chemicals that are released from the skin. So it certainly represents a more natural host-mosquito-biting response. But yeah, it's unfortunate for those who are the investigators. When you get 30 mosquito bites per assay, it&rsquos painful sometimes.

Schwing: The next step is to look at how different species of mosquitoes respond to different kinds of light.

Duffield: Yeah, so that&rsquos something that we&rsquore busy trying to investigate right now: In the original experimentation, we just use broad-spectrum white light. And as we fine-tune current and future experiments, we&rsquore interested in seeing if specific wavelengths, or color, color spectrums of light, have the same effect or less effect.

Schwing: And Duffield has some ideas.

Duffield: So possibly the brighter the light, the larger the effect. But again, you may find extremely bright light inhibits the mosquito. So it may be a sort of sweet spot in the intensity of light, the illuminance.

Schwing: He says the color of light and the time of the night when mosquitoes are exposed to light are also parameters worth exploring. He&rsquos also interested in studying different species of bloodsucker. Not all mosquitoes feed at night. Since some are day feeders, it raises the question of whether artificial light at night would affect them at all.

Eventually, the goal is to figure out if they can make recommendations on how people in mosquito-prone parts of the world should light their homes.

In the short term, though, future findings will hopefully disarm hungry mosquitoes&mdashwhile preserving the arms of the study subjects they feed on.


Biology Professor Monitoring New Mosquito Borne Virus

CAPE GIRARDEAU, Mo., July 23, 2014 – Dr. Christina Frazier has dedicated her career to what goes buzz in the night, working to protect thousands of Missourians from those summertime pests — mosquitoes.

This summer began no differently than the past 35 years. She’s already tested 1,500 pools of 50 vector mosquitoes each from St. Louis County in Southeast Missouri State University’s Arbovirus Lab. Frazier tests the pools to determine if they include mosquitoes carrying West Nile Virus. About 12 of those pools have tested positive for West NileVirus, she said.

“That’s a little low,” said Frazier, professor of biology. “The virus is still active in St. Louis County. There’s no question” about that. “I don’t think we’ll have a bumper crop this year. We are getting good numbers in St. Louis, but they aren’t that huge.”

Her concern this summer, though, has turned to chikungunya, a virus transmitted by mosquitoes causing an epidemic in the Caribbean with cases now identified in Florida. The name “chikungunya” is derived from a native African dialect, where the disease was first identified, she said. “Chikungunya” means “to bend up,” Frazier says, because the disease causes extreme joint pain and fever.

One of the mosquitoes that transmits this virus is called Aedes albopictus, commonly known as the Asian Tiger mosquito.

“We have a lot of these in Cape Girardeau,” she said, adding they are prevalent in the St. Louis area as well.

The mosquitoes spread chikungunya by biting someone who has the virus, then biting other people.

Chikungunya, Frazier said, is rarely as deadly as West Nile Virus, but causes more pain. The virus has not been detected in this part of the country yet, but is cause for concern, she said.

To reduce the risk of being bitten by an Aedes albopictus mosquito, like other mosquitoes, people should rid their yards of objects that hold water, such as old tires, bird baths and dog water dishes, she said, as they become breeding grounds.

Beginning in 1994, Southeast Missouri State University became the site of a statewide mosquito testing lab under an agreement with the Missouri Department of Health to conduct mosquito surveillance. Under the partnership, county health departments from across Missouri sent trapped mosquitoes in weekly batches during summer months to Southeast’s Arbovirus Lab to determine if the pests were carrying either West Nile Virus or St. Louis Encephalitis.

After years of collaborative work, the Lab quit testing mosquitoes collected locally seven years ago and stopped training county health department officials to trap them two years ago when federal funding for the project came to a halt. But Frazier’s work with St. Louis County Vector Control to monitor mosquitoes from St. Louis County continued. The county uses the information gleaned from the Lab’s testing to concentrate their mosquito control efforts, she said.

St. Louis County Vector Control will step up its involvement when it takes over the work of the Arbovirus Lab Aug. 1 when Frazier plans to retire from Southeast Missouri State University. Frazier will begin training their staff on how to test for vector mosquitoes beginning this week.

“I’m happy St. Louis County is picking it up,” she said.

