Life history and trapping methods for the walnut twig beetle (Pityophthorus juglandis) in California

Abstract: The incidence of thousand cankers disease (TCD) in California is associated with increased activity of the walnut twig beetle (WTB), Pityophthorus juglandis Blackman, vector of the fungal causal agent Geosmithia morbida. In 2010 and 2011, we investigated the timing of WTB colonization and emergence, breeding behavior, and larval development and number of instars in a native northern California black walnut, Juglans hindsii, stand in Alameda County, California. At this site and other locations in northern California, we also developed and evaluated a pheromone-based WTB/TCD early detection system by optimizing the flight response of the beetle to various trap types, colors, and heights of placement.