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Title: Optimizing ethanol-baited traps for monitoring damaging ambrosia beetles (Coleoptera: Curculionidae, Scolytinae) in ornamental nurseries

item Reding, Michael - Mike
item SCHULTZ, PETER - Virginia Polytechnic Institution & State University
item Ranger, Christopher
item OLIVER, JASON - Tennessee State University

Submitted to: Journal of Economic Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/23/2011
Publication Date: 12/20/2011
Citation: Reding, M.E., Schultz, P.B., Ranger, C.M., Oliver, J.B. 2011. Optimizing ethanol-baited traps for monitoring damaging ambrosia beetles (Coleoptera: Curculionidae, Scolytinae) in ornamental nurseries. Journal of Economic Entomology. 104:2017-2024.

Interpretive Summary: Ambrosia beetles are small insects that generally colonize (attack) physiologically stressed trees. Exotic ambrosia beetles tend attack trees that appear healthy and are causing significant economic damage to ornamental nursery trees in Midwestern, northeastern and southeastern states. Nursery growers try to protect trees by spraying insecticides before ambrosia beetles attack their trees. However, because of their small size it is difficult to determine when ambrosia beetles are active and thus it is difficult for growers to synchronize their sprays with beetle activity. As a result, the preventive sprays are often applied after the beetles have started attacking the nursery trees making the sprays ineffective. In many cropping systems, various types of traps have been used as early warning systems to detect insect pest activity. Previous research shows traps should be effective for monitoring activity of ambrosia beetles in nurseries. Bottle-style traps baited with ethanol are inexpensive and have been effective for capturing ambrosia beetles. However, further research is necessary to refine this technique and develop a reliable monitoring system for ambrosia beetles in nurseries. To that end, we tested bottle-traps with different amounts of ethanol (bait). We found that traps with 2 ethanol baits were more attractive and better able to detect early activity of ambrosia beetles than traps with 1 or no bait. Our results show that trapping can be used by growers as an effective early warning system and enable them to effectively synchronize their sprays with beetle activity.

Technical Abstract: The exotic ambrosia beetles Xylosandrus crassiusculus (Motschulsky) and Xylosandrus germanus (Blandford) are serious pests in ornamental tree nurseries. We tested different rates of commercially available pouch-style ethanol lures in bottle-traps to optimize bottle-traps as a monitoring system for use in nurseries. Trials were conducted in Ohio (2008 and 2009) and Virginia (2008), two states that have experienced significant damage from X. crassiusculus and/or X. germanus. There were 4 treatments: no-lure, 1-lure, 2-lure and 1+1-lure (1 lure in the trap and 1 suspended 0.5 m above the trap). Captures of X. crassiusculus and X. germanus were higher in all ethanol treatments than unbaited controls (no-lure), and were generally higher in treatments with two lures versus one. There was no difference between the 2-lure and 1+1-lure treatments. First detection of X. crassiusculus and X. germanus occurred more consistently in the treatments with two lures than one lure. Xyleborinus saxeseni (Ratzeburg), Anisandrus sayi Hopkins, Hypothenemus dissimilis Zimmermann and H. eruditus Westwood were also more attracted to traps baited with ethanol than unbaited controls. Xyleborinus saxeseni was captured in higher numbers in the treatments with two lures than one in Virginia but not Ohio. There was no difference in captures of the other species among ethanol treatments. The current research shows that ethanol release rates influence sensitivity of traps for detecting emergence of overwintered ambrosia beetles.