Tatiossian will will display the poster at in the Undergraduate Research Conference at UC Davison April 24 in Wellman Hall.  

By itself, the beetle, native to Arizona, California, New Mexico and Mexico, does little or no damage. But when coupled with the newly described fungus, Geosmithia morbida, it is killing thousands of walnut trees. 

The disease is creating havoc throughout much of the western United States, Seybold said, and is now heading east. Its primary host is the black walnut tree but it also attacks other walnut trees.

On her poster, Tatiossian explained that the walnut twig beetle (WTB), in association with the fungus, causes the newly recognized disease, Thousand Cankers Disease. WTB vectors the fungal pathogen, which infects phloem tissue around the beetle galleries, she wrote. “Numerous localized infections have led to the common name of the disease.”

“Male WTB initiate new galleries and produce an aggregation pheromone, which can be used to study patterns of initial host colonization behavior of WTB. It has been previously shown by Graves and colleagues (2010) that as the number of males in a branch is increased from 20 to 200, the flight response of males and females is similarly increased,” she wrote. “We investigated flight responses to lower numbers of males in cut branch sections of northern California black walnut, Juglans hindsii.”

Her objective: “To determine the minimum number of males in an artificially infested branch of Juglans hindsii necessary to elicit a flight response from WTB.”  She found that as little as one to five males is enough to elicit the aggregation response at her field study sites at two locations in Davis.

The poster will be displayed on the third floor of Briggs Hall, just outside the Department of Entomology’s administration office.

On her poster, Tatiossian credits Seybold; Extension entomologist Mary Louise Flint, associate director for Urban and Community IPM, UC Statewide Integrated Pest Program; entomology graduate student Stacy Hishinuma, and postdoctoral researcher Yigen Chen of the UC Davis Department of Entomology. And the UC Davis Art/Science Fusion Program where the tiny walnut twig beetle sprang to life.

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