New genome sequence to provide insight into tiger mosquito and how deadly diseases are transmitted to humans

Pathogens and Global Health journal has just published details of the first draft genome sequence of Aedes albopictus, commonly known as the tiger mosquito and responsible for transmitting several deadly diseases to humans, such as dengue and chikungunya, potentially offering hope to millions around the world.

"This sequencing… offers great hope to our understanding of the mosquito and our ability to control it, potentially saving millions of lives in many areas of the world," -- Professor Andrea Crisanti, Editor-in-Chief of Pathogens and Global Health.

Big data battles small insect: Terabytes of mosquito pictures help enhance mosquito netting

Researchers at the University of Warwick's School of Engineering are using imaging technologies, that are normally applied to automotive engines and sprays, to image thousands of mosquitoes to help develop better netting and physical protection against the malaria spreading insect.

The University of Warwick engineers, David Towers, Natalia Angarita and Catherine Towers, are helping entomologist colleagues at the Liverpool School of Tropical Medicine, Philip McCall and Josie Parker, explore the best insecticide treatment and physical design of the protection for sleeping people in areas where mosquitoes are a problem.

In observing how mosquitoes engage with insecticide treated barriers such as netting, researchers have in the past mainly relied on recording just the final landing location, which does not give a full picture of how they approach and handle the protective barriers.

Mating with the wrong insect may cut yellow fever mosquito populations

Asian tiger mosquitoes can drive down yellow fever mosquito populations when the female chooses the wrong male with which to mate, UF/IFAS scientists say. Both insects transmit chikungunya and dengue, dangerous diseases affecting millions of people worldwide.

In a study published this month in the journal Infection, Genetics and Evolution, Post-doctoral Researcher Irka Bargielowski led a team of scientists that conducted field studies in Houston, Texas; Caracas, Venezuela; Franceville, Gabon and Singapore, Malaysia.

They studied mating between the Asian tiger and yellow fever mosquitoes and found that it in the wild, avoidance mechanisms evolved in yellow fever mosquitoes, Bargielowski said. That finding may help scientists predict population changes of the two mosquito populations.

Mosquito-repelling chemicals identified in traditional sweetgrass

BOSTON, Aug. 17, 2015 --Native North Americans have long adorned themselves and their homes with fragrant sweetgrass (Hierochloe odorata), a native plant used in traditional medicine, to repel biting insects, and mosquitoes in particular. Now, researchers report that they have identified the compounds in sweetgrass that keep these bugs at bay.

The team will describe their approach in one of more than 9,000 presentations at the 250th National Meeting & Exposition of the American Chemical Society (ACS), the world's largest scientific society, taking place here through Thursday.

Mosquitoes and other insects remain a pesky part of everyday life in many parts of the world, and their bites are linked to a range of serious diseases, such as malaria. To add to the arsenal of insect repellents, Charles Cantrell, Ph.D., investigates the components of plants used in traditional therapies. "We found that in our search for new insect repellents, folk remedies have provided good leads."

Sweetgrass is a meadow grass that is a native to northern climates, Cantrell says. "It gives off a sweet aroma that repels mosquitoes."

Fighting mosquito resistance to insecticides

Controlling mosquitoes that carry human diseases is a global health challenge as their ability to resist insecticides now threatens efforts to prevent epidemics. Scientists from the CNRS, IRD, Université Claude Bernard Lyon 1, Université Joseph Fourier in Grenoble and Institut Pasteur in French Guiana have identified new genetic markers for mosquito resistance to insecticides, which could improve its detection in the field. This work was published in Genome Research on 23 July 2015.

The ability of mosquitoes to resist insecticides represents a serious threat to the prevention of diseases such as malaria, dengue and Chikungunya. The detection and monitoring of the resistances developed by natural mosquito populations will be essential to enabling their management in the field for as long as there are no alternatives to the use of insecticides.

