Richard Hofstetter, Ph.D. - Associate Professor

hofstetter Research Interests

Community Ecology, Population Dynamics, Tritrophic Interactions, Symbioses and Insect Acoustics.

Our current research involves understanding the response of insects to forest management through thinning and wildfire in pine forests, effects of tree characteristics and resin defense against insects, the role of bark beetles in influencing the structure and evolution of pine forest ecosystems, improving insect attractants, the effects of thinning piles on forest insect communities, interactions among fungi, mites and bark beetles across multiple bark beetle communities, and the evolution and ecology of acoustic communication in bark beetles. The National Science Foundation, USDA Competitive Grants Program, and USDA Forest Service support this research.

Bark beetles are integral components in forest ecosystems and can be viewed as beneficial or detrimental depending on the management objectives. Most bark beetles cause little or no economic damage as they normally infest branches, stumps, and stems of standing dead, severely weakened trees or downed material. Although all bark beetles are relatively small, 1mm to 8mm in length, several species attack and kill living, apparently healthy trees. In the southwest United States there are several important beetle species in the genus Ips and Dendroctonus that attack and kill large stands of conifers (

In Arizona, there are currently 30 known species of bark beetle that inhabit the Ponderosa pine. This complex of bark beetles offers an interesting community of study that is rarely found anywhere else in the world. There are many interesting questions, both applied and basic, that can be asked: How do we manage our forest to account for multiple beetle species and their pathogens? How does interspecific competition between species affect beetle population dynamics? Why do particular beetle species outbreak while others do not? Are fungi and mites associated with bark beetles switching among beetles hosts?


B.S. University of Wisconsin, Madison, 1992
M.S. University of Wisconsin, Madison, 1996
Ph.D. Dartmouth College, 2003
Postdoctoral: Dartmouth College 2004

Present Appointment

Associate Professor of Forest Entomology. School of Forestry, NAU        2011-present

Appointment History at NAU

Assistant Professor of Forest Entomology. School of Forestry, NAU        2008 - 2011
Assistant Professor-Research. School of Forestry, NAU                          2005 - 2008

Contact Information

Office: Building 82 - Room 208
Phone: 928.523.6452

Selected Publications

Mercado, J., R.W. Hofstetter and D. Reboletti. 2014. Ectobionts (external fauna) associated with the mountain pine beetle. Journal of Forest Science (accepted January 2014)

Aflitto, N. and R.W. Hofstetter. 2014. Use of acoustics to deter bark beetles from entering trees. Pest Management Science (DOI: 10.1002/ps.3720)

Smith, L., R. Hofstetter, and R. Mathiasen. 2014. Insect communities associated with Douglas-fir dwarf mistletoe witches’ brooms in Northern Arizona. The Southwestern Naturalist 58(4).

Foelker, C.J. and R.W. Hofstetter. 2014. Heritability, fecundity and sexual size dimorphism in four species of bark beetles (Coleoptera: Curculionidae: Scolytinae). Annals of the Entomology Society of America 107: 143-151.

Davis, T.S. and R.W. Hofstetter. 2014. Allometry of phloem thickness and resin flow and their relation to tree chemotype in a southwestern ponderosa pine forest. Journal of Forest Science 60 (

Hofstetter, R.W. and J.C. Moser. 2014. Role of mites in insect-fungus associations. Annual Review of Entomology 59 (1): 537-557.

Hofstetter, R.W., D.D. Dunn, R. McGuire, and K.A. Potter.  2014. Using acoustic technology to reduce bark beetle reproduction. Pest Management Science 70(1): 24-27.

Miller, D.R., K.J. Dodds, A.Y. Eglitis, C.J. Fettig, R.W. Hofstetter, D.W. Langor, A.E. Mayfield III, A.S. Munson, T.M. Poland and K.F. Raffa. 2013. Trap Lure Blend of Pine Volatiles and Bark Beetle Pheromones for Monochamus spp. (Coleoptera: Cerambycidae) in Pine Forests of Canada and the United States. Journal of Economic Entomology 106: 1684-1692.

