Dispersal of the emerald ash borer,Agrilus planipennis, in newly‐colonized sites

Abstract

AbstractEmerald ash borerAgrilus planipennisFairmaire (Coleoptera: Buprestidae) is an invasive forest insect pest threatening more than 8 billion ash (Fraxinusspp.) trees in North America. Development of effective survey methods and strategies to slow the spread ofA. planipennisrequires an understanding of dispersal, particularly in recently established satellite populations.We assessed the dispersal ofA. planipennisbeetles over a single generation at two sites by intensively sampling ash trees at known distances from infested ash logs, the point source of the infestations. Larval density was recorded from more than 100 trees at each site.Density ofA. planipennislarvae by distance for one site was fit to the Ricker function, inverse power function, and the negative exponential function using a maximum likelihood approach. The prediction of the best model, a negative exponential function, was compared with the results from both sites.The present study demonstrates that larval densities rapidly declined with distance, and that most larvae (88.9 and 90.3%) were on trees within 100 m of the emergence point of the adults at each site. The larval distribution pattern observed at both sites was adequately described by the negative exponential function.