Repeat infection with malaria parasites might make mosquitoes more dangerous

In malaria-endemic regions, humans are often infected repeatedly with the Plasmodium parasite, and the consequences of such multiple infections are under intense study. In contrast, little is known about possible co-infection and its consequences in the Anopheles mosquitoes that transmit the disease. A study published on July 16th in PLOS Pathogens reports that not only can individual mosquitoes accumulate infections from multiple blood feeds, but also that an existing malaria infection makes mosquitoes more susceptible to a second infection, and that infections reach higher densities when another strain is already present.

Interested in interactions between malaria parasites and their insect hosts, Laura Pollitt, from the University of Edinburgh, UK, and colleagues in the US, asked whether and how mosquitoes can be infected with different Plasmodium strains, how such heterogeneous parasites interact in the insects, and whether such interactions affect transmission of malaria to vertebrate hosts.

The researchers set up cages of female Anopheles mosquitoes and allowed them at defined times to feed on mice infected with two different Plasmodium strains. This study design allowed them to examine how the presence of a co-infecting strain affects parasites that enter the vector first and second, and to test whether co-infection impacts mosquito survival.

The mosquito smells, before it sees, a bloody feast

The itchy marks left by the punctured bite of a mosquito are more than pesky, unwelcomed mementos of a day at the lake.

These aggravating bites can also be conduits for hitchhiking pathogens to worm their way into our bodies. Mosquitoes spread malaria, dengue, yellow fever and West Nile virus, among others. As the bloodsucking insects evolve to resist our best pesticides, mosquito control may shift more to understanding how the mosquitoes find a tasty -- and unsuspecting -- human host.

A team of biologists from the University of Washington and the California Institute of Technology has cracked the cues mosquitoes use to find us. As they report in a paper published July 16 in Current Biology, the minute insects employ a razor-sharp sense of smell to tip them off that a warm-blooded meal is nearby, and then use vision and other senses to home in on the feast.

"Very little was known about what a host looks like to the mosquito and how a mosquito decides where to land and begin to feed," said UW biologist Jeff Riffell, co-author on the paper and one of three professors collaborating on these efforts.

Virus-carrying mosquitoes are more widespread than ever, and spreading

Scientists behind the first global distribution maps of two species of dengue and chikungunya-carrying mosquitoes warn they are spreading to new areas where they could cause disease.

The population of the tiger mosquito, which is known to carry dengue and chikungunya, has rapidly expanded in parts of the US, Southern Europe and China over the past 10-15 years. A new study by scientists at Oxford University reports the growth and identifies areas not yet populated by the insects that are suitable for their survival, for example in Europe. The findings are published in the journal eLife.

"Given the lack of a vaccine or any antiviral treatment for either virus and the debilitating pain they both cause, knowing where the mosquitoes are spreading to and where they might turn up next is crucial for helping to protect communities," says first author Moritz Kraemer. This is especially true in Africa, where records are sparse.

Vaccine to protect global communities from malaria under development

A University of Oklahoma professor studying malaria mosquito interaction has discovered a new mosquito protein for the development of a new vaccine that is expected to stop the spread of the disease in areas where it is considered endemic. Malaria is transmitted by mosquitoes, and it infects millions of people in Africa, Asia and South America every year, causing a global health crisis. In addition to the local populations, U.S. military personnel stationed in these areas and travelers to these malaria-prone areas are at risk of becoming infected.

Jun Li, assistant professor in the Department of Chemistry and Biochemistry, OU College of Arts of Sciences, will travel to Kenya this July to test the newly-developed vaccine in the field. Since mosquitoes are essential for malaria transmission, Li and his colleagues from the OU Norman campus, the OU Health Sciences Center and John Hopkins University have found that an antibody used against a key mosquito protein inhibited malaria parasite invasion in mosquitoes. The antibody blocks the malaria parasite from the protein, which is needed for the parasite to invade mosquitoes.

Artificial blood to assist in mosquito control research

A "nuisance" is probably one of the nicest things people call mosquitoes.

Mosquitoes have been called the deadliest animal on the planet, because of the diseases they spread. So why would researchers want to develop an artificial buffet for them? The answer is simple. That "buffet" may lead to fewer mosquitoes. Stephen Dobson, a University of Kentucky professor of medical and veterinary entomology, believes his mosquito food can do just that. Others believe there's promise too.

