Posts Tagged: Steve Seybold
Chemical ecologist and forest entomologist of Steve Seybold of the USDA Forest Service, Pacific Southwest Research Station, Davis, Calif., and a faculty affiliate of the UC Davis Department of Entomology, is leading a research group to characterize the disease in California.
A new member of the team is UC Davis entomology graduate student Stacy Hishinuma (right), who just received a McBeth Memorial Scholarship to help fund her research.
TCD is caused by the walnut twig beetle, Pityopthorus juglandis, in association with a newly described fungus, Geosmithia morbida.
“The beetle is believed to be native to Arizona, California, New Mexico and Mexico,” Hishinuma said, “but was never associated with walnut tree mortality until just recently.”
The disease was first noticed in canker-riddled black walnuts in Utah and Oregon in the early 1990s, but scientists attributed that to environmental stress. 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. TCD is now found in eight western states (Arizona, California, Colorado, Idaho, New Mexico, Oregon, Utah and Washington), plus Tennessee.
“My project focuses on understanding more about the biology of the beetle and fungus and documenting the frequency and progression of TCD in various walnut species throughout California,” Hishinuma said. “The McBeth scholarship is funding my travel to field sites across California.”
Hishinuma, who is seeking her master’s degree in entomology, works with major professor and integrated pest management (IPM) specialist Mary Lou Flint and is co-advised by Seybold. Flint, with the statewide UC IPM Program, is the associate director for urban and community IPM, and a Department of Entomology extension specialist.
The fungus enters the tree when the beetle tunnels into the bark to prepare egg galleries. “The fungus is probably carried as conidia on the beetle’s elytra or wing covers,” said Seybold, who has been studying the chemical ecology and behavior of bark beetles for more than 25 years.
Scientists believe that TCD occurs only on walnut, predominantly native black walnut, Juglans californica and J. hindsii, although the disease has been recorded on 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.
A tree can survive the stress produced by a few cankers, but when high populations of the beetle enter the tree and the numerous small cankers coalesce, the disease girdles twigs and branches. Eventually TCD attacks the main stem of the weakened tree down to the soil line.
Last summer, a USDA/UC Davis research team began tracking the pathogen and the beetle throughout the state, particularly in commercial orchards.
To prevent spread, infected trees should be removed and destroyed immediately by grinding or burning to ensure that beetles are destroyed, Seybold said. Infested walnut for chips, firewood, or woodworking should not be moved to new areas. Possible detections can be reported to the local agricultural commissioner’s office or to the local UC Cooperative Extension office.
Hishinuma, from Burbank, completed her undergraduate work at UC Davis in animal biology, with an entomology emphasis. She began her graduate studies this fall after working for a year in southern California assisting with research on the goldspotted oak borer, a relatively new pest in southern California that kills oak trees. Beetle-infested firewood contributes to the problem, as it does with thousand cankers disease.
The McBeth Memorial Scholarship was established in 1986 by Barbara McBeth Woodruff (1924-2007) in honor of her parents, Ira Guy McBeth and Rose McBeth, and her sister Frances McBeth Black. Ira Guy McBeth, an entomologist who received his doctorate from the University of California in 1915, made notable contributions to the citrus industry and served as an executive in agricultural, chemical and development companies.
Meanwhile, a thousand questions about thousand cankers disease...and maybe soon...solutions.
Steve Seybold discussed thousand cankers disease in a seminar presented May 19, 2010 to the UC Davis Department of Entomology. The seminar was webcast and is archived on the entomology website. (USDA Forest Service Pest Alert on Thousand Cankers Disease of Walnut (targeting eastern U.S. region). (May 2010)
UC IPM website (Authors: Andrew Graves, postdoctoral researcher, formerly with the UC Davis Department of Plant Pathology; Mary Louise Flint, UC IPM Program and Department of Entomology, UC Davis; Tom Coleman, USDA Forest Service, Forest Health Protection, San Bernardino; and Steven Seybold, USDA Forest Service, Pacific Southwest Research Station, Davis)
Detected in Tennessee (News release, Aug. 9, 2010, UC Davis Department of Entomology website)
Detected in California (News release, July 2, 2010, UC Davis Department of Entomology website)
Dying Walnut Trees in Davis
Walnut Twig Beetle
That quote sound familiar? Chemical ecologist Jacques Le Magnen (1916-2002) said that back in 1970.