For Frazier, her life’s work has been a labor of love that was sparked as an 11 th grade student in upstate New York. That’s when her biology teacher introduced her to microbiology, and Frazier broke the news to her father, an electrical engineer, that she planned to pursue a career as a biologist, not an engineer. And, as the saying goes, the rest is history.

She enrolled as an undergraduate in the College of Agriculture at Cornell University, where she spent a summer working in the microbiology lab. After earning her undergraduate degree at Cornell, she was invited to work for a summer in Yale University’s Arbovirus Research Unit in the area of epidemiology, where she worked both in the laboratory and the field. Having spent a fair amount of time working on a family farm, she felt comfortable in the outdoor setting as well as in the laboratory, she said.

She returned the following year as a doctoral student at Yale, where she earned a doctoral degree in virology/epidemiology with an emphasis on arboviruses. She launched her career teaching freshmen chemistry at Quinnipiac College in Hamden, Conn. Her final year there was spent teaching microbiology before she joined Southeast Missouri State University where she’s taught and researched for 35 years in addition to serving as associate to the provost for data analysis and assessment.

“The nice thing about it was no one was doing arboviruses here,” she said, so she could build the Southeast Missouri Arbovirus Lab with grant funding from the ground up in Rhodes Hall of Science.

Next month, she plans to return to her native stomping grounds just west of Syracuse, N.Y. She says she will split her time between her family in New York and fellow graduate school classmates in St. Augustine, Fla. Frazier says she is considering volunteering her time with the mosquito control district on Anastasia Island, east of St. Augustine. This fall and next spring, she also will teach a biology webinars online at Southeast, covering immunology, pathogenic microbiology and epidemiology.

“I know I will stay in contact with St. Louis County until they are established,” she said, “and I will stay in contact with Anastasia,” eventually weaning away from teaching.

“I feel we’ve accomplished something,” here in Missouri, Frazier said. “I’m leaving the state in a much better position for Arbovirus surveillance than when I got here.”

During her tenure, she created a pictorial mosquito key distributed to Missouri county health departments to help them identify vector mosquitoes and trained some 25 students in the laboratory.

“The thing I’m proudest of is that two of them went on to get Centers for Disease Control Fellowships in epidemiology,” she said. “It’s the culture of our department that encourages, supports, challenges and hires people who do research involving students that’s really important.”

Her work at Southeast, she says, “allowed me to train students. We do what we do to provide opportunities to students. Southeast has provided a service (vector mosquito surveillance) to the region and the state, and allowed me to do what I love to do, both in the field and in the laboratory.”

Frazier says her work as a virologist at Southeast has proven to be the perfect mix of field work and laboratory research with a focus on her natural orientation toward virus transmission and public health.

“I think Missouri has shown that you could do a decentralized response” to mosquito surveillance with already established resources, she said. “We showed that using existing resources and with little money, you could mount an effective surveillance statewide program for arboviruses. They couldn’t have done it without the biosafety lab here at Southeast.”


5. Passive dissemination via road transport

Figure 7. Variation in environmental conditions between introduced populations in Europe and their source populations. Spaces represent the environmental range encountered in each region, determined from occurrence and environmental data (temperature, precipitation, anthropisation). The arrows link space centroids source to visualise environmental change. [Source: © Stéphanie Sherpa, modified from 20] The intracontinental dispersal of the tiger mosquito after introduction is mainly due to the passive transport of eggs via road transport, particularly used tires [21]. Indeed, numerous detections of tiger mosquitoes have been reported in tire storage areas. However, recent research has highlighted the role of daily car travel in the dispersal of adults [22].

There is a direct causal relationship between dispersal [23] and gene flow between populations. Therefore, landscape genetics [24] seeks to identify geographic and landscape factors that promote population connectivity. In contrast to colonisation routes, that are reconstructed at a global scale, population connectivity must be studied at a local scale. Although human-assisted long-distance dispersal can be characterized by “jumps”, expansion fronts provide excellent natural laboratories for studying landscape factors affecting population connectivity.