Dobson's research on developing artificial blood for mosquitoes has made him a Grand Challenges Explorations winner, in an initiative funded by the Bill & Melinda Gates Foundation.

The artificial blood he developed will allow people in remote areas around the world to sustain colonies of mosquitoes, even in those areas with limited resources and difficult logistics.

Tracking genetic arms race between humans, mosquitoes

Every time you put on bug spray this summer, you're launching a strike in the ongoing war between humans and mosquitoes -- one that is rapidly driving the evolution of the pests.

Scientists studying mosquitoes in various types of environments in the United States and in Russia found that between 5 and 20 percent of a mosquito population's genome is subject to evolutionary pressures at any given time -- creating a strong signature of local adaptation to environment and humans.
This means that individual populations are likely to have evolved resistance to whatever local selection pressures are typical in their area -- and that understanding the genomes of those populations could one day help inform agencies about which pesticides are likely to be most effective against them.
"Mosquitoes adapt to heat, lifestyle, pesticides and so on -- and we see traces of that in their genome," said Sergey Nuzhdin, USC Dornsife College of Letters, arts and sciences professor and corresponding author of the study, which was published by Proceedings of the Royal Society B on June 17.

Protein discovery fuels redesign of mosquito-based malaria vaccine

A promising type of vaccine designed to eradicate malaria by blocking parasite transmission could be a step closer, as a result of experts uncovering new information about the targeted protein.

The international team of researchers co-led by Dr Natalie Borg from the Department of Biochemistry and Molecular Biology at Monash University, and Dr Rhoel Dinglasan from the Malaria Research Institute at the Johns Hopkins Bloomberg School of Public Health in Baltimore, USA, focused on a protein in the Anopheles mosquito midgut called AnAPN1.
The research, published in the journal Nature Structural & Molecular Biology, provides for the first time, detailed information on the shape of AnAPN1 and where antibodies against AnAPN1 that can and can't block parasite development, bind to the protein.

Mosquito sex-determining gene could help fight dengue fever

Males aren't relevant -- at least when it comes to disease transmission by mosquitoes.

Researchers with the Fralin Life Science Institute at Virginia Tech have identified a gene responsible for sex determination in mosquitoes that can transmit yellow fever, dengue, and chikungunya viruses.

Only female mosquitoes bite because they need blood for developing eggs, and researchers believe that a higher ratio of males could reduce disease transmission.
In a study published in the Science Express, the scientists identify a male-determining genetic switch called Nix in Aedes aegypti mosquitoes that underlies the difference between males and females.
These master switches often reside in genomic black holes, which is why none had been found in mosquitoes or other insects before.

Genes make some people mosquito targets, twins pilot study shows

The likelihood of being bitten by mosquitoes could be down to our genes, according to a study carried out on twins.

Although this was a pilot study, it provides exciting information which may allow us to understand more about how our intimate relationship with mosquitoes has evolved. Ultimately the finding could result in the development of better ways to control mosquitoes and the diseases they transmit.

Research from the London School of Hygiene & Tropical Medicine found, for the first time, an underlying genetic component to how attractive we are to mosquitoes and this is likely to be caused by genetic control of our body odour.

The findings are published in PLOS ONE and build on previous research where it was shown that attractiveness to insects is based on differences in body odour. People who are less attractive to mosquitoes produce natural repellents. It seems that this trait is genetically controlled.

Hormone receptor found that allows mosquitoes to reproduce

University of Georgia entomologists have unlocked one of the hormonal mechanisms that allow mosquitoes to produce eggs.

The results provide insight into how reproduction is regulated in female mosquitoes, which transmit agents that cause malaria and other diseases in humans and domestic animals. Their work was published in the April edition of the Proceedings of the National Academy of Sciences.

Mosquitoes feed on sugar water in Mark Brown's endocrinology lab at the University of Georgia.

