- Author: Kathy Keatley Garvey
And well it should.
Research led by UC Davis medical entomologists and published in the Sept. 15 edition of PLOS Genetics, indicates "a genetic component" to the blood-feeding behavior and host choice of Anopheles arabiensis.
The research was done in Kilombero Valley in Tanzania.
"We know that blood feeding preference among mosquitoes can be species specific,” said co-author and professor Greg Lanzaro, who leads the Vector Genetics Laboratory, UC Davis Department of Pathology, Microbiology and Immunology and is an affiliate of the UC Davis Department of Entomology and Nematology. “For example, there are mosquito species that specialize in feeding on amphibians or reptiles. We also know that many species are more catholic when choosing a meal and this can have important implications to human health—it's how some disease agents move between animals and humans.”
The publication, titled "The Genetic Basis of Host Preference and Resting Behavior in the Major African Malaria Vector, Anopheles arabiensis, is the work of a 13-member international team.
Medical entomologist and co-author Anthony Cornel of the UC Davis Department of Entomology and Nematology faculty--his lab is based at the Kearney Agricultural Research and Extension Center in Parlier--had this to say about the significance of the research: "From my perspective I would state that environmental anthropogenic influences by replacing natural habitats for human dwelling, need for more food and water by creating more agricultural lands and changing local water patterns, increasing domestic animal rangeland and use of insecticides can have quite dramatic influences of disease vector behavior and their genetic diversity. These changes should be monitored in the overall context of how these mosquito adaptations influence disease transmission dynamics.”
Other co-authors are researchers Yoosook Lee, Heather Ferguson, Travis Collier, Catelyn Nieman, Allison Weakley, all of the Vector Genetics Lab; Katharina Kreppel, Nicodem Govella and Anicet Kihonda of the Ifakara Health Institute, Ifakara, United Republic of Tanzania; and computer scientists Eleazar Eskin and Eun Yong Kang of UCLA.
Their summary?
“Malaria transmission is driven by the propensity for mosquito vectors to bite people, while its control depends on the tendency of mosquitoes to bite and rest in places where they will come into contact with insecticides. In many parts of Africa, where coverage with Long Lasting Insecticide Treated Nets is high, Anopheles arabiensis is the only remaining malaria vector. We sought to assess the potential for An. arabiensis to adapt its behavior to avoid control measures by investigating the genetic basis for its host choice and resting behavior. Blood-fed An. arabiensis were collected resting indoors and outdoors in the Kilombero Valley, Tanzania. We sequenced a total of 48 genomes representing 4 phenotypes (human or cow fed, resting in or outdoors) and tested for genetic associations with each phenotype. Genomic analysis followed up by application of a novel molecular karyotyping assay which revealed a relationship between An. arabiensis that fed on cattle and the standard arrangement of the 3Ra inversion. This is strong support that An. arabiensis blood-feeding behavior has a substantial genetic component. Controlled host choice assays are needed to confirm a direct link between allelic variation within the 3Ra inversion and host preference.”
You can read the paper online in PLOS Genetics.
- Author: Kathy Keatley Garvey
It's good to see UC Davis mosquito researchers featured in the KQED's science program, "Deep Look."
KQED journalists recently traveled to the UC Davis campus to visit several mosquito labs. The end result: The KQED news article on “How Mosquitoes Use Six Needles to Suck Your Blood,” which includes an embedded video. The National Public Radio's health blog, “Shots,” includes a shorter version. You can also see the Deep Look video on YouTube (embedded below).
- Parasitologist and entomologist Shirley Luckhart, professor in the UC Davis School of Medicine's Department of Medical Microbiology and immunology and the Department of Entomology and Nematology
- Medical entomologist Gregory Lanzaro, professor, Department of Pathology, Microbiology and Immunology (PMI), UC Davis School of Veterinary Medicine, and an associate of the UC Davis Department of Entomology and Nematology
- Chemical ecologist Walter Leal, professor in the UC Davis Department of Molecular and Cellular Biology and former chair of the UC Davis Department of Entomology
- Virologist Lark Coffey of PMI
- UC Davis post-doctoral researcher Young-Moo Choo of the Leal's lab who discovered a receptor by dissecting mosquitoes' mouthparts and genetically testing them.
“Mosquitoes don't find the blood vessel randomly," Leal said, pointing out that the receptors respond to chemicals in the blood.
The receptor that the Leal lab discovered is called 4EP, and may lead to drug companies developing new mosquito repellents. “First they'd need to find a repellent against the receptors," Choo told Quirós. "Then they'd treat people's skin with it. When the mosquito tried to penetrate the skin, it would taste or smell something repulsive and fly away.”
But back to the video. The narrator reveals the sophisticated tools that the mosquito uses to draw your blood.
- A protective sheath retracts: inside are six needles, and two of them have sharp, tiny teeth
- The mosquito uses the sharp, toothed needles to saw through your skin
- Other needles hold the tissues apart while she works
- Receptors on the tip of one of her needles guide her to your blood vessel.
- She uses the same needle like a straw to sip your blood
- She uses another needle to spit chemicals into you so your blood will flow easily. That's what gives you the itchy, scratch-me-now welts.
Of course, it's the viruses or parasites that the mosquito transmits that can sicken and kill us. Depending on the species, they give us such diseases as malaria, dengue, yellow fever, West Nile virus, Zika virus and elephantiasis.
As KQED says "This is the deadliest animal in the world. Mosquitoes kill hundreds of thousands of people each year...the most vulnerable people: children and pregnant women."