Figure 8. Changes in the geographical distribution of the tiger mosquito over time in the region of Grenoble, France. A: map showing the three valleys on either side of Grenoble and B: limits of distribution per year since introduction in 2012, showing only the expansion front (uninhabited areas within these expanses are not shown). [Source: © Stéphanie Sherpa] Among the areas recently invaded by the tiger mosquito, the Grenoble region, where it has been present since 2012, is an excellent study area for understanding the expansion dynamics of invasive species. Expansion has only been possible in three directions on either side of Grenoble, corresponding to the three valleys located between the Vercors, Chartreuse and Belledonne massifs (Figure 8).

Modelling the factors structuring the genetic variability of populations at the Grenoble landscape scale, using different types of habitats (open habitats, forests, dense urban areas, residential urban areas, rivers, road networks), revealed that passive dispersal of tiger mosquitoes along road axes induces strong connectivity between geographically distant populations on either side of Grenoble [25] (Figure 9).

The tiger mosquito has a low natural dispersal capacity of about 200m per generation on average based on estimations from capture-recapture rates [26]. The generation time [27] is about three weeks in the tiger mosquito. Environmental conditions in the Grenoble region being favourable for reproduction from May to October, the species can theoretically complete up to seven generations per year. Thus, the maximum natural dispersal of individuals between 2013 and 2017 is limited to a radius of 6 km. As the geographical distance between genetically close populations on either side of identified roads (Figure 9) can be up to 25 km, this study confirms that the main factor explaining the connectivity between distant populations in the tiger mosquito is human transport along roads.


Mosquitoes Can Hear Sound over Surprisingly Long Distances

Mosquitoes can hear up to 32 feet away. Image credit: Egor Kamelev.

Mosquitoes have been known to use a variety of senses to detect the presence of potential mates and food sources. They can see, smell and most importantly hear what is around them.

However, it was previously believed that their hearing capabilities would be limited.

“It’s been known for quite a long time that male mosquitoes are drawn to the sound of the female’s beating wings,” said Cornell University’s Professor Ron Hoy, senior author of the study.

“We noted that since mosquitoes mate in mid-air, the sound of the female’s wings buzzing sets the males in motion.”

“Previous experiments to prove that males are drawn to the sounds of females in flight were done at close range, which reinforced the idea that they only hear at close range — up to one foot (30 cm).”

Past studies by Professor Hoy and co-authors to prove hearing in jumping spiders gave them the methods and skills needed to tap the auditory nerves of mosquitoes, and record the electrical potential of the excited nerves.

Initial tests in the lab revealed that auditory nerves of Aedes aegypti mosquitoes picked up sounds from across a room.

To prove this principle, the researchers set up an experiment in a field house with a 100-foot (30 m) ceiling that would reduce echoes.

They fitted mosquitoes with an electrode in their brains and made neurophysiological recordings of the auditory nerve being stimulated by pure-tones emitted from a loudspeaker 32 feet away.

“They’re hearing at distances that normally require ear drums, but these are hairs,” Professor Hoy said.

“Ear drums work by picking up pressure from sound waves, while tiny hairs sense sound from air particles vibrating at certain frequencies.”

The team then moved the nerve physiology equipment to a super-quiet anechoic room.

“We found the sweet spot of frequency that the mosquitoes are sensitive to was between 150 to 500 Hz (hertz),” said study first author Dr. Gil Menda, a postdoctoral researcher at Cornell University.

The scientists played back the tones of females’ wings beating, which occurs at a frequency of about 400 Hz.

In behavioral experiments, when these 400-Hz tones were played from as far as 10 feet (3 m) away, male mosquitoes in a mesh cage all instantly took to flight. The behavioral reaction was proved in individuals, to make sure they weren’t taking flight as part of a group response.

The mosquitoes’ frequency range for hearing also overlapped with human speech.

“The most energetic frequencies of an average human vowel is in the range of 150 to 900 Hz, so they should be able to hear people speaking,” Professor Hoy said.

“Also, using the anechoic room, we showed the sensitivity of the male mosquito was so low that when we played a tone, it was hard for us to hear it, but we can see the mosquito can hear it,” Dr. Menda said.

The study authors recorded excited auditory nerves at 30 dB (decibels). Human speech is typically spoken at 45 to 70 dB, also within the mosquito’s sweet spot.

