RIVERSIDE, Calif. A catastrophic infestation of the goldspotted oak borer, which has killed more than 80,000 oak trees in San Diego County in the last decade, might be contained by controlling the movement of oak firewood from that region, according to researchers at the University of California, Riverside.
"This may be the biggest oak mortality event since the Pleistocene (12,000 years ago)," said Tom Scott, a natural resource specialist. "If we can keep firewood from moving out of the region, we may be able to stop one of the biggest invasive pests to reach California in a long time."
A cadre of UC researchers is leading the effort to assess and control the unprecedented infestation, in partnership with the U.S. Forest Service. Scott and others are working to identify where the infestation began, how it is spreading through southern California's oak woodlands, and what trees might be resistant. In October 2010 Scott and other UCR researchers received $635,000 of a $1.5 million grant of federal stimulus money awarded to study the goldspotted oak borer and sudden oak death.
The goldspotted oak borer (Agrilus auroguttatus), which is native to Arizona but not California, likely traveled across the desert in a load of infested firewood, possibly as early as the mid-1990s, Scott said. Researchers have confirmed the presence of the beetle as early as 2000 near the towns of Descanso and Guatay, where nearly every oak tree is infested.
The half-inch-long beetle attacks mature coast live oaks (Quercus agrifolia), California black oaks (Quercus kelloggii) and canyon live oaks (Quercus chrysolepis). Female beetles lay eggs in cracks and crevices of oak bark, and the larvae burrow into the cambium of the tree to feed, irreparably damaging the water- and food-conducting tissues and ultimately killing the tree. Adult beetles bore out through the bark, leaving a D-shaped hole when they exit.
Scott and Kevin Turner, goldspotted o
|Contact: Bettye Miller|
University of California - Riverside