Rick Karban

This is a meeting of the Davis Botanical Society, which begins at 6:45 p.m. President Marie Jasieniuk will announce the 2014 student grant recipients and the members will elect new officers. All interested persons are invited. The library is located at 315 E. 14th St.

Karban will discuss the rarely studied phenomenon of communication between plants, announced plant taxonomist Ellen Dean, curator, Center for Plant Diversity. "For a number of years, Dr. Karban has been studying plant-to-plant communication in big sagebrush (Artemisa tridentata) at Sagehen Creek in the Sierrra Nevada. His research has shown that volatile compounds are released from injured plants and that these compounds are detected by nearby plants, allowing them to better defend themselves against herbivores and other predators."

Excerpts from a news release published Feb. 13, 2013 by the UC Davis Department of Entomology and Nematology:

If you're a sagebrush and your nearby kin is being eaten by a grasshopper, deer, jackrabbit, caterpillar or other predator, it's good to be closely related. Through volatile (chemical) cues, your kin will inform you of the danger so you can adjust your defenses.

If you're not closely related, communication won't be as effective.

Newly published research in today's Proceedings of the Royal Society B: Biological Sciences shows that kin have distinct advantages when it comes to plant communication, just as “the ability of many animals to recognize kin has allowed them to evolve diverse cooperative behaviors,” says lead researcher and ecologist Richard Karban, a professor in the UC Davis Department of Entomology.

For example, fire ants can recognize kin. “Ants will destroy queens that are not relatives but protect those who are,” Karban said.

That ability is less well studied for plants, until now.

“When sagebrush plants are damaged by their herbivores, they emit volatiles that cause their neighbors to adjust their defenses,” Karban said. “These adjustments reduce rates of damage and increase growth and survival of the neighbors.” See more.

Stacy Hishinuma (Photo by B. Korhely)

Hishinuma, who is completing her doctorate, studies the walnut twig beetle, Pityophthorus juglandis, which in association with a newly described fungus, Geosmithia morbida, causes thousand cankers disease (TCD) of walnut and butternut trees.

Hishinuma works with major professor Mary Louise Flint and is co-advised by chemical ecologist and forest entomologist Steve Seybold of the Pacific Southwest Research Station, USDA Forest Service, Davis, an affiliate of the department.  Flint is an Extension specialist emeritus with the UC Davis Department of Entomology and Nematology and a former associate director with the UC Integrated Pest Management Program.

“USDA will provide some financial support during the end stages of her Ph.D. thesis, in exchange for 320-640 hours of work and training over the next 14 months,” said Seybold. Then, in June 2016 her position will be converted to that of a permanent entomologist with the USDA Forest Service office in San Bernardino after she has completed her thesis. She will be responsible for forest insect survey, detection, and management on four national forests in southern California ranging from San Diego to Monterey counties.

“The highly competitive internship and guaranteed position are a credit to her and her achievements,” Seybold said.

Seybold and Flint assisted her in developing the internship, as did Richard “Rick” Bostock, UC Davis professor of plant pathology.

Hishinuma won the 2013 Western Forest Insect Work Conference Memorial Scholarship for her research on TCD and presented her work at group's 65th annual conference, held March 31-April 3, 2014 in Sacramento.  She also received two scholarships from the California Garden Clubs, Inc. (CGCI) and a McBeth Memorial Scholarship to support her research on TCD.

The walnut twig beetle is believed to be native to Arizona, California, New Mexico and Mexico.  In 2006, plant pathologist Ned Tisserat and entomologist Whitney Cranshaw of Colorado State University identified the pathogen in declining black walnut trees in central Colorado. The disease has now spread east of the Mississippi to states in the heart of the valuable black walnut timberlands. Most recently it was reported from Indiana. Latest collection records show that the beetle and pathogen are now known from nine states in the western United States and seven states in the eastern USA.  In 2013 the disease was also reported in Italy marking the first time that it occurred in Europe.   

Seybold's research group has led the effort to characterize the disease in California and to develop a nationwide detection program for the beetle. They recently published two papers in the journal PLOS ONE that characterize the genetic diversity and invasion patterns of both the pathogenic fungus and the beetle in the United States. Scientists believe that TCD occurs only on walnut, butternut, and wingnut, but it is most damaging to native black walnuts, Juglans californica, J. hindsii, and J. nigra although the disease has been recorded on at least 10 species of walnuts or their hybrids in California. Often the first symptoms of TCD are flagging and yellowing leaves and branch dieback, Seybold said. Affected branches show sap staining and pinhole-sized beetle holes. Beneath the surface are dark stains caused by the fungus.

DAVIS--UC Davis undergraduate entomology researcher Jadrian Ejercito of the Shirley Luckhart lab won second place in the highly competitive student poster competition at the 99th annual meeting of the Pacific Branch of the Entomological Society of America (PBESA), held recently in Coeur d'Alene, Idaho. 

