Most people have never seen the walnut twig beetle, a tiny insect that spreads a fungal pathogen that kills walnut trees. 

No wonder. The insect, measuring about 1.5 millimeters long, is much smaller than a grain of rice. 

Now, however, they can see a teddy-bear-sized version, thanks to a University of California, Davis entomology major Kristina Tatiossian, a member of the Research Scholars Program in Insect Biology. 

Through the UC Davis Art/Science Fusion Program, Tatiossian, a junior, crafted a ceramic mosaic sculpture of the tiny walnut twig beetle for her research poster, “Flight Response of the Walnut Twig Beetle, Pityophthorus juglandis, to Aggregation Pheromones Produced by Low Densities of Males.”

The beetle jutting from the poster is so true to form that scientists studying the insect not only readily recognize it, but point out that it’s a female. That includes her mentor, chemical ecologist and forest entomologist Steve Seybold of the Davis-based Pacific Southwest Research Station, USDA Forest Service, and an affiliate of the UC Davis Department of Entomology.

Seybold and Andrew Graves, a former UC Davis researcher with the UC Davis Department of Plant Pathology, who now works for the USDA Forest Service, first detected the newly recognized beetle-fungus disease, known as Thousand Cankers Disease (TCD), in California in 2008. TCD had been detected earlier in Colorado and its impact had been noted even earlier in New Mexico, Oregon, and Utah.  TCD and its history are chronicled in a newly revised “Pest Alert” issued by the USDA Forest Service.

The beetle, emerging from a gallery of a black walnut tree, is accurate right down to the concentric ridges that occur on the skin (cuticle) that protects its head. Some observers claim the beetle is smiling and could be a cartoon character.

Tatiossian accomplished the research project as part of the  Research Scholars Program in Insect Biology, which aims to provide undergraduates with a closely mentored research experience in biology. Headed by professor Jay Rosenheim, and assistant professor Louie Yangof the UC Davis Department of Entomology, the program currently has 12 students; students apply when they are freshmen, sophomores or transfer students. Tatiossian joined the program in 2011 and is mentored by Steve Seybold. 


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Tatiossian completed the ceramic mosaic project over a four-week period. She earlier worked on two UC Davis Art/Science Fusion Program projects, including the “Tree of Life,” with the program’s founders, entomologist/artist Diane Ullman and artist Donna Billick. A former Los Angeles resident, Tatiossian will receive her bachelor’s degree in entomology this June and then plans to attend graduate school to study either biochemistry or virology.

Meanwhile, the poster is making the rounds. Tatiossian entered the poster in the Entomological Society of America’s student poster competition last year at its meeting in Knoxville, Tenn., where it drew lots of attention, not only for the research project but for the art.