Semiochemical-Mediated Flight Strategies of Two Invasive Elm Bark Beetles: A Potential Factor in Competitive Displacement

ABSTRACT A seven-state survey showed that the recently detected invasive Asian banded elm bark beetle, Scolytus schevyrewi Semenov, was abundant in areas of Colorado and Wyoming, whereas the long-established European elm bark beetle, S. multistriatus (Marsham), was not as abundant. In one of a series of studies to evaluate whether S. schevyrewi is competitively displacing S. multistriatus in their North American zone of sympatry, we characterized long-range flight responses infested or uninfested to small cut logs of American, Chinese, and Siberian elm, Ulmus americana, U. parvifolia, and U. pumila. Trials were conducted in Colorado and Wyoming to test the flight response of S. schevyrewi; in California to test the response of S. multistriatus; and in Nevada to test the responses of both species simultaneously. Studies with S. schevyrewi showed that males and females aggregated toward Ulmus spp. host volatiles but provided no evidence of a putative aggregation pheromone during the 0- to 48- or 48- to 96-h...