Co-occurrence of the invasive banded and European elm bark beetles (Coleoptera: Scolytidae) in North America

ABSTRACT The invasive European elm bark beetle, Scolytus multistriatus (Marsham), was detected in Massachusetts a century ago, and it now occurs throughout the continental United States and southern Canada. The Asian banded elm bark beetle, Scolytus schevyrewi Semenov, was discovered in the United States in 2003, and now occurs in 28 states and the province of Alberta, Canada. Although the indigenous populations of these two species are allopatric, the invasive populations are now sympatric in North America where they co-colonize elm (Ulmus spp.) trees. A large-scale survey of these two Scolytus species was conducted with baited funnel traps, Plexiglas panel traps, and Ulmus pumila L. trap logs. Sites (four per locality) were monitored around Sacramento, CA; Reno, NV; Ogden, UT; Newcastle, WY; and Fort Collins, CO (2006–2007), and Manhattan, KS, and Columbia, MO (both only in 2007). Trap catches of S. schevrewyi relative to both Scolytus species captured from all three trapping methods at each survey site...