Attraction of ambrosia and bark beetles to coast live oaks infected by Phytophthora ramorum

Abstract

Sudden oak death, caused by Phytophthora ramorum (Werres, de Cock & Man in?t Veld), has killed thousands of oaks (Quercus spp.) in coastal California forests since the mid-1990s. Bark and ambrosia beetles that normally colonize dead or severely weakened trees selectively tunnel into the bleeding cankers that are the first visible symptoms to appear on infected coast live oaks, Q. agrifolia (Nee). The role of these beetles is of interest because once beetles attacked infected trees, median survival was found to decline, from seven to less than three years (McPherson and others 2005). Beetle attacks consistently precede the emergence of sporophores of Hypoxylon thouarsianum (Leveille) Lloyd, a decay fungus that structurally weakens infected trees. The dense clusters of ambrosia beetle tunnels can extend greater than 15 cm into the sapwood, impairing water conduction and potentially introducing opportunistic organisms. This research has three principal goals: 1. Quantify beetle responses to P. ramorum -infected coast live oaks; 2. Identify the factors that influence beetle attacks on these trees; 3. Evaluate the short nd long term effects of beetles on colonized trees.

Parent Publication

• Proceedings of the sudden oak death third science symposium

Citation

McPherson, Brice A.; Erbilgin, Nadir; Wood, David L.; Svihra, Pavel; Storer, Andrew J.; Standiford, Richard B. 2008. Attraction of ambrosia and bark beetles to coast live oaks infected by Phytophthora ramorum. In: Frankel, Susan J.; Kliejunas, John T.; Palmieri, Katharine M., tech. coords. 2008. Proceedings of the sudden oak death third science symposium. Gen. Tech. Rep. PSW-GTR-214. Albany, CA: U.S. Department of Agriculture, Forest Service, Pacific Southwest Research Station. pp. 173-175