Credit: April Sorrow/University of Georgia

The model for this research is the yellow fever mosquito, Aedes aegypti. Females have to consume a blood meal before they are able to produce a batch of eggs. The blood meal triggers the mosquito's brain to release two hormones, an insulin-like peptide known as ILP and an ovary ecdysteroid-ogenic hormone known as OEH, which activate processes in the female mosquito that result in mature eggs.

Asian rock pool mosquitoes on the move: Modeling identifies risk hotspots in Germany

Scientists at the Senckenberg Research Center for Biodiversity and Climate and at the Goethe University, in conjunction with other German colleagues, have developed distribution models for the invasive Asian rock pool mosquito. This mosquito species is a potential carrier of vectors for infectious diseases, such as dengue fever or West Nile virus. In a recent study, published in the scientific journal Parasitology Research, the scientists identified new risk hotspots in Southern Hesse, the Saarland and northern North Rhine-Westphalia, and they recommend a careful monitoring of this invasive insect.

 

 

 

Head of a female Asian rock pool mosquito.

Credit: © Senckenberg 

 

 

 Chinese mitten crabs, ring-necked parakeets, rheas and Egyptian geese: exotic species have long since become part of German ecosystems and now live right in our midst. In Germany alone, more than one thousand non-native animal species are registered -- but most of the introduced species do not survive the winter in our latitudes. "However, the Asian rock pool mosquito is a different case," says Professor Dr. Sven Klimpel, a parasitologist at the Senckenberg Research Center for Biodiversity and Climate and the Goethe University in Frankfurt, and he adds, "These mosquitoes have spread extensively across Germany and Europe in recent years." For the first time, the dipterans were reported in 2008 from southern Baden-Wuerttemberg; since then, populations have also become established in Lower Saxony, Rhineland-Palatinate and North Rhine-Westphalia. Contrary to the Asian tiger mosquito, the Asian rock pool mosquito is adapted to cooler temperatures and is perfectly able to cope with the climatic conditions in Central Europe.

Larval competition between invasive mosquitoes impacts their adult survival

With spring showers come Floridians' least-favorite companion -- the mosquito -- and a team of researchers with the University of Florida's Institute of Food and Agricultural Sciences has found in a recent study that larval competition between the Yellow Fever Mosquito and Asian Tiger Mosquito impacts adult survival, which may influence their ability to transmit dangerous diseases.

"We think of mosquitoes as winged pests. However, we also know that these winged pests are not only a nuisance, they can also transmit very nasty pathogens that cause disease in humans and animals," said Barry Alto, an assistant professor at UF's Florida Medical Entomology Laboratory, who led the study published this month in the Journal of Medical Entomology. "Older mosquitoes are potentially more dangerous because they have had a greater chance of becoming infected with pathogens, like dengue or chikungunya viruses, and so may transmit that pathogen to people."

Researchers master gene editing technique in mosquito that transmits deadly diseases

Traditionally, to understand how a gene functions, a scientist would breed an organism that lacks that gene -- "knocking it out" -- then ask how the organism has changed. Are its senses affected? Its behavior? Can it even survive? Thanks to the recent advance of gene editing technology, this gold standard genetic experiment has become much more accessible in a wide variety of organisms. Now, researchers at Rockefeller University have harnessed a technique known as CRISPR-Cas9 editing in an important and understudied species: the mosquito, Aedes aegypti, which infects hundreds of millions of people annually with the deadly diseases chikungunya, yellow fever, and dengue fever.

 

Image : Mosquito larvae from two different lines fluoresce in different colors thanks to genetic tags that were inserted using the CRISPR-Cas9 gene editing system.

Researchers led by postdoctoral fellow Benjamin J. Matthews adapted the CRISPR-Cas9 system to Ae. aegypti and were able to efficiently generate targeted mutations and insertions in a number of genes. The immediate goal of this project, says Matthews, is to learn more about how different genes help the species operate so efficiently as a disease vector, and create new ways to control it. "To understand how the female mosquito actually transmits disease," says Matthews, "you have to learn how she finds humans to bite, and how she chooses a source of water to lay her eggs. Once you have that information, techniques for intervention will come."

