March 6, 2013
Whitfield will be introduced by her former major professor, entomologist Diane Ullman, associate dean for undergraduate academic programs in the College of Agricultural and Environmental Sciences and a professor and former chair of the UC Davis Department of Entomology.
Whitfield received her master's degree in plant pathology from Ullman in 1999 and her doctorate in plant pathology from the University of Wisconsin, Madison, in 2004.
"Arthropod vectors play an essential role in dissemination of viruses that cause diseases in humans, animals, and plants," Whitfield says. "More than 70 percent of viruses infecting plants and 40 percent of viruses infecting mammals are transmitted from one host to another by arthropod vectors. My research is devoted to investigating plant-virus-vector interactions at the molecular level with the goal of developing a better understanding of the complex sequence of events leading to virus acquisition and transmission by vectors."
"Tomato spotted wilt virus (TSWV) is considered one of the ten most devastating plant viruses and is one of the viruses that we are working with to define the viral and vector determinants of transmission. The virus is transmitted by thrips (Thysanoptera: Thripidae), primarily Frankliniella occidentalis. The TSWV glycoproteins, designated GN and GC, are required for infection of thrips. We found that recombinant GN (GN-S) bound larval thrips midguts in a specific manner and inhibited TSWV acquisition and transmission (Whitfield et al., 2004, and Whitfield et al., 2008)."
"Our findings," Whitfield said, "provide evidence that GN serves as a viral ligand that mediates attachment of TSWV to receptors displayed on the epithelial cells of the thrips midgut. We generated transgenic tomato plants expressing a soluble form of GN with a GFP tag (GN-S::GFP) and found that thrips that fed on these transgenics had significantly lower virus titers and adult transmission efficiencies than thrips fed on TSWV-infected non-transgenic tomato plants. These results demonstrate that an initial reduction in virus infection of the larval insect midgut can result in a significant decrease in virus titer and transmission over the life-span of the vector. Despite the world-wide importance of thrips in agriculture, there is little knowledge of the F. occidentalis genome or gene functions at this time. We developed the first transcriptome analysis of F. occidentalis, and the partial thrips transcriptome was used to characterize the thrips proteome and response to virus infection (Rotenberg and Whitfield, 2010, Badillo-Vargas et al., 2012). Knowledge of thrips recognition and response to virus infection will enable us to develop new strategies to disrupt virus transmission."
Whitfield is the author of numerous publications and book chapters. She has published her work in the Journal of Virological Methods, Insect Molecular Biology, Journal of Virology and the Journal of Economic Entomology, among others.
--Kathy Keatley Garvey
Communications specialist
UC Davis Department of Entomology
(530) 754-6894
March 8, 2013
In his 224-page book, Page sheds light on how 40,000 bees, "working in the dark, seemingly by instinct alone, could organize themselves to construct something as perfect a a honey comb."
Page, now vice provost and dean of the Arizona State University's College of Liberal Arts and Sciences and Foundation Professor of Life Sciences, marvels at how bees can accomplish these incredible tasks. In synthesizing the findings of decades of experiments, he presents "a comprehensive picture of the genetic and physiological mechanisms underlying the division of labor in honey bee colonies and explains how bees' complex social behavior has evolved over millions of years," according to the Harvard University flier.
Page still keeps his specialized stock of honey bees at the Harry H. Laidlaw Jr. Honey Bee Research Facility at UC Davis. Bee breeder-geneticist Michael “Kim” Fondrk, who worked with Page at Ohio State University, UC Davis and ASU, manages the stock.
In his book, Page talks about the coordinated activity of the bees and how worker bees respond to stimuli in their environment. The actions they take in turn alter the environment, Page says, and "so change the stimuli for their nestmates. For example, a bee detecting ample stores of pollen in the hive is inhibited from foraging for more, whereas detecting the presence of hungry young larvae will stimulate pollen gathering."
Division of labor, Page says, is an inevitable product of group living because "individual bees vary genetically and physiologically in their sensitivities to stimuli and have different probabilities of encountering and responding to them."
Page, who received his doctorate in entomology at UC Davis in 1980, served as an assistant professor at Ohio State University before joining the UC Davis Department of Entomology in 1989. He chaired the department for five years, from 1999 to 2004.
In 2004--the year Page retired from UC Davis--ASU recruited him as the founding director and dean of the School of Life Sciences. At the time, his duties included organizing three departments—biology, microbiology and botany, totaling more than 600 faculty, graduate students, postdoctoral fellows and staff--into one unified school.
As its founding director, Page established the school as a platform for discovery in the biomedical, genomic and evolutionary and environmental sciences. He also established ASU’s Honey Bee Research Facility.
Page is a highly cited author on such topics as Africanized bees, genetics and evolution of social organization, sex determination, and division of labor in insect societies.
