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ARS Home » Pacific West Area » Corvallis, Oregon » Horticultural Crops Research Unit » Research » Publications at this Location » Publication #235362
Title: Semiochemical-MediatedFlight Strategies of Two Invasive Elm Bark Beetles: A Potential Factor in Competitive Displacement

Author
item Lee, Jana
item HAMUD, SHAKEEB - USDA FOREST SERVICE
item NEGRON, JOSE - USDA FOREST SERVICE
item WITCOSKY, JEFF - USDA FOREST SERVICE
item SEYBOLD, STEVEN - USDA FOREST SERVICE

Submitted to: Environmental Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/15/2010
Publication Date: 4/1/2010
Citation: Lee, J.C., Hamud, S., Negron, J., Witcosky, J., Seybold, S. 2010. Semiochemical-mediated flight strategies of two invasive elm bark beetles: A potential factor in competitive displacement. Environmental Entomology. 39:642-652.

Interpretive Summary: We tested the flight attraction of the banded and European elm bark beetle, which are native to Asia and Europe, respectively. Both beetles are now overlapping in the United States, infesting the same elm trees. Determining the attractive and interruptive cues that affect these two species will help us to understand how these two species interact when sharing the same habitat. Field studies were conducted by hanging small cut elm logs that were clean or infested by beetles onto funnel-flight traps. Studies on the banded elm bark beetle were conducted in Colorado and Wyoming where it is abundant. This beetle showed no evidence of producing an aggregation pheromone and was strongly attracted to elm volatiles. Similar studies were conducted on the European elm bark beetle in California where it is abundant. These beetles were moderately attracted to elm volatiles and highly attracted to aggregation pheromones. Pheromone production was greater when females had infested an elm log for 48-96 hr compared to newly infested elm logs, 0-48 hr. Field studies were conducted in Nevada to determine the response of both species simultaneously to elms infested with their own or the other species. Banded elm bark beetles did not appear to differentiate between elms infested by: its own species, European elm bark beetles, or a mix of both species. The population of European elm bark beetles was too low to confidently determine their preferences.

Technical Abstract: A recent seven-state survey revealed that the newly invasive banded elm bark beetle, Scolytus schevyrewi, was abundant in areas of Colorado and Wyoming, USA, whereas the long-established European elm bark beetle, S. multistriatus was not as abundant. Behavioral trials were conducted by hanging small, freshly cut elm logs (bolts) with/without infestation by conspecifics around Cheyenne, Wyoming and Ft. Collins, Colorado to test the flight response of S. schevyrewi; around Sacramento, California to test the response of S. multistriatus; and elm bolts infested with both species around Reno, Nevada to test the responses of both species simultaneously. These studies compared the attraction of both beetle species to Siberian elm, Ulmus pumila, which is sympatric with S. schevyrewi’s native range, and to American elm, U. americana, which is an adventive host in the United States. Studies with S. schevyrewi revealed that males and females aggregated towards host volatiles, but provided no evidence of response to a putative pheromone during the 0-48 or 48-96 hr period of infestation. In contrast, in reciprocal studies Scolytus multistriatus were attracted to Ulmus spp. over unbaited controls, more to U. pumila infested with conspecifics than without, and more during the 48-96 hr versus 0-48 hr period of infestation. Results confirmed that S. multistriatus males and females aggregated towards host elm volatiles and that females produced an aggregation pheromone. In a cross-attraction study, S. schevyrewi displayed neither flight preference nor interruption to U. pumila infested with conspecifics, heterospecifics, or a mix of both species. Flight response of S. multistriatus was too low in the cross-attraction study to draw conclusions. Although S. multistriatus aggregates moderately to host volatiles and strongly to pheromones emitted after a few days, S. multistriatus may have a relative disadvantage by colonizing elm hosts more slowly than S. schevyrewi, which aggregates very strongly to host volatiles.