Determining host susceptibility and implications for spread of invasive shot hole borers in riparian and agricultural ecosystems

Award Period
Award Amount
Agency Name
UC Agriculture And Natural Resources
Award Number
PI First Name
PI Last Name
Adam Lambert
Area/s of Research
Ecology and Evolution

A recently introduced cryptic complex of ambrosia beetles is of broad concern to agricultural interests and natural resource managers in southern California. Polyphagous (Euwallacea whitfordiodendrus) and Kuroshio (E. kuroshio) shot hole borers (SHB) are now present, and continue to spread, throughout coastal areas from San Diego to Santa Barbara and are rapidly expanding at our research and restoration sites along the Santa Clara River (Ventura County). The beetles carry obligate fungal symbionts that can cause severe dieback and mortality to susceptible host species. Hosts include important agricultural, riparian and urban tree species found in Ventura County. Characterization of shot hole borer infestations in riparian areas has been limited to detection surveys – research on SHB population dynamics, dispersal patterns and linkages to neighboring agricultural fields is necessary to develop management strategies for agricultural and natural resource protection. Our objective is to evaluate beetle-fungus-host tree dynamics by analyzing attack rates on trees, fungal growth rates and relative susceptibility of host tree species, and differences in tree anatomical and physiological characteristics that may facilitate fungal growth. Our results will provide critical information for determining host vulnerability to beetle and associated fungal attack.