Davis, T.S., T.L. Crippen, R.W. Hofstetter, and J.K. Tomberlin. 2013. Microbial volatile emissions as arthropod semiochemicals. Journal of Chemical Ecology 39: 840-859.

Hofstetter, R.W., J.C. Moser, and S. Blomquist.  2013. Chapter 14: Mites associated with bark beetles and their hypophoretic Ophiostomatoid fungi. In The Ophiostomatoid Fungi: Expanding Frontiers (Wingfield & Seifert, eds.). CBS-KNAW Fungal Biodiversity Centre, Utrecht, The Netherlands. Pages 165-176.

Yturralde, K.M. and R.W. Hofstetter. 2012. Efficacy of commercially available ultrasonic pest repellent devices to affect behavior of bed bugs, Cimex lectularius. Journal of Economic Entomology 105(6): 2107-2114.

Cardoza, Y. J., R. W. Hofstetter, and F. E. Vega. 2012. Insect-associated microorganisms and their possible role in outbreaks. In "Insect Outbreaks Revisited" (P. Barbosa, D. K. Letourneau, and A. A. Agrawal, Eds.), pp. 155-174. Wiley-Blackwell, UK.

Davis, T.S. and R.W. Hofstetter. 2012. Plant secondary chemistry mediates the performance of a nutritional symbiont associated with a tree-killing herbivore. Ecology 93(2): 421-429.

Hofstetter, R.W., M.L. Gaylord, S. Martinson and M. Wagner. 2012. Attraction to monoterpenes and beetle-produced compounds by syntopic Ips and Dendroctonus bark beetles and their predators. Agriculture and Forest Entomology 14: 207-215.

Davis, T., K. Jarvis, K. Parise and R. Hofstetter. 2011. Oleoresin exudation rate increases and viscosity declines following a fire event in a ponderosa pine ecosystem.  Journal of the Arizona-Nevada Academy of Science 43(1): 6-11.

Davis, T.S. and R.W. Hofstetter. 2011. Oleoresin chemistry mediates oviposition behavior and fecundity of a tree-killing bark beetle. Journal of Chemical Ecology 37: 1177-1183.

Smith, L., R. Mathiasen and R. Hofstetter. 2011. Biomass of witches’ brooms caused by Douglas-fir mistletoe in northern Arizona. Journal of the Arizona-Nevada Academy of Science 43(1): 40-47.

Evans, L.M., R.W. Hofstetter, M.P. Ayres and K.D. Klepzig. 2011. Temperature changes a community: Dendroctonus frontalis and its symbionts. Environmental Entomology 40(4): 824-834.

Hofstetter, R.W. 2011.Chapter 11: Mutualists and Phoronts of the Southern Pine Beetle.  In Southern Pine Beetle II (K.D. Klepzig & R. Coulson, eds.). United States Dept. of Agriculture Forest Service, Southern Research Station General Technical Report SRS-140. Pages 161-181.

Klepzig, K.D. & R.W. Hofstetter. 2011. Chapter 9: From Attack to Emergence: Interactions between southern pine beetle, mites, microbes and trees.  In Southern Pine Beetle II (K.D. Klepzig & R. Coulson, eds.). United States Dept. of Agriculture Forest Service, Southern Research Station General Technical Report SRS-140. Pages 141-152.

Davis, T.S. and R.W. Hofstetter. 2011. Reciprocal interactions between the bark-beetle associated yeast Ogataea pini and host plant phytochemistry.  Mycologia 103(6): 1201-1207.

Hofstetter, R.W. and M.R. Wagner. 2011. Carbon, bark beetles and biofuel. Journal of Forestry 109: 245-246.

Gaylord, M.L., R.W. Hofstetter, T.E. Kolb and M.R. Wagner. 2011. Limited response of ponderosa pine bole defenses to wounding and fungi. Tree Physiology 31: 428-437.

Davis, T.S., R.W. Hofstetter, J.T. Foster, N.E. Foote and P. Keim. 2011. Interactions between the yeast Ogataea pini and filamentous fungi associated with the western pine beetle. Microbial Ecology 61: 626-634.