“We were able to observe the behavior of male mosquitoes to recorded sounds of either male or female mosquitoes,” said study co-author Professor Ron Miles, of Binghamton University.

“When the sounds from male mosquitoes were played, the males mostly just sat there. But, when we played the sounds of females, the males took off flying.”

“We were also able to measure the neural response of their antennae and found they can hear sounds from surprisingly far away in the same frequencies that are important for human speech.”

“While our study provides both neurophysiological and behavioral evidence that male mosquitoes hear sounds from far field, it offers no proof that they use it to home in on people. The insects are known to pick up sensory cues such as carbon dioxide, odors and warmth to locate people. But the results do show an intriguing correlation,” Professor Hoy said.


Graphene fabric keeps mosquitoes from biting

The mosquito Aedes aegypti (seen on human skin) transmits several dangerous diseases, including Zika. Researchers have shown that these bloodsuckers can’t bite through a fabric made of graphene.

TacioPhilip/iStock/Getty Images Plus

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October 30, 2019 at 5:45 am

Mosquito bites aren’t just a nuisance on summer hikes or backyard patios. For millions of people around the world, they can bring deadly diseases. Now, researchers have proposed a new strategy to keep our skin bite-free. Add a layer of graphene to your outerwear.

Graphene is a single layer of carbon atoms. Identified in 2004, graphene earned its two discoverers the 2010 Nobel Prize in physics. Millions of graphene layers form the graphite in school pencils. Attaching oxygen atoms to graphene produces a film known as graphene oxide (GO). And that’s the basis of the new fabric.

Cintia Castilho is a graduate student in engineering at Brown University. That’s in Providence, R.I. She was intrigued when Robert Hurt, her advisor, mentioned mosquito protection at a team meeting. “Our group had used GO in clothing that protects against chemical vapors,” Castilho recalled. “From that and other applications, we knew it’s an extremely versatile material.” Yet, could it keep a mosquito from biting?

This project showed Castilho that any idea may be worth trying, even when some of your colleagues are skeptical. Her team described its success in the September 10 Proceedings of the National Academy of Sciences.

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The mosquito’s unique toolkit

Castilho learned that a mosquito’s mouth consists of more than a straw to slurp up blood. In fact, there are six mouthparts. They are, in some ways, like dinnerware. “A mosquito holds your skin with two mouthparts that act as a fork,” she explains. Another four parts have knife-like serrated edges. They cut into your skin.

Only a female needs a blood meal. It will nourish her eggs. The mouthparts of males can’t penetrate skin. Some biting flies have mouthparts similar to those of a female mosquito. But none are as unique and powerful as hers.

Scientists Say: Graphene

Some female mosquitoes strongly prefer human blood. A prime example is Aedes aegypti, which transmits many dangerous diseases. They include Zika, dengue (DEN-gay) fever, yellow fever and chikungunya (Chih-kun-GUN-yah).

“We think that Aedes aegypti comes from Africa and reached other continents with our ancestors,” says Laura Harrington. People likely transported it in human-made water containers, she says. “It’s basically a domesticated animal that can’t survive without people.”

Harrington is an insect scientist, or entomologist, who wasn’t involved in the new project. She works at Cornell University in Ithaca, N.Y. The mosquito A. aegypti can feed on many mammals, she’s found. But it prefers people 98 percent of the time. During millions of years of evolution, 3,500 mosquito species have developed different body adaptations and behaviors. These help them feed on whatever animal they prefer.

Explainer: What’s a virus?

Female mosquitoes transmit diseases through a channel formed by their mouthparts. They inject their saliva (spit) before pumping the host’s blood out. The mosquito’s saliva contains molecules that stimulate blood flow and prevent clotting. But sometimes that spit carries viruses from a blood source on which the insect previously fed.

We try to prevent mosquito-borne disease with protective clothing, chemical repellents, bed nets — even some drugs. But those drugs are too expensive for most people in poor countries. The same is true for vaccines. They are difficult and costly to develop. And for many diseases, they don’t even exist.

Harrington is excited about the new study because graphene-based materials are a new idea. “We’re losing the battle against infectious diseases,” she says. “Any promising new technology for mosquito protection is something we should pursue.”

