- 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 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
Bradley White, assistant professor at UC Riverside, will speak on “Ecological Genomics of Malaria Mosquitoes” at the UC Davis Department of Entomology seminar from 12:05 to 1 p.m. in Room 1022 of the Life Sciences Building, corner of Hutchison and Kleiber Hall drives.
Professor Gregory Lanzaro of the UC Davis School of Veterinary Medicine will introduce White. Plans call for video-recording the seminar for later posting on UCTV.
"Anopheles gambiae is the most important malaria vector in the world,” White says in is abstract. “Remarkable adaptive flexibility has enabled this mosquito to track humans across the diverse ecoclimates of sub-Saharan Africa where it thrives in both highly mesic and xeric conditions. These rapid, recent ecological adaptations have driven incipient speciation into two ecotypes, which differentially exploit permanent and temporary larval habitats. Within each nascent species, abundant chromosomal inversion polymorphisms facilitate adaptation to local conditions along latitudinal environmental gradients."
“To elucidate the genetic basis of ecological adaptation in Anopheles gambiae, we performed a series of genome-wide divergence scans, which revealed candidate regions subject to recent natural selection. Dissection of one of these genomic regions established a link between naturally occurring allelic variation and an adaptive phenotype. In the context of evolutionary genomics, these studies shed light on the maintenance of inversion polymorphisms and also provide insight into the genomic architecture of reproductive isolation. From a public health standpoint, this work demonstrates how divergent ecological selection can impact the vectorial capacity of Anopheles gambiae -- with consequences for malaria epidemiology and control.”
White began working on mosquitoes as an undergraduate at Oberlin College in Ohio. “At the time, West Nile virus (WNV) was sweeping through the midwest and during the summers I participated in a project to identify the Culex vectors of WNV and to determine environmental factors affecting their abundance,” he said. “After leaving Oberlin, I spent the next seven years in Nora Besansky's lab at Notre Dame where I focused on the population genomics of the African malaria mosquito Anopheles gambiae."
White, who joined the UC Riverside Department of Entomology faculty in 2011, focuses his research on quantitative and functional genomics of Anopheline malaria vectors.
More information? Check out his website at http://www.mosquitogenomics.org.
- Author: Kathy Keatley Garvey
Mark your calendars for a sobering experience.
The University of California,Davis, will observe World Malaria Day with a daylong retreat showcasing UC Davis scientists’ current research in vector biology and genetics.
The event, free and open to the public, will take place from 9 a.m. to 4 p.m., Monday, April 25 in Room 1102 of the Gourley Clinical Teaching Center, School of Veterinary Medicine, on Garrod Drive.
Malaria is a killer. "Approximately half of the world's population is at risk of malaria, particularly those living in lower-income countries," according to the World Health Organization (WHO). "It infects more than 500 million people per year and kills more than 1 million. The burden of malaria is heaviest in sub-Saharan Africa but the disease also afflicts Asia, Latin America, the Middle East and even parts of Europe."
Postdoctoral researchers Becky Trout (rttrout@ucdavis.edu) and Michelle Sanford (mrsanford@ucdavis.edu) are organizing the event, and issued this statement: “Malaria remains one of the most deadly vectorborne diseases in the world. Worldwide programs continue to rely on control programs based on the most recent research available. In honor of the Roll Back Malaria Program, promoting the education and research in the fight against malaria, student and researchers at UC Davis engaged in vector biology and genetics will come together to discuss their research efforts.”
During the breaks and during lunch, attendees will see a photo slide show of research experiences.
Malaria researchers associated with the UC Davis Department of Entomology include graduate student advisors Anthony “Anton” Cornel, associate professor, Department of Entomology; Shirley Luckhart, professor, Department of Medical Microbiology and Immunology, UC Davis School of Medicine; and Gregory Lanzaro, professor, Department of Pathology, Microbiology and Immunology, School of Veterinary Medicine.
Through their research and public involvement, they're all doing their part to control a killer.
- Author: Kathy Keatley Garvey
Malaria is indeed a global terrorist.
The disease, caused by the parasite Plasmodium and transmitted by infected anopheline mosquitoes, strikes some 350 to 500 million people a year, killing more than a million individuals, primarily in Africa, according to the Centers for Disease Control and Prevention.
So, it's good news to hear that malaria researcher Win Surachetpong, a doctoral candidate in the Shirley Luckhart lab at UC Davis, is the 2009 winner of the William C. Reeves New Investigator Award, given to the best scientific paper presented at the annual Mosquito and Vector Control Association of California (MVCAC) meeting.
Surachetpong received $1000 and a plaque at the 77th annual MVCAC meeting, held in
“His work,” she said, “has been the foundation of the development of a completely new area of work for us that will probably keep us busy for years to come." On a personal note, Win is a good friend to everyone in the lab and always ready with a quick smile and good word for the day."
The award memorializes William C. Reeves, a renowned entomologist and professor at UC Berkeley who was widely regarded as the world's foremost authority on the spread and control of mosquito-borne diseases. Reeves (1916-2004) was a frequent visitor to the UC Davis campus.
Surachetpong said that malaria “remains an enormous public health burden, especially in developing countries.”
“New strategies including integrated vector management in combination with current conventional malaria control efforts such as drug treatment and bednet usage could synergistically reduce malaria transmission,” Surachetpong said.
“However, our current knowledge of vector-host-parasite interactions is limited,” he noted. “For example, how mosquito innate immune responses control malaria parasite development and how blood-derived factors modulate mosquito biology remain interesting topics.”
“In this study, we reveal the role of MEK-ERK (mitogen-activated protein kinase/extracellular signal-regulated kinase) signaling in regulation of malaria parasite development by an ingested blood-derived, mammalian cytokine in the mosquito host.”
The results, the researchers said, “provide new insights into the host-parasite-vector relationship that could be utilized as a foundation for new strategies to reduce malaria transmission.”
A native of
Last year Surachetpong was awarded a prestigious Bill and Melinda Gates Foundation health travel award to present his research at a Keystone Symposia conference in Bangkog, Thailand. The meeting focused on the pathogenesis and control of emerging infections and drug-resistant organisms.
Surachetpong received his doctorate of veterinary science at
