- 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
The species has spread to at least seven counties in California since June 2013, says UC Davis medical entomologist Anthony Cornel of the UC Kearney Agricultural Research and Extension Center, Parlier, and the UC Davis Department of Entomology.
“It's an issue of great concern, especially as current control methods do not appear to be working well," says Cornel, who collaborates on research projects in Clovis, Fresno County, with the Consolidated Mosquito Abatement District. The district, based in Fresno, covers 1,058 square miles, including part of Kings County.
“We can't predict how far this mosquito will go in California,” he says, but it has spread “south of Fresno to San Diego. The furtherest site north is Madera in the Central Valley, but it's also been found in the more coastal area of Menlo Park in San Mateo.”
As far north as Sacramento?
“I don't want to exclude the possibility that it may spread as far north as Sacramento,” said Cornel, who collects, rears and researches mosquitoes from all over the world, including the United States, Mali, Cameroon, Comoros, Tanzania, South Africa and Brazil. “We need to see if it overwinters as eggs or adults or both.”
Infected Aedes aegypti can transmit dengue, yellow fever, Zika and chikungunya viruses. The Zika virus was first identified in Uganda in 1947 in rhesus monkeys, according to the World Health Organization. It was subsequently identified in humans in 1952 in Uganda and the United Republic of Tanzania. Outbreaks of Zika virus disease have been recorded in Africa, the Americas, Asia and the Pacific.
Although the mosquito species is in California, it's important to point out that there are no reported cases of locally transmitted Zika virus in the state or in contiguous United States, according to the Centers for Disease Control and Prevention. The cases have all involved travelers returning home from countries plagued with disease outbreaks.
Cornel and his colleagues published a 27-slide document, “Surveillance and Control of Aedes aegypti Mosquito in Clovis, Calif.,” on Feb. 8 in F1000 Research, http://f1000research.com/slides/5-149. They called attention to the widespread invasion and establishment of the species in California. The research, illustrated with maps, is the work of Cornel and Yoosook Lee of UC Davis; Stephen Dobson of the University of Kentucky; Corey Bansfield of MosqMate Inc. and Jodi Holeman, Mark Amireno, Charles Smith and Stephen Mulligan III of the Consolidated Mosquito Control District.
The California team collaborates with University of Kentucky scientists to develop novel control strategies. One trial involves coating male mosquitoes with insect growth regulators, which are passed on to the females. Males are also infested with a biopesticide or “a good bacteria-like organism,” Wolbachia. “The male transfers it to the female, which affects the ovaries and negatively affects immature development,” Cornel explains. “It's not new, but it's not been employed in large trials.”
The researchers target mosquito breeding sites, primarily yard drains. “Despite the drought and the elimination of visible bodies of water, such as bird baths, pet bowls and flower pots, there's a major issue: yard drains,” Cornel says. “Yard drains installed in new home developments empty into the gutter or street and are cryptic breeding sites for mosquitoes.” He speculates that these mosquitoes are breeding underground.
“These drains are not easily accessible and we can't see the mosquitoes,” Cornel points out. “We need to blow out the water and plug these yard drains to eliminate these breeding sites.” He suggests that cities everywhere address this public safety issue and “redesign the yard drains.”
It's crucial for the public to become involved, Cornel emphasizes. “We have to focus on public education. We have to get the message across to eliminate mosquito breeding sites. We can't go to every house. We must rely on the public to eliminate the breeding sites.”
It's possible—but he hopes not—that what is now a “mosquito nuisance” will result in a disease outbreak.
- 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.
