Using molecular techniques to identify the source of the invasive gold-spotted oak borer, Agrilus coxalis Waterhouse (Coleoptera: Buprestidae)

The gold spotted oak borer (GSOB), a buprestid beetle native to oak forests of Southeastern Arizona, Central Mexico, and Northern Guatemala, is causing substantial injury and mortality of three oak species in southern California (>17,000 trees killed since 2002 and this number is increasing rapidly as GSOB populations build and this pest spreads). The integration of modern DNA-based techniques into the development of a classical biological control program can greatly enhance the efficacy of classical biological control by identifying the area of origin of the invasive population. Therefore, the use of these techniques increases the probability of pinpointing natural enemies that have evolved to exploit the genotype of the invading pest population. DNA extractions and molecular analyses were conducted from individuals collected in Arizona, Mexico, and California. DNA was extracted from individual specimens, then amplified and sequenced using polymerase chain reaction (PCR). The COI sequences of individuals from California, Arizona, and Mexico were used to construct a network of relationships among the sequences, providing an estimate of the relationships among those individuals and the potential source of the California invasion.