Graphene oxide vs. mosquito

To test graphene oxide’s prowess, Castilho’s group needed human recruits willing to expose their arms to mosquitoes. The researchers covered a volunteer’s skin with cheesecloth, a light, airy fabric. Then they let 100 mosquitoes loose on the volunteer for five minutes. (The researchers made sure those mosquitoes were free of dangerous viruses.) A volunteer would end up with about 10 bites per square inch of exposed skin.

Then the researchers ran the test again. This time they used some cheesecloth to hold the GO film in place. After another five minutes with the insects, the volunteer would have no mosquito bites.

The researchers thought the film would be a mechanical barrier — like a wall. In that case, mosquitoes should still land on the arm. In fact, almost no mosquitoes landed on a GO-protected arm.

To better understand why, the researchers added water to the film. That simulates human sweat, which is known to attract mosquitoes. And now mosquitoes did land on the arm. They also were able to bite. So while dry GO was fully protective, wet GO was not. (Mosquito bites were still less frequent with wet GO than with cheesecloth alone.)

A microscope showed what happened. Wet GO has a mushy structure that makes it a less effective shield. To restore its original protection, the researchers changed GO’s chemistry. They applied a vapor to the film. That removed most of the oxygen molecules. It was now what chemists call reduced graphene oxide (rGO). Wet rGO doesn’t get mushy. And the wet rGO film kept mosquitoes from biting, even when they landed.

These results showed that wet rGO was the mechanical barrier the researchers had expected to find. Dry GO, on the other hand, blocks some (smelly) chemicals that our skin emits with sweat. These chemicals help mosquitoes find nearby people to bite. Other attractants include heat, humidity, carbon dioxide and visual cues.

Castilho is confident that rGO will work for other kinds of mosquitoes, too. The size of the mouthparts and the sensing system are very similar in all species.

Two kinds of barriers to explore

Matthew Daly is a materials engineer who studies graphene at the University of Illinois at Chicago. He was not involved in the project but is impressed by its findings. “The science is excellent,” Daly says. “And the use of graphene for mosquito control is new and timely.”

Explainer: The bacteria behind your B.O.

The Brown University researchers know that rGO is not a breathable material. That’s why they plan to test if other chemical changes can keep GO fully protective in moist conditions. Daly notes that one of the challenges will be finding the right chemistry. The ideal material needs to stick together while remaining breathable.

Rakesh Joshi is also impressed with the work, especially the potential of rGO. He is a materials scientist at the University of New South Wales. That’s in Sydney, Australia. “I think it’s possible to make composite fabrics with an rGO coating,” Joshi says. Composite materials contain two or more components with different properties.

Joshi thinks teaming up with textile companies would be a great next step. More research might show which graphene-based material is the best barrier. The company could help get it into clothing that’s comfortable to wear and easy to clean.

The goal is durable and affordable clothing that deters mosquitoes and protects against diseases. Future studies of the technology also may lead to products that work directly on the skin.

This is one in a series presenting news on technology and innovation, made possible with generous support from the Lemelson Foundation.

Power Words

adaptation (in biology) A process by which an organism or species becomes better suited to its environment. When a community of organisms does this over time, scientists refer to the change as evolution.

Aedes aegypti A species of mosquito that can transmit the viruses responsible for several tropical diseases, including dengue fever, yellow fever and West Nile disease.

application A particular use or function of something.

atom The basic unit of a chemical element. Atoms are made up of a dense nucleus that contains positively charged protons and uncharged neutrons. The nucleus is orbited by a cloud of negatively charged electrons.

attractant A chemical that lures an organism, usually by odor.

behavior The way something, often a person or other organism, acts towards others, or conducts itself.

bug The slang term for an insect. Sometimes it’s even used to refer to a germ.

carbon dioxide (or CO2) A colorless, odorless gas produced by all animals when the oxygen they inhale reacts with the carbon-rich foods that they’ve eaten.

chemical A substance formed from two or more atoms that unite (bond) in a fixed proportion and structure. For example, water is a chemical made when two hydrogen atoms bond to one oxygen atom. Its chemical formula is H2O. Chemical also can be an adjective to describe properties of materials that are the result of various reactions between different compounds.