World-renowned organic chemist Wittko Francke (right) of the University of Hamburg, Germany, called attention to Le Magnen's quote at a UC Davis Department of Entomology seminar on Wednesday noon, Dec. 8.
It bears repeating: "Nature is more a world of scents than a source of noise."
Insects communicate in a chemical language or chemical signals, Francke told the crowd.
Indeed, scientists have long known that methods that can attract or repel insects have important applications for agricultural pests and medical entomology.
Francke told how a queen bee secretes compounds that regulate development and behavior of the colony, and how an orchid releases the scent of a female wasp to attract male wasps— a scent that results in pollination. He also touched on the “calling cards” of a number of other insects, including bumble bees, wasps, pea gall midges, stingless bees, bark beetles and leafminers. He pointed out that that plants, too, send chemical signals.
UC Davis graduate students James Harwood and Amy Morice of the James R. Carey lab video-taped the seminar. It will be online soon at http://entomology.ucdavis.edu/news/webcastlinks.html
Francke was introduced by chemical ecologist-forest entomologist (and UC Davis Department of Entomology affiliate) Steve Seybold of the USDA Forest Service, Pacific Southwest Research Station, Davis.
No stranger to UC Davis, Francke previously collaborated with chemical ecologist Walter Leal, professor and former chair of the UC Davis Department of Entomology, on attractants for navel orangeworm.
In his talk, Francke mentioned Leal’s discovery of a sophisticated mechanism for the isolation of the chemical communication channels of two species of scarab beetles.
Seybold and Francke are collaborating on the chemical signals of the walnut twig beetle, which in association with a newly described fungus, causes thousand cankers disease, a killer of walnut trees.
Thousand cankers disease (TCD) is now found in seven western states, plus Tennessee. Seybold is a key researcher in California.
Scientists believe that TCD occurs only on walnut, predominantly native black walnut, Juglans californica and J. hindsii, although the disease has been recorded on 10 species of walnuts or their hybrids in California.
Often the first symptoms of TCD are flagging and yellowing leaves and branch dieback, said Seybold, who has been studying the chemical ecology and behavior of bark beetles for more than 25 years. Affected branches show sap staining and pinhole-sized beetle holes. Beneath the surface are dark stains caused by the fungus.
A USDA/UC Davis research team is tracking the pathogen and the beetle throughout California, particularly in commercial orchards.
That all points back to “Nature is more a world of scents than a source of noise.”
They Deal with Scents
Remember the exciting news article published in November of 2009 in Science Daily about how an orchid species on the Chinese island of Hainan "fools its hornet pollinator by issuing a chemical that honey bees use to send an alarm?"
The research was first published in Current Biology, a Cell Press publication.
"The discovery explains why the hornets, which capture honey bees to serve as food for their larvae, have been observed to literally pounce on the rewardless Dendrobium sinense flowers," the Science Daily author wrote.
Can you imagine? Hornets "detect" one of their favorite foods--honey bees--and they pounce on the flower and come up empty-handed or "empty-mouthed?"
The orchids produce a deceptive chemical, a compound called Z-11-eicosen-1-ol, described as "a rarity even in the insect world."
One of the researchers involved in this study--and hundreds of other insect communication studies--is world-renowned chemical ecologist Wittko Francke (top photo) of the University of Hamburg, Germany.
And now he's coming to the University of California, Davis, to present a seminar.
Francke will speak on "Insect Semiochemicals: Structural Principles and Evolution" at a UC Davis Department of Entomology seminar on Wednesday, Dec. 8 from 12:10 to 1 p.m. in 122 Briggs Hall, off Kleiber Hall Drive. He'll be introduced by host and fellow chemical ecologist Steve Seybold of the USDA Forest Service, Pacific Southwest Research Station, Davis, and an affiliate of the UC Davis Department of Entomology."Professor Francke has been a driving force in the field of chemical ecology for the last four decades, discovering countless new natural product chemicals of behavioral significance for animals and helping us to understand how plants and animals interact," said Seybold (left).
"Nearly everyone in the field has collaborated with him at some level; he has been a consummate mentor to younger chemical ecologists and has always been generous with his time, intellect, and chemical skills to everyone in that community," Seybold said. "He is remarkably brilliant in that he sees patterns in the make-up and synthesis of bio-organic compounds that most biologists, and even many chemists, may overlook."
And also barbecued marinated ball tip and chicken quarters with barbecued beans and salad.
You can't ask for anything better than that! Bugs on the agenda and ball tip on the plates! (Well, salad, too!)
