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Influence of host volatiles as pheromone synergists for the southern and western pine beetle in Arizona Richard W. Hofstetter, Zhong Chen, Monica L. Gaylord, and Michael R. Wagner Northern Arizona University, Flagstaff, AZ 86011. Introduction
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Influence of host volatiles as pheromone synergists for the southern and western pine beetle in Arizona Richard W. Hofstetter, Zhong Chen,Monica L. Gaylord, and Michael R. Wagner Northern Arizona University, Flagstaff, AZ 86011 • Introduction • The current standard lure for the western pine beetle (Dendroctonus brevicomis) includes the host volatile myrcene as a pheromone-synergist. However, considerable geographic variation exists in monoterpene profiles among and between ponderosa pine populations which may influence the relative effectiveness of these lures. In Arizona, α-pinene is more abundant in pines than myrcene and we postulated it would be a better synergist to attract beetles. • The southern pine beetle (D. frontalis) is a common bark beetle pest in Arizona but little is known about the synergistic effects of monoterpenes as attractants in Ponderosa pine forests. • Objectives • Compare the effectiveness of commercially available lures and lures with modified host volatiles for D. brevicomis and D.frontalis. • Determine whether D. frontalis is more attracted to the western pine beetle lure than the southern pine beetle lure. • Results • The best lure to attract D. frontalis and D. brevicomis in Arizona was the combination of Frontalin, exo-brevicomin and α-pinene. • The replacement of myrcene with α-pinene attracted twice as many D. brevicomis and frontalis than the traditional lures. • D. frontalis appears to be significantly attracted to exo-brevicomin component in Arizona. The traditional D. frontalis lure (only frontalin or frontalin + terpene) was not very effective. • Temnochila was the most abundant predator trapped and was most attracted to lures containing exo-brevicomin. • Elacatis, a common predator in Arizona, was most attracted to the Frontalin, exo-brevicomin and α-pinene combination. For Elacatis, α-pinene appears to be an important component for attraction. Conclusions The chemical composition of hosts likely influences speciation and the evolution of aggregation pheromones in bark beetles. An explanation for the attraction of D. frontalis to the western pine beetle lure remains unclear. Preliminary studies show that D. frontalis are potentially attracted to the endo-brevicomin impurities (~3%) in the exo-brevicomin lure. Our results also indicate that predators use local terpenes to find potential prey. This is especially evident with the predator Elacatis. Materials and Methods Experimental design: Complete randomized block design with 10 replicate plots. Treatments: C: Control (no lure) F: Frontalin only FM: Frontalin + myrcene FP: Frontalin + α-pinene (-25% / +75%) FBM: Standard western pine beetle lure (Frontalin + exo-brevicomin + myrcene) FBP: Frontalin + exo-brevicomin + α-pinene BP: Exo-brevicomin + α-pinene (-25% / +75%) Lindgren funnel traps were baited with one of the seven treatments. Lures were from PheroTech and α-pinene (Sigma Aldrich) blend of -25% and +75% was mixed in the lab and placed into polypropylene vials. Release rates of pinene were 0.8 g /day. Acknowledgements: Support for this research was provided by USDA Forest Service, Western Bark Beetle Initiative, NAU School of Forestry, Centennial National Forest, and National Research Initiative of the USDA Cooperative State Research. Thanks to James Stewart, Gabe Degomez, Laine Smith, and Elisabeth Alden for assistance with field work and insect counting.