A new pest is worrying California avocado growers. The Asian shot hole borer was first discovered in Los Angeles County in 2003 and has been causing quite the fuss as they have been shown to also affect avocado crops.
Last year, the insects appeared in avocado orchards in Ventura County. The UC Santa Barbara research team also detected them at many sites along the Santa Clara River. Now they've been spied in oak and sycamore trees in Montecito.
"Shot hole borers will bore into almost everything, including avocado trees, which is why they are getting a lot of attention," said graduate student Shelley Bennett, a member of UC Santa Barbara's Riparian InVasion Research Laboratory. "But these beetles also affect many native tree species."
While the bugs themselves are harmless, they can carry a pathogenic fungus that affects tree xylem, the vascular system that conducts water from the roots to the leaves. The fungus causes a disease called Fusarium dieback, which stops the flow of water and nutrients in at least 137 tree species.
The insects carry the fungus in special compartments called mycangia. Pregnant females bore through the bark and create galleries underneath, where they plant the fungus. If the tree is susceptible, the fungus grows and spreads. The females then lay eggs and, when they hatch, the larvae eat the fungus.
"The search is intensifying for biological solutions specific to this species and its biology," researcher Adam Lambert said. "The goal is to provide a cost-effective, environmentally compatible and permanent solution to the problem."
