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
DAVIS--Paramjit Kaur of India who was a visiting scholar in the Frank Zalom lab last summer and fall, won “Best Poster Presentation” at the fourth International Conference on Insect Science, held in Bangalore, India.
She titled her poster--research co-authored by Zalom--“Prey Preference of the Predatory Mite, Neoseiulus californicus McGregor for Tetranychus urticae Koch and Eotetranychus lewisi (McGregor) on Strawberry at Different Temperatures.”
Kaur is an assistant professor of acarology at Punjab Agricultural University in Ludhiana, India. The Indian Society for the Advancement of Insect Science sponsored the conference.
The two-spotted mite, Tetranychus urticae, is a key pest of strawberries in California. The Lewis mite, Eotetranychus lewisi, is an emerging problem in southern California strawberry production, Kaur wrote.
In a note to integrated pest management specialist Zalom, professor of entomology, Kaur credited him for his support and guidance. She wrote: “I am so happy for this valuable achievement. This all happened due to your support and guidance. I am really thankful to you for providing me best opportunity to work with you. Again, I am thankful to you for providing me space in your lab. The time spent in Davis was the best time in my life. Thanks a lot.”
--Kathy Keatley Garvey
Communications specialist
UC Davis Department of Entomology
(530) 754-6894
Feb. 20, 2013
Assistant professor Joanna Chiu will host the seminar, which is scheduled to be recorded for later viewing on UCTV.
About her research and her upcoming seminar, Dahanukar says: "We are interested in the molecular neurobiology of feeding behavior. Insects use highly diverse groups of gustatory receptors (Grs) to taste the chemical world and determine the palatability of potential food sources. In Drosophila melanogaster, the 68 receptors of this family are expressed in complex combinatorial patterns in taste neurons. In previous studies we and others identified a highly conserved clade of eight Gr genes that encode sugar receptors. Although some of these have been linked to detection of sweet compounds by genetic analysis, their precise functions are still poorly understood. Little is also known about how stimuli that are typically not rich in sugars trigger highly attractive gustatory responses in Drosophila."
"We have also obtained functional expression of a taste receptor from the mosquito Anopheles gambiae in Drosophila. We are now poised to further investigate taste detection and Gr function in Drosophila and other insects."
Among her honors, Dahanukar received a National Science Foundation Career Award in 2012; the Whitehall Foundation Award in 2011; the 2000 Ruth L. Kirschstein National Research Service Award. She was awarded a Government of India National Merit Scholarship in 1990.
She holds a bachelor of science degree in life sciences in 1990 from the Bombay University, India; a master's degree in environmental management from Duke University; and a doctorate in genetics in 1999 from Duke University, where she studied patterning along the anterior-posterior axis in Drosophila embryos. In 1999, she joined the laboratory of John Carlson at Yale University to pursue post-doctoral training in the molecular neurobiology of insect chemosensory systems. Dahanukar joined the faculty of the UC Riverside Department of Entomology in 2009.
Among her latest publications:
2011
Wisotsky, Z., Medina, A., Freeman, E. & Dahanukar, A. Evolutionary
differences in food preferences rely on Gr64e, a receptor for glycerol. Nat
Neurosci 14(12): 1534-1541.
Kwon, J.Y., Dahanukar, A., Weiss, L.A. & Carlson, J.R. Molecular and cellular
organization of the taste system in the Drosophila larva. J Neurosci 31(43):
15300-15309.
Weiss, L.A., Dahanukar, A., Kwon, J.Y., Banerjee, D. & Carlson, J.R. The
molecular and cellular basis of bitter taste in Drosophila. Neuron 69(2): 258-
272.
Dahanukar, A. & Ray, A. Courtship, aggression and avoidance: Pheromones,
receptors and neurons for social behaviors in Drosophila. Fly 5(1): 58-63.
2010
Benton, R. and Dahanukar, A. Chemosensory coding in single sensilla. In
“Drosophila neurobiology methods: A companion to the Cold Spring Harbor
Neurobiology of Drosophila course,” Scott Waddell, Bing Zhang and Marc
Freeman (ed.), CSHL press. pp.247-276.
2007
Dahanukar, A., Lei, Y-T., Kwon, J. Y. and Carlson, J.R. Two Gr genes
underlie sugar reception in Drosophila. Neuron 56(3):503-516.
Kwon, J.Y., Dahanukar, A., Weiss, L.A. & Carlson, J.R. The molecular basis
of CO2 reception in Drosophila. Proc Natl Acad Sci U S A 104(9):3574-3578.
2006 Hallem, E. A., Dahanukar, A., and Carlson, J. R. Insect odor and taste
receptors. Annu Rev Entomol 51: 113-135.
2005
Coelho, C. M., Kolevski, B., Bunn, C., Walker, C., Dahanukar, A., and
Leevers, S. J. Growth and cell survival are unevenly impaired in pixie mutant
wing discs. Development 132(24): 5411-5424.
Dahanukar, A., Hallem, E. A., and Carlson, J. R. Insect chemoreception. Curr
Opin Neurobiol 15(4): 423-430.
--Kathy Keatley Garvey
Communications specialist
UC Davis Department of Entomology
(530) 754-6894