--Kathy Keatley Garvey
Communications specialist
UC Davis Department of Entomology
(530) 754-6894
March 8, 2013
The research, published March 8 in the PLOS ONE journal, shows that that “temperature effects on larval development time, larval survival and adult reproduction depend on the combination of mean temperature and magnitude of fluctuations,” said lead author Lauren Carrington, a former postdoctoral fellow in the Scott lab and CVEC.
The scientists investigated how realistic fluctuations in temperature during the day influence the life-history traits and population dynamics of the dengue mosquito, Aedes aegypti.
The research, “Effects of Fluctuating Daily Temperatures at Critical Thermal Extremes on Aedes aegypti Life-History Traits,” is expected to lead to greater accuracy of applications for mosquito surveillance and disease prevention.
“An improved understanding of mosquito responses to natural temperature variation,” Carrington said, “will enhance the effectiveness of vector control strategies, thereby reducing transmission of mosquito-borne diseases, such as dengue fever.” By using constant temperatures, scientists can under- or -over estimate values, she said.
“In the field, mosquitoes, and other insects, are exposed to a constantly changing environment, with fluctuations in temperature throughout the day, every day. In the lab, however, experimental protocols generally try to minimize as much variability as possible, and temperature is often the first element to be standardized.”
“After assessing a number of life-history traits at constant temperatures ranging from 12ºC-40ºC to identify the thermal limits of this population of mosquitoes from Thailand, we then reexamined the same traits under cyclic temperatures around a low (16ºC), intermediate (26ºC) and high (35ºC) mean temperature and compared these to appropriate constant temperature controls,” Carrington said.
“The results of our study are extremely important because they provide a better understanding of the life history traits and ecology of the vector, Aedes aegypti, said co-author Veronica Armijos, a Ph.D student with CVEC who studies with major professor William Reisen and works part-time in the Scott lab. “Information like this can be used to help improve current vector control and surveillance strategies."
Research team member Christopher Barker, an assistant adjunct professor with CVEC, part of the UC Davis School of Veterinary Medicine’s Department of Pathology, Microbiology, and Immunology, generated “a stage-structured population dynamic model using our empirical data,” Carrington said. “The model predicted that growth rates could be over- or under-estimated relative to constant temperatures, dependent upon the mean and magnitude of the fluctuations.”
“This is an important addition to a growing body of evidence showing that average temperatures are inadequate to explain variation in mosquito development and reproduction in natural systems,” Barker said. “This study demonstrated additional effects of an often-ignored second dimension-- daily cycling between nighttime lows and daytime highs--particularly when average temperatures were near the limits for mosquito survival.”
“These findings are important in the context of climate change because globally, nights have warmed faster than days, and the changes have been quite pronounced in the ‘urban heat islands’ preferred by Aedes aegypti,” Barker said. “As a result, overall warming trends have been accompanied by reduced daily temperature ranges, and understanding the roles of both will be important for predicting future impacts on mosquito populations.”
Said Carrington: “Our results have epidemiological significance for dengue transmission dynamics, and more generally, highlight that it is not always appropriate to extrapolate the results from laboratory-based experiments directly into the field. Sometimes, allowing for the environmental variation that we as scientists usually try to minimize, is actually important for understanding the ecology of a species in the wild.”
Carrington, Armijos, Barker and Thomas Scott, professor of entomology and director of the Mosquito Research Laboratory, co-authored the paper with Louis Lambrechts, a former Scott lab postdoctoral associate who is now with Insects and Infectious Diseases, Institut Pasteur, France.
Dengue is spread by an infected female Aedes aegypti mosquito, a day-biting, limited flight-range mosquito that prefers human blood to develop its eggs. Dengue is caused by four distinct, but closely related, viruses and the most severe form of disease is life-threatening dengue hemorrhagic fever or DHF.
Some 500,000 people with severe dengue are hospitalized each year, according to the World Health Organization (WHO), and about 2.5 percent of those affected die.
“Dengue takes an enormous toll on human health worldwide, with as many as 4 billion people at risk—half of the world’s population--and 400 million new infections each year,” Scott said.
The National Science Foundation’s Ecology of Infectious Diseases Program funded the project.
--Kathy Keatley Garvey
Communications specialist
UC Davis Department of Entomology
(530) 754-6894
Feb. 28, 2013
This is a fundraiser for the Partners for Sustainable Pollination and will take place from 8:30 am. to 4:30 p.m. in the Sebastopol Center for the Arts, located in the Veterans' Building, 282 South High St., Sebastopol. The theme is "Pollinator Habitat and Forage."
Williams will speak on "Development of Wildflower Mixes to Promote Native Pollination in Agriculture."
