Spatial spread and infestation risk assessment in the Asian longhorned beetle, Anoplophora glabripennis

The Asian longhorned beetle (ALB), Anoplophora glabripennis (Motschulsky) (Coleoptera: Cerambycidae), is recognised as potentially one of the most damaging invasive insects in Europe and North America. International trade has increased the risk of accidental introduction of ALB. An eradication programme was initiated in Northeast Italy in June 2009, when an ALB infestation was discovered. The infestation was monitored by annual surveys of all host-tree species growing in the eradication area. Infested trees were cut down and chipped. This study analyses the spatiotemporal distribution of infested trees for a 5-year period from 2008 to 2012 using a generalised linear model approach. The results show that spread and infestation risk were significantly affected by (1) distance of suitable hosts from the nearest infested trees, (2) number of infested trees in the surroundings, and (3) annual variation. The significant differences in beetle dispersal between years reflect to some extent the onset of the eradication programme. The model allowed the estimation of arbitrary probability-based management boundaries surrounding ALB-infested trees. For example, the model estimated a 0.1% probability of attack on a suitable host tree 1910m from an existing attack.