chemistry The field of science that deals with the composition, structure and properties of substances and how they interact. Scientists use this knowledge to study unfamiliar substances, to reproduce large quantities of useful substances or to design and create new and useful substances. (about compounds) Chemistry also is used as a term to refer to the recipe of a compound, the way it’s produced or some of its properties. People who work in this field are known as chemists.

chikungunya A tropical disease that has been crippling large numbers of people in Africa and Asia. It’s caused by a virus that is spread by mosquitoes. It recently has been spreading widely throughout warm nations. More than 3 million people have suffered through its initial flu-like symptoms. A large share may also go on to develop intense pain in their muscles and joints that can last months to years. There is no cure or vaccine.

colleague Someone who works with another a co-worker or team member.

component Something that is part of something else (such as pieces that go on an electronic circuit board or ingredients that go into a cookie recipe).

composite A material made using two or more different building blocks, which together produce something with new and better features. Carbon fiber reinforced polymers are one example. Embedded in these hard and strong plastics are tiny fibers made from carbon. Engineers use these plastics to build lightweight bodies for race cars and airplanes, among other things.

continent (in geology) The huge land masses that sit upon tectonic plates. In modern times, there are six established geologic continents: North America, South America, Eurasia, Africa, Australia and Antarctica. In 2017, scientists also made the case for yet another: Zealandia.

dengue A potentially lethal infectious disease transmitted by mosquitoes. No vaccine yet exists to prevent infection with the virus responsible for the disease, which causes high fevers, severe headache, joint pain, pain behind the eyes, rash, bone pain and sometimes mild bleeding. A more severe form of the disease, known as dengue hemorrhagic fever can cause uncontrolled bleeding if not treated right away.

deter An event, action or material that keeps something from happening. For instance, a visible pothole in the road will deter a driver from steering his car over it.

develop To emerge or come into being, either naturally or through human intervention, such as by manufacturing. (in biology) To grow as an organism from conception through adulthood, often undergoing changes in chemistry, size and sometimes even shape.

domesticate (n. domestication) To turn a wild plant or animal species into a tame version, which can take many generations. A domesticated animal is one that has been bred in captivity for food or as a pet. A domesticated plant is one usually farmed or used for landscaping.

edge (n network mathematics) A connection or link between two people or things.

engineer A person who uses science to solve problems. As a verb, to engineer means to design a device, material or process that will solve some problem or unmet need.

entomologist A biologist who specializes in the study of insects. A paleoentomologist studies ancient insects, mainly through their fossils.

graduate student Someone working toward an advanced degree by taking classes and performing research. This work is done after the student has already graduated from college (usually with a four-year degree).

graphene A superthin, superstrong material made from a single-atom-thick layer of carbon atoms that are linked together.

graphite Like diamond, graphite (the substance found in pencil lead) is a form of pure carbon. Unlike diamond, graphite is very soft. The main difference between these two forms of carbon is the number and type of chemical bonds between carbon atoms in each substance.

host (in biology and medicine) The organism (or environment) in which some other thing resides. Humans may be a temporary host for food-poisoning germs or other infective agents.

humidity A measure of the amount of water vapor in the atmosphere. (Air with a lot of water vapor in it is known as humid.)

infectious An adjective that describes a type of germ that can be transmitted to people, animals or other living things.

insect A type of arthropod that as an adult will have six segmented legs and three body parts: a head, thorax and abdomen. There are hundreds of thousands of insects, which include bees, beetles, flies and moths.

malaria A disease caused by a parasite that invades the red blood cells. The parasite is transmitted by mosquitoes, largely in tropical and subtropical regions.

mammal A warm-blooded animal distinguished by the possession of hair or fur, the secretion of milk by females for feeding their young, and (typically) the bearing of live young.

materials scientist Someone who studies how the atomic and molecular structure of a material is related to its overall properties. Materials scientists can design new materials or analyze existing ones. Their analyses of a material’s overall properties (such as density, strength and melting point) can help engineers and other researchers select materials that are best suited to a new application.

microscope An instrument used to view objects, like bacteria, or the single cells of plants or animals, that are too small to be visible to the unaided eye.

molecule An electrically neutral group of atoms that represents the smallest possible amount of a chemical compound. Molecules can be made of single types of atoms or of different types. For example, the oxygen in the air is made of two oxygen atoms (O2) water is made of two hydrogen atoms and one oxygen atom (H2O).

