Developing Monitoring Techniques for the Invasive Goldspotted Oak Borer (Coleoptera: Buprestidae) in California

Tom W. Coleman, Yigen Chen, Andrew D. Graves, Stacy M. Hishinuma, Nancy E. Grulke, Mary Louise Flint, Steven J. Seybold
2014 Environmental Entomology  
The goldspotted oak borer, Agrilus auroguttatus Schaeffer (Coleoptera: Buprestidae), is an invasive species that has colonized oak woodlands in southern California. To better deÞne its seasonal ßight activity, assist with forest and integrated pest management activities, and deÞne the current distribution in California, an effective monitoring technique for A. auroguttatus is necessary. We assessed the efÞcacy of two colors of ßight-intercept prism traps, the placement of these traps at three
more » ... ights, and several commercially available lures [Manuka oil, Phoebe oil, and a green leaf volatile, (3Z)-hexenol] for monitoring the ßight of adult A. auroguttatus. Landing rates and the densities of D-shaped emergence holes of A. auroguttatus adults were assessed on the lower stems of coast live oak, Quercus agrifolia Ne ´e, of varying size and crown health classes. Purple ßight-intercept prism traps placed at heights of 3 m and 4.5 m caught signiÞcantly more female A. auroguttatus than green prism traps. In one experiment, males also responded at a signiÞcantly higher level to purple than to green prism traps placed at 3 m height. The addition of commercially available lures signiÞcantly enhanced male, but not female, A. auroguttatus trap catch when compared with unbaited control traps. There were no differences among male ßight responses to the three lures. A. auroguttatus landing rates and emergence hole densities were signiÞcantly greater on the largest-diameter trees (>76.2 cm diameter at breast height) and on trees with severe crown thinning or complete crown collapse. The annual increment in emergence hole densities was also signiÞcantly greater on trees with severe crown thinning or complete crown collapse. In three trapping studies over multiple years in southern California, the adult ßight period began as early as mid-May, peaked in mid-June to early July, and ended in early-to mid-September. To demonstrate the efÞcacy of the detection method for A. auroguttatus (unbaited purple traps at 3 m height), a delimitation survey conducted from 2009 to 2012 conÞrmed that the species was only present in San Diego Co., but that the distribution was expanding northward. KEY WORDS Agrilus auroguttatus, ßight-intercept prism trap, oak mortality, phloem/wood borer, semiochemical The invasive goldspotted oak borer, Agrilus aurogut tatus Schaeffer (Coleoptera: Buprestidae), is a re cently recognized threat to forest health in southern California (Coleman and Seybold 2008 a,b). From 2002 to 2013, A. auroguttatus has caused elevated levels of tree mortality, killing nearly 25,000 oaks within an area of 212,784 ha in San Diego Co.
doi:10.1603/en13162 pmid:24755194 fatcat:hfezoud6avhl7ok6bkd6biofhq