Abstract
endo-Brevicomin, a pheromone component for tree-killing bark beetle Dendroctonus frontalis Zimmermann, the southern pine beetle, has a “peaked,” biphasic dose-response, being synergistic with attractants (pheromone component frontalin and host odors) at low release rates and attraction-reducing at high rates. Displacing an endo-brevicomin release device up to tens of meters from an attractant-releasing trap can increase synergistic effects. We investigated the interaction of endo-brevicomin device release rate and displacement. When one of a pair of 6 m distant, attractant-baited traps received an endo-brevicomin device varying in release rate across four orders of magnitude, catches in the endo-brevicomin amended and unamended traps peaked at the same, intermediate release of endo-brevicomin. However, catches were higher in the trap lacking endo-brevicomin at all but the lowest release rates, at which catches did not differ. When endo-brevicomin releasers were placed varying distances from an attractant-baited trap, tested release rates (0.45, 3.4, and 24 mg/d) enhanced catches at 4, 8, or 16 m distance, but, at 0 m, catch enhancement occurred only at the lowest rate and the highest rate produced catch reduction or no change. Our results indicate that endo-brevicomin releasers simultaneously produce long-range attraction-enhancing and short-range attraction-reducing effects for D. frontalis. These effects may promote switching of attack focus to adjacent hosts and propel growth of infestations. Our findings also indicate that maximum augmentation of trap catches should occur with the endo-brevicomin device displaced. Displacement short distances may preserve endo-brevicomin’s long-range attractive effects while lessening short-range inhibitory effects.
Keywords
Synergism · Biphasic · Dose-response · Trap · Displacement · Attraction
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Sullivan, B.T., Byers, J.A. & Brownie, C. Influence of Release Rate and Location of Release Devices of Pheromone Component endo-Brevicomin on Attraction of the Southern Pine Beetle. J Chem Ecol 51, 97 (2025). https://doi.org/10.1007/s10886-025-01653-8