His poster, on a malaria mosquito, was titled “Effects of Abscisic Acid on the Lifespan and Fecundity of Anopheles stephensi.” Ejercito was the only UC Davis entomology student to win a poster award.

For the project, he collaborated with his mentor, Shirley Luckhart, a professor in the Department of Medical Microbiology and Immunity and co-director of the Center for Vectorborne Diseases; and doctoral candidate Elizabeth Glennon of the Luckhart lab.

Judges scored the poster on 12 criteria, including abstract, presentation, introduction, objectives, results and discussion, and significance of the results.

Ejercito, a senior scheduled to receive his bachelor's degree in entomology in June, works in the Luckhart main lab as well as the Contained Research Facility.

A graduate of Nathaniel A. Narbonne High School in Harbor City, Los Angeles County, Ejercito joined the Luckhart lab as a MURALS scholar, a program dedicated to supporting undergraduate researchers. MURALS is an acronym for “Mentorship for Undergraduate Research in Agriculture, Letters an Science.” Formed in the spring of 1988, under the sponsorship of the Office of Student Affairs and the academic leadership of the College of Letters and Science, MURALS now includes students from all academic disciplines. Its mission is to encourage students to further their education beyond the baccalaureate. 

Matt Daugherty

His seminar is from 12:10 to 1 p.m. in 122 Briggs Hall. Professor Jay Rosenheim is the host.

"Invasive arthropod vectors may threaten natural ecosystems, agriculture, or human health by promoting either new outbreaks of novel pathogens or more severe outbreaks of native pathogens," Daughtery, says in his abstract. "In California vineyards, the glassy-winged sharpshooter (Homalodisca vitripennis) is considered a major pest because it is a vector of Xylella fastidiosa, an endemic bacterial pathogen that causes Pierce's disease.

"I have been working to understand the mechanism by which this invasive vector is able to drive more severe disease outbreaks than are native sharpshooters. Experiments have included comparative tests of transmission efficiency among sharpshooter species, characterization of vector behavior with respect to host infection status, estimates of pathogen spread and the role of seasonality, and tests of the efficacy of vector control at limiting pathogen spread. Collectively, the results suggest that H. vitripennis is not inherently efficient at transmitting or spreading the pathogen relative to its native counterparts. Rather, this invader's ability to promote severe disease outbreaks likely stems from its ability to achieve high population densities in certain environments--an outcome that can be mitigated via biological and chemical control."

Daugherty received his bachelor's degree in biological sciences, with a minor in geology, in 1995 from UC Davis, and his master's degree in biological sciences in 2000 from Illinois State University. He earned his doctorate in integrative biology in 2006 from UC Berkeley. He served as a postdoctoral researcher at UC Berkeley's Department of Environmental Sciences, Policy & Management from 2006 to 2009 and then became a USDA postdoctoral fellow there in 2008-2009. Daughtery joined the faculty of UC Riverside's Department of Entomology in 2009.

Among his most recent publications: 

Zeilinger, A., and M.P. Daugherty 2014. Vector preference and host defense against infection interact to determine disease dynamics. Oikos 123:613-622.

Coletta-Filho, H., Daugherty, M.P., Ferreira, C., and J. Lopes. 2014. Temporal progression of Candidatus Liberibacter asiaticus infection in citrus and acquisition efficiency by Diaphorina citri. Phytopathology 104:416-421.

Rathé, A.A., Pilkington, L.J., Hoddle, M.S., Spohr, L.J., Daugherty, M.P., and G.M. Gurr 2014. Feeding and development of the glassy-winged sharpshooter, Homalodisca vitripennis, on Australian native plant species in the USA and implications for Australian biosecurity. PLoS One 9:e90410.

Rashed, A., Kwan, J., Baraff, B., Ling, D., Daugherty, M.P., Killiny, N., and R.P.P. Almeida 2013. Relative susceptibility of Vitis vinifera cultivars to vector-borne Xylella fastidiosa through time. PLoS One 8:e55326.

Gruber, B.R., and M.P. Daugherty 2013. Predicting the effects of seasonality on the risk of pathogen spread in vineyards: vector pressure, natural infectivity, and host recovery. Plant Pathology 62:194-204.

Rathé, A.A., Pilkington, L.J., Gurr, G.M., Hoddle, M.S., Daugherty, M.P., Constable F.E., Luck, J.E., Powell, K.S., Fletcher, M.J., and O.R. Edwards 2012. Incursion preparedness: anticipating the arrival of an economically important plant pathogen Xylella fastidiosa Wells (Proteobacteria: Xanthomonadaceae) and the insect vector Homalodisca vitripennis (Germar) (Hemiptera: Cicadellidae) in Australia. Australian Journal of Entomology 51:209-220.