The occasion: the last Nor Cal meeting of the year. The members and their guests will meet from 9:15 a.m. to 2:30 in the Contra Costa Mosquito and Vector Control District, 155 Mason Circle, Concord.
One of the hot topics is a newly discovered disease that kills black walnut trees.
Research entomologist Steve Seybold (above) of the Pacific Southwest Research Station, USDA Forest Service, Davis, and an affiliate of the Department of Entomology, University of California, Davis, will provide an update on the disease at 10:15 a.m. Caused by a newly described fungus (Geosmithia morbida) spread by the tiny walnut twig beetle (Pityophthorus juglandis), it is known as "thousand cankers disease."
The disease is becoming a "significant problem" in California and seven other western states and could very well spread throughout the United States. It was detected in Tennessee last summer.
The society's agenda:
Registration for club members and guests, with coffee
“Bedding Plant/Container Color Alliance in California,” Christine Casey, UC Davis
“Thousand Cankers Disease” by Steve Seybold of the USDA Forest Service and an affiliate of the UC Davis Department of Entomology
“Statewide Invasive Insect and Mite Activities, 2009-2010, by Kevin Hoffman, Pest Detection and Emergency Projects, California Department of Food and Agriculture
Annual business meeting; election of officers
Catered lunch by Kinder’s Custom Meats (barbecued marinated ball tip and chicken quarters with barbecued beans, tossed green salad, potato and fresh fruit salads, assorted soft drinks and cookie for $15)
“UC Berkeley Drywood Termite Inspection Research Update” by Robin Tabuchi of UC Berkeley
“Oriental Fruit Moth Parasitoid" by UC Integrated Pest Management (UC IPM) Program Advisor Walter Bentley, UC Kearney Agricultural Center, Pariier
The Northern California Entomology Society meets three times a year: the first Thursday in February in Sacramento; the first Thursday in May, at UC Davis; and the first Thursday in November in Concord. Membership is open to the public; dues are $10 year. The president is agricultural biologist Matthew Slattengren of the Contra Costa County Department of Agriculture.
Extension apiculturist Eric Mussen of the UC Davis Department of Entomology faculty serves as the secretary-treasurer and is taking reservations for the luncheon. He may be reached at email@example.com or call (530) 752-0472.
The society is comprised of university faculty, researchers, pest abatement professionals, students and other interested persons.
The officers are hoping to build up membership in the organization, so if you have a keen interest in bugs--or what's bugging California--sign up!
Walnut Twig Beetle
Thousand cankers disease, which infects and kills black walnut trees, has spread from the western United States to the eastern United States.
Officials announced Aug. 5 that the disease has been detected in Knox County in east Tennessee. This marks the first detection of the disease east of the Mississippi River.
Previously, the disease was known to eight western states: Arizona, California, New Mexico, Colorado, Idaho, Oregon, Utah and Washington.
And now, Tennessee. It's probably in other states across the Great Plains and east of the Mississippi River, as well.
The disease, caused by the walnut twig beetle (Pityophthorus juglandis) in association with a newly described fungus with the proposed name of Geosmithia morbida), occurs only on walnut species. Eastern black walnut is one of the most susceptible species.
By itself, the walnut twig beetle doesn't present a major problem. Together they wreak havoc.
A pest alert, distributed by the U.S. Forest Service and co-authored by Davis-based researcher Steve Seybold, is sounding the alarm
Seybold, research entomologist with the U.S. Forest Service, Pacific Southwest Research Station, Davis, and a faculty affiliate of the UC Davis Department of Entomology, says the disease symptoms to watch for are branch mortality; numerous small cankers on branches and the main stem of the tree; and the entry and exit holes of the tiny bark beetles. (See news article on presence of the disease in Davis.)
In an attempt to stop the spreading of the disease, the Tennessee Department of Agriculture (TDA) plans to quarantine Knox County to prohibit the movement of firewood and black walnut nursery stock and to limit the movement of black walnut timberland.
The TDA's Division of Forestry estimates that the state has 26 million black walnut trees (both on public and private land). They are valued as high as $1.47 billion.
That's "billion" with a "B."
The losses would be more than monetary, though.
We received a telephone call from a Washington state resident today who is worried--and rightfully so--that his two 100-year-old majestic black walnut trees might contract the disease.
And to think that they could be felled by this duo: a fungus hitching a ride on a tiny walnut twig beetle boring into a tree.
It's a beetle that's smaller than a grain of rice.
Walnut Twig Beetle