Malaria: A vector infecting both apes and humans

In 2010, a study revealed that the main agent of malaria in humans, called Plasmodium falciparum, arose from the gorilla. Today, the vector which transmitted the parasite from apes to humans has just been identified. A Franco-Gabonese research consortium has determined which species of anopheles mosquitoes transfer the disease to apes. Among them is Anopheles moucheti, known for biting humans. Therefore, it appears to be the species which originally infected us through our cousins. And it could do it again today.
The same vector.
IRD and CNRS researchers, in addition to their Gabonese partners based in the CIRMF in Franceville, wanted to determine the identity of the mosquitoes which transmit malaria to apes. To this end, they caught a thousand mosquitoes of the Anopheles genus, in close proximity to groups of wild or semi-wild primates. They then conducted analyses on the insects collected, belonging to fifteen different species, in order to detect which ones were infected by the Plasmodium malaria parasites. Two species of mosquitoes were thus revealed to be contaminated by these pathogenic agents. Anopheles moucheti was one of them -- a major vector for humans in Central Africa. This species is therefore both primatophilic and anthropophilic. Since gorillas are the origin of the disease in humans, this species would have enabled the transmission of the infection from apes to humans thousands of years ago.

Discovery of what attracts pregnant mosquitoes is used to fight malaria

The battle against malaria is also a battle against its natural host, the mosquito, which means disrupting the insect's lifecycle is every bit as important as putting nets over beds. Now, an international research team has discovered what attracts mosquitoes to lay their eggs in specific places.

 

 

 

 

Some of the traps being tested with a substance that attracts female mosquitos looking for nesting spots to lay their eggs.

Credit: OviART

 

 

"We have been able to show that it is no coincidence where mosquitoes lay their eggs," says Jenny Lindh, a researcher from KTH Royal Institute of Technology. "They use both vision and their sense of smell."

With this finding, the research group OviART is designing mosquito traps that could help cut down the population of the genus, Anopheles, which is the primary vector of malaria.

Experimenting with different soil and water mixtures, the research team concluded that a constituent of earth found in breeding sites near Kenya's Lake Victoria -- a substance called cedrol -- is particularly attractive to the malarial mosquito, precisely at the time when the female is ready to ovulate.

Important mechanism involved in production of mosquito eggs identified

Diseases transmitted by mosquitoes have contributed to the death and suffering of millions throughout human history, earning the mosquito the title as the world's most dangerous animal. Even today, several devastating mosquito-borne diseases (such as malaria, dengue fever and West Nile virus) continue to rage.

The urgent need to better control mosquito numbers and interfere with disease transmission has guided much mosquito research in laboratories worldwide. Female mosquitoes rely on a blood-meal as a source of nutrients required for reproduction. The thinking is that if the mechanisms that govern mosquitoes' egg production are better understood, novel approaches to controlling the reproduction and population of mosquitoes can be devised.

Now a team of scientists at the University of California, Riverside has made a research breakthrough in understanding, at the molecular level, one such mechanism related to the mosquito reproductive process. This mechanism includes small regulatory RNA molecules known as microRNAs or miRNAs.

Hybrid 'super mosquito' resistant to insecticide-treated bed nets

Interbreeding of two malaria mosquito species in the West African country of Mali has resulted in a "super mosquito" hybrid that's resistant to insecticide-treated bed nets.

"It's 'super' with respect to its ability to survive exposure to the insecticides on treated bed nets," said medical entomologist Gregory Lanzaro of UC Davis, who led the research team.

The research, published Jan. 6 in the Proceedings of the National Academy of Sciences, "provides convincing evidence indicating that a man-made change in the environment -- the introduction of insecticides -- has altered the evolutionary relationship between two species, in this case a breakdown in the reproductive isolation that separates them," said Lanzaro, who is director of the Vector Genetics Laboratory and professor in the Department of Pathology, Microbiology and Immunology in the School of Veterinary Medicine.