A core faculty member in the UC Davis Agricultural Sustainability Institute, Williams focuses his research on pollination that spans the disciplines of conservation biology, behavioral ecology and evolution. One of his primary research foci is on sustainable pollination strategies for agriculture. This work is critical given ongoing pressures facing managed honey bees and reported declines in important native pollinators such as bumble bees.
He and his colleagues explore the role of wild native bees, honey bees and other managed species as crop pollinators and the effects of landscape composition and local habitat quality on their persistence.
They explore:
- Under what contexts can native pollinators provide sufficient pollination for different crop? The answer to this question helps alleviate the stress placed on honeybees and also informs ways to more sustainably manage agricultural systems to promote biodiversity and production.
- How can we enhance habitat and diversify agricultural systems to promote managed and wild bees?
- Do pollinators interact in ways to increase the overall effectiveness of crop pollination?
A continuing goal is to provide practical information that can be used to improve the long term stability of pollination for agriculture in California, as well as promote pollinator conservation and management.
Other speakers at the symposium will include bee industry expert Peter Borst of Biomedical Sciences, Cornell University. He will give two talks: "A Short History of Pollination" and "Pollinator Panorama." Borst is a regular contributor to the American Bee Journal.
Professor Gordon Frankie of UC Berkeley will discuss "Bees and Flowers: A Selective Love Affair.”
Master Gardener Cheryl Verettto will share “Plant 4 Bees: Help The Bees by Planting All 4 Seasons”
Farmer Paul Kaiser of the Singing Frogs Farm will cover “Farming For Pollinators: How Can We Humans Produce Nutrient Dense Food While Improving the health, Vitality and Resiliency of Mother Nature?”
Coffee, tea, water and assorted treats will be available. The lunch break is from noon to 1:30 on site (Fork Truck Catering, fresh organic food) or participants may dine at local restaurants within walking distance, a spokesperson said.
Tickets are $35 pre-sale or $45 at the door. Members receive a $5 discount. For more information or to purchase tickets, access http:// www.pfspbees.org/store or cash tickets may be purchased at Beekind, 921 Gravenstein Highway South., Sebastopol.
For general information, contact Jeanine Robbins at jeaninepfsp@gmail.com or (707) 824-2905.
--Kathy Keatley Garvey
Communications specialist
UC Davis Department of Entomology
(530) 754-6894
Feb. 26, 2013
Hoover will speak from noon to 1 p.m. in 122 Briggs Hall (this was initially set for 366 Briggs.) She will be in California in conjunction with her trip to Ventura to participate in the Gordon Research Conference, an international forum for the presentation and discussion of frontier research in the biological, chemical, and physical sciences, and their related technologies.
“The gypsy moth has a long co-evolutionary history with its host specific baculovirus, Lymantria dispar NPV,” Hoover said. “As a result, the gypsy moth has evolved counter-defenses against the virus, while in return the virus has strategies for increasing its own fitness at the expense of the host. For example, anti-viral defenses include apoptosis of infected cells (despite viral inhibitor of apoptosis genes), while the virus manipulates host behavior to enhance transmission to new hosts, which is an example of the extended phenotype.”
Hosts are Bruce Hammock, distinguished professor of entomology; Michael Parrella, professor and chair of the UC Davis Department of Entomology and Nematology; and researcher George Kamita of the Hammock lab.
Hoover received her doctorate in entomology from UC Davis in 1997 and as a graduate student, was co-advised by major professors Bruce Hammock and Sean Duffey (1943-1997). After a one-year postdoctoral position at UC Berkeley, she joined the faculty of the Penn State University Department of Entomology in 1998.
Her research program focuses on invasive species, including development of trapping techniques for the Asian longhorned beetle; gut microbial symbionts of the Asian longhorned beetle and hemlock woolly adelgid; functions of key viral genes in transmission of the gypsy moth baculovirus and anti-viral defenses; and biological control of hemlock woolly adelgid.
Hoover is the lead author of the highly acclaimed research, “A Gene for an Extended Phenotype,” published Sept. 9 in Science. It was selected for the Faculty of 1000 (F1000), which places her work in its library of the top 2 percent of published articles in biology and medicine.
The abstract:
"Manipulation of host behavior by parasites and pathogens has been widely observed, but the basis for these behaviors has remained elusive. Gypsy moths infected by a baculovirus climb to the top of trees to die, liquefy, and 'rain' virus on the foliage below to infect new hosts. The viral gene that manipulates climbing behavior of the host was identified, providing evidence of a genetic basis for the extended phenotype." The research was co-authored by Michael Grove, Matthew Gardner, David Hughes, James McNeil and James Slavicek.
Hoover received her bachelor’s degree from UC Berkeley in 1979 and her master’s degree in 1992 from San Jose State University.
--Kathy Keatley Garvey
Communications specialist
UC Davis Department of Entomology
(530) 754-6894
