Visual, Acoustic, and Volatile Cues to Improve Performance of Trapping Ambrosia Beetles (Coleoptera: Curculionidae)
Type of Degreethesis
Entomology and Plant Pathology
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Three widely distributed species of ambrosia beetles (Coleoptera: Curculionidae: Scolytinae), Xylosandrus germanus Blandford, Xylosandrus crassiusculus Motschulsky, and Cnestus mutilatus Blandford are introduced pests that cause damage to various tree cultivars by engraving tunnel networks and inoculating trees with their symbiotic fungi and secondary pathogens. Populations of these species have established in several regions of the United States. After a series of field experiments investigating the influence of visual and volatile cues and their capability to attract Scolytinae, it was demonstrated that trap captures can be influenced by the availability of specific nanometer wavelengths of light as well as chemical cue pairing. Different attractant cues were evaluated such as ratios of ethanol to methanol (0:100, 25:75, 50:50, 75:25, 100:0), conophthorin, and various LED color wavelengths: 395 nm (UV), 470 nm (blue), 525 nm (green), 625 nm (red). Visual cues and their role in orientation were also assessed in field experiments, showing the importance of peak diurnal flight activity occurring between 16:00 and 18:00 hours. Using Cnestus mutilatus as a model species, the acoustic sound produced by walking was characterized in laboratory experiments. These demonstrated that it is possible to isolate the unique signal derived from walking by an ambrosia beetle, which could be used for species detection in traps deployed in ornamental nurseries. This research suggests that X. germanus, X. crassiusculus, C. mutilatus, and other Scolytinae have species-specific attractant cue specifications and acoustic production, both of which can be used to further understand and manage these organisms. By integrating some of these concepts, it could lead to better trapping efficiency to improve the timing of insecticide applications. An extensive analysis looking at the physiological mechanisms underlying attractant cue specifications and acoustic production could further our understanding of ambrosia beetles.