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.