Diabrotica virgifera virgifera in Switzerland: future invasion trend into Germany via transalpine, terrestrial routes.

The western corn rootworm Diabrotica v.virgifera (D.v.v.) (Coleoptera:Chrysomelidae) is endemic to the New World. On at least 3 occasions, it invaded Europe (Miller et al. 2005). The first of these invasions took place in or before 1992 (Baca 1993) to Belgrade, Serbia, and gave rise to a rapidly expanding beetle population in SE Europe. Its larvae are causing economic damage to Zea mays for the last ten years, with increasing severity both in acreage and density. Meanwhile Germany is still without proven infestations as of 2005, but is surrounded by countries invaded by D.v.v. It will be a matter of time and careful search efforts with efficient traps to detect D.v.v. on German territory as well. Three main terrestrial routes of future introduction are likely (Wudtke et al. 2005, Hummel et al. 2005 a and b; Baufeld and Enzian, 2005), one of them leading from Northern Italy through Southern and Northern Switzerland to Southwestern and Southern Germany.