Nobel prize A prestigious award named after Alfred Nobel. Best known as the inventor of dynamite, Nobel was a wealthy man when he died on December 10, 1896. In his will, Nobel left much of his fortune to create prizes to those who have done their best for humanity in the fields of physics, chemistry, physiology or medicine, literature and peace. Winners receive a medal and large cash award.

oxide A compound made by combining one or more elements with oxygen. Rust is an oxide so is water.

oxygen A gas that makes up about 21 percent of Earth's atmosphere. All animals and many microorganisms need oxygen to fuel their growth (and metabolism).

physics The scientific study of the nature and properties of matter and energy. Classical physics is an explanation of the nature and properties of matter and energy that relies on descriptions such as Newton’s laws of motion. Quantum physics, a field of study that emerged later, is a more accurate way of explaining the motions and behavior of matter. A scientist who works in such areas is known as a physicist.

Proceedings of the National Academy of Sciences A prestigious journal publishing original scientific research, begun in 1914. The journal's content spans the biological, physical, and social sciences. Each of the more than 3,000 papers it publishes each year, now, are not only peer reviewed but also approved by a member of the U.S. National Academy of Sciences.

reduced (in chemistry) An adjective that describes something that has undergone a process (reduction) in which an atom gains an electron by stealing it from another atom or molecule. Reduction is the opposite of oxidation.

serrated A description for a saw-like edge, usually found on knives meant to cut through tough meat.

simulate To deceive in some way by imitating the form or function of something. A simulated dietary fat, for instance, may deceive the mouth that it has tasted a real fat because it has the same feel on the tongue — without having any calories.

skeptical Not easily convinced having doubts or reservations.

species A group of similar organisms capable of producing offspring that can survive and reproduce.

strategy A thoughtful and clever plan for achieving some difficult or challenging goal.

technology The application of scientific knowledge for practical purposes, especially in industry — or the devices, processes and systems that result from those efforts.

textile Cloth or fabric that can be woven of nonwoven (such as when fibers are pressed and bonded together).

trait A characteristic feature of something. (in genetics) A quality or characteristic that can be inherited.

transmit (n. transmission) To send or pass along.

unique Something that is unlike anything else the only one of its kind.

vaccine (v. vaccinate) A biological mixture that resembles a disease-causing agent. It is given to help the body create immunity to a particular disease. The injections used to administer most vaccines are known as vaccinations.

vapors Fumes released when a liquid transforms to a gas, usually as a result of heating.

yellow fever A disease that creates flu-like symptoms that can start with fever, chills, headache, backache and vomiting. Roughly 15 percent of patients may go on to develop more serious disease. This can lead to uncontrolled bleeding, the failure of multiple internal organs — and death.

Zika A viral disease that can be transmitted to humans via mosquitoes. About 20 percent of infected people get sick. Symptoms include a slight fever, rash and pinkeye and usually fade quickly. A growing body of evidence suggests that the virus could also cause a devastating birth defect — microcephaly. Evidence suggests it may also cause neurological conditions such as Guillain-Barré syndrome.

Citations

Journal: C.J. Castilho et al. Mosquito bite prevention through graphene barrier layers. Proceedings of the National Academy of Sciences. Vol. 116, September 10, 2019, p. 18304. doi: 10.1073/pnas.1906612116.

About Silke Schmidt

Silke Schmidt is a freelance science writer with degrees in biostatistics and journalism. She enjoys covering the environment, engineering and medicine. She has two kids and two places she calls home, Wisconsin and Germany.

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How to get rid of Mosquitoes at Home?

Sometimes mosquitoes have a bad habit of bothering people in every possible way. As a means of protection against mosquitoes, people have developed many tools, among which special mosquito nets will be very useful, preventing mosquitoes from entering the house through open windows.

Another effective mosquito repellent can be odor-producing substances that repel mosquitoes. Although their disadvantage may be that the smell of repellents can have a bad effect not only on mosquitoes but also on people.


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