Posts Tagged: Anopheles gambiae
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.
Medical entomologist Laura Norris (right side of table, second from top) works with a night's catch of mosquitoes in Mali.
UC Davis medical entomologist Anthony Cornel (left) emerges from a hut in Mali.
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.
The malaria mosquito, Anopheles gambiae. (Photo by Anthony Cornel)