KQED performed an excellent public service in reporting and sharing this scientific information, gleaned from the UC Davis labs. The first day the video was posted, it drew nearly 400,000 views.
We worry about what mosquitoes do to us. If mosquitoes could talk--if they could communicate with us--they ought to be worried about what we're going to do to them.
(Access the American Mosquito Control Association website to learn the biology of mosquitoes.)
- Author: Kathy Keatley Garvey
It was just a matter of time before the so-called "super mosquito" surfaced, resulting in the failure of insecticide-treated nets to provide meaningful control from malaria in some localities in Africa.
"It's a ‘super' with respect to its ability to survive exposure to the insecticides on treated bed nets,” said medical entomologist Gregory Lanzaro, director of the Vector Genetics Laboratory at the School of Veterinary Medicine, University of California, Davis, who led the research team.
He and his colleagues recently discovered that 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.
Anopheles gambiae, a major malaria vector, is interbreeding with isolated pockets of another malaria mosquito, A coluzzii.
The research, published 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, a professor in the Department of Pathology, Microbiology and Immunology in the School of Veterinary Medicine.
Lanzaro and his "blood brother" medical entomologist Anthony Cornel of the Department of Entomology and Nematology have been researching mosquitoes in Mali since 1991.
Lanzaro called the need to develop new and effective malaria vector control strategies "urgent.”
Said Lanzaro: "A number of new strategies are in development, including new insecticides, biological agents--including mosquito killing bacteria and fungi--and genetic manipulation of mosquitoes aimed at either killing them or altering their ability to transmit the malaria parasite. These efforts need to be stepped up.”
The paper is titled “Adaptive Introgression in an African Malaria Mosquito Coincident with the Increase Usage of Insecticide-Treated Bed Nets.” First author is Laura Norris, then a postdoctoral scholar in the UC Davis Department of Entomology and Nematology who was supported by a National Institutes of Health T32 training grant awarded to Lanzaro. Norris has since accepted a position with the President's Malaria Initiative in Washington, D.C.
In addition to Lanzaro and Cornel, the co-authors include Yoosook Lee and Travis Collier of the Vector Genetics Lab and the Department of Pathology, Microbiology and Immunology; and Abdrahamane Fofana of the Malaria Research and Training Center at the University of Bamako, Mali. Three grants from the National Institutes of Health funded the research.
- Author: Kathy Keatley Garvey
"Every 45 seconds a child in Africa dies from malaria, a disease spread by a single mosquito bite. There are more than 200 million cases of malaria each year, and nearly 1 million of those infected die from the disease — most of them children under the age of five."
That's on the Nothing But Nets website and there's something we can all do to help. We can donate $10 for a life-saving bed net to protect families in Africa from getting bit by a mosquito.
There's something else we can do: attend the third annual Bay Area World Malaria Day Symposium, set for 8 a.m. to 3 p.m., Friday, April 25 on the Clark Kerr campus, UC Berkeley.
It promises to be a day of innovation, knowledge-sharing and collaboration, announced Kay Monroe of Zagaya, the event host. The schedule of events will be presented the day of the symposium.
Lanzaro's Soundbite presentation,"Malaria in the Americas: A New Research Initiative for the UC Davis Vector Genetics Lab," will key in on the challenges of malaria control in Brazil. Lee's Soundbite presentation will be on a new diagnostic tool for malaria mosquito research. Luckhart is scheduled for both a Soundbite and poster.
Two of the UC Davis presenters, Laura Norris and Bradley Main, are National Institutes of Health T32 postdoctoral fellows. They will cover the topic of malaria vector evolution in the face of insecticide pressure from bed net campaign.
The list of the other UC Davis presenters, as announced by Monroe:
Nazzy Pakpour, Soundbite; and Elizabeth Glennon, Kristen Lokken, Jason Maloney, Jose Pietri, Rashaun Potts and Lattha Souvannaseng, Bo Wang, poster.
Keynote speakers are:
- Tim Wells, chief scientific officer, Medicines for Malaria Venture, Geneva, Switzerland, who will share the latest efforts to develop new drugs aimed at wiping out malaria.
Title: The Pipeline of Medicines to Support Malaria Control and Elimination
View abstract - Joseph DeRisi, professor and vice chair of the Department of Biochemistry and Biophysics, UC San Francisco, and a Howard Hughes Medical Institute investigator, who will talk about work in his lab.
Title: "A View from the Trenches – Anti-malarial Drug Development"
View abstract - Regina Rabinovich, ExxonMobil Malaria Scholar in Residence at the Harvard School of Public Health, who will examine the future of malaria eradication efforts, past the 2015 UN Millennium Development goals.
Title: "Beyond the Millennium Development Goals Horizon – What Will Help Drive Success Post-2015?"
View abstract
Officials at Zagaya (which means "spear") say this is a critical time for malaria research professionals to come together, as it's one year away from the 2015 UN Millennium Development goal of halting and reversing the growth of malaria incidence. The symposium provides the forum for researchers, implementers, advocates and students to "inspire and catalyze change for the greater good."
Registration is open and ongoing until the day of the event. General registration is $50, and students, $25. A portion of the registration fee--$10--will go toward purchasing bed nets via the United Nation's Nothing but Nets program, a global, grassroots campaign to save lives by preventing malaria.
The nets are considered one of the most cost-effective tools to prevent the spread of malaria. How effective? Statistics show that bed nets can reduce malaria transmissions by 90 percent in areas with high coverage rates.
