Developing a Biological Control Program for the Invasive Goldspotted Oak Borer (Agrilus auroguttatus Schaeffer) in Southern California
The goldspotted oak borer, Agrilus auroguttatus Schaeffer, (Coleoptera: Buprestidae) is an invasive wood-boring beetle that aggressively attacks native oak trees in southern California, U.S.A. Native to Arizona, this beetle was initially detected in the Cleveland National Forest, San Diego County, California in 2004, but was likely introduced accidentally several years earlier through movement of infested oak firewood. Prior to its introduction and subsequent invasiveness in southern California, A. auroguttatus was rarely collected and very little information was known about this insect. The continuing ecological and economical damage caused by A. auroguttatus in southern California has made the development of a classical biological control program for this invasive pest a high priority. However, the implementation of an effective classical biological control program for any invasive species requires the knowledge of several critical components such as the pest's biology, area of origin, natural enemies (in the home and introduced range), and life history traits. Consequently, in order to acquire the basic information needed to initiate a classical biological control program for A. auroguttatus in California, this dissertation research had the following four objectives: 1) determine the fecundity and longevity of A. auroguttatus under varying diet and mating treatments, 2) assess the dispersal capabilities of A. auroguttatus adults in the laboratory using computerized flight mills, 3) use molecular methods to identify the area of origin for the California population of A. auroguttatus, and 4) survey for natural enemies of this beetle by deploying A. auroguttatus egg masses into the native and introduced range. Findings of this work showed that a carbohydrate-enriched diet increased longevity and fecundity, and the nutritional status and body size of A. auroguttatus adults had a significant influence on overall flight performance. The area of origin was not determined conclusively, although data suggests the Dragoon Mountains in Cochise Co., Arizona as a possible source for the California population of A. auroguttatus. Additionally, the first known egg parasitoid of A. auroguttatus was collected in AZ, and identified as Trichogramma sp. using molecular techniques. The results of this dissertation research will further the management of A. auroguttatus in southern California.