The Authors 



Research Summary 



Barbara J. Bentz is a Research Entomologist with the 

 intermountain Research Station's Mountain Pine Beetle 

 Project, and Assistant Professor (Federal Cooperator) in 

 the Forest Resources Department at Utah State Univer- 

 sity. She received a Ph.D. degree from Virginia Polytech- 

 nic Institute and State University in 1991 and an M.S. 

 degree from the University of Idaho in 1984. 



James A. Powell is an Assistant Professor in the Math- 

 ematics Department at Utah State University. He re- 

 ceived a Ph.D. degree in applied mathematics from the 

 University of Arizona in 1990. 



Jesse A. Logan is Project Leader for the Intermountain 

 Research Station's Mountain Pine Beetle Project. He is 

 also a Professor in the Forest Resources Department at 

 Utah State University and Acting Director for the Center 

 for Research on Disturbance Ecology, a joint venture 

 between the Intermountain Station and Utah State Uni- 

 versity. He holds a Ph.D. degree in entomology from 

 Washington State University, an M.S. degree in entomol- 

 ogy from Colorado State University, and a B.S. degree in 

 biology from Colorado State University. 



Colonization of a host tree by the mountain pine beetle 

 involves a complex, synergistic interaction between host- 

 produced chemicals and beetle-produced pheromones. 

 This system of chemical communication enables a mas- 

 sive aggregation of beetles on a single resource, thereby 

 ensuring host death and subsequent beetle population 

 survival. Because a single host tree is a limited food and 

 breeding resource, mountain pine beetle populations 

 have evolved a mechanism for termination of colonization 

 on a tree at optimal beetle densities, with a concomitant 

 switch of attacks to nearby trees. Several hypotheses 

 attempt to explain this pheromone-mediated phenomenon. 

 In an effort to more fully understand the entire coloniza- 

 tion process, we observed the daily spatial and temporal 

 attack process of mountain pine beetles (nonepidemic) 

 attacking lodgepole pine. Results from this preliminary 

 study suggest that beetles switch attacks to a new host 

 tree before the original focus tree is fully colonized, and 

 that verbenone, an antiaggregating pheromone, may be 

 acting within a tree rather than between trees. 



Acknowledgments 



The authors thank Ken Gibson, Dan Miller, and Ken Raffa 

 for helpful reviews of the manuscript, and Bridget Kobe 

 for technical assistance in the field. 



The use of trade or firm names in thiis publication is for reader information and does not 

 imply endorsement by the U.S. Department of Agriculture of any product or sen/ice. 



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