Hulcr, J., A.S. Adams, K.F. Raffa, R.W. Hofstetter, K.D. Klepzig, and C.R. Currie. 2011. Presence and diversity of Streptomyces in Dendroctonus and sympatric bark beetle galleries across North America. Microbial Ecology 61: 759-768

Fierke, M.K., D. Nowak, and R.W. Hofstetter. 2011. Chapter 9: Forest Health Monitoring. In Using the Baseline Mortality Concept in Forest Health (eds. John Castello and Steve Teale). SUNY College of Environmental Science and Forestry. Cambridge University Press.

Davis, T.S., R.W. Hofstetter, K.D. Klepzig, J.T. Foster, and P. Keim. 2010. Sympatry and allopatry of beetle hosts influences the competitive interactions among fungal mutualists. Journal of Yeast and Fungal Research 1: 118-126.

Gaylord, M, L., R.W. Hofstetter, and M.R. Wagner. 2010. Impacts of silvicultural thinning treatments on bark beetle trap captures and tree attacks during low bark beetle populations in ponderosa pine forests of northern Arizona. Journal of Economic Entomology 103(5): 1693-1703.

Fischer, M., K. Waring, R. Hofstetter & T. Kolb. 2010. Characteristics of ponderosa pine susceptible to Dendroctonus adjunctus. Forest Science 56: 473-483.

Waring, K.M., D.M. Reboletti, L.A. Mork, C.H. Huang, R.W. Hofstetter, A.M. Garcia, P.Z. Fule, and T.S. Davis. 2009. Modeling the impacts of two bark beetle species under a warming climate in the southwestern USA: Ecological and economic consequences. Environ. Management 44: 824-835.

Davis, T.S. and R.W. Hofstetter. 2009. The effects of gallery density and ratio on the fitness and fecundity of two sympatric bark beetles. Environmental Entomology 38(3): 639-650.

Hofstetter, R.W., J.C. Moser, and R. McGuire. 2009. Observations of the mite Schizosthetus lyriformis (Acari: Parasitidae) preying on bark beetle eggs and larvae. Entomological News 120(4): 397-400.

Raffa, K.F., B. Aukema, B.J. Bentz, A. Carroll, N. Erbilgin, D.A. Herms, J.A. Hicke, R.W. Hofstetter, S. Katovich, B.S. Lindgren, J. Logan, W. Mattson, A.S. Munson, D.J. Robinson, D.L. Six, P.C. Tobin, P.A. Thowsend and K.F. Wallin. 2009. A literal use of “Forest Health” safeguards against misuse and misapplication. J. Forestry 107: 276-277.

Hayes, C.J., R.W. Hofstetter, T.E. DeGomez, and M. Wagner. 2009. Effects of sunlight exposure and log size on pine engraver (Coleoptera: Scolytidae) reproduction in ponderosa pine slash in Northern Arizona. Agriculture and Forest Entomology 11: 341-350.

Hofstetter, R.W., Z. Chen, M. Gaylord, J. McMillen & M. Wagner. 2008. Synergistic effects of the attractants α-pinene and exo-brevicomin on the southern and western pine beetle and associated predators in Arizona. J. Appl. Entomology 132(5): 387-397.

Hayes, C.J., T.E. DeGomez, J.D. McMillin, J.A. Anhold and R.W. Hofstetter. 2008. Factors influencing pine engraver (Ips pini Say) colonization of ponderosa pine (Pinus ponderosa Dougl. ex. Laws.) slash in Northern Arizona. Forest Ecology and Management 255: 3541-3548.

Gaylord, M.L., K.B. Williams, R.W. Hofstetter, J.D. McMillin, T.E. DeGomez, & M.R. Wagner. 2008. Influence of temperature on spring flight initiation for southwestern ponderosa pine bark beetles (Coleoptera: Curculionidae, Scolytidae). Environmental Entomology 37:57-69.

Pureswaran, D.S., R.W. Hofstetter, & B. Sullivan. 2008. Attraction of the southern pine beetle, Dendroctonus frontalis to pheromone components of the western pine beetle, Dendroctonus brevicomis (Coleoptera: Curculionidae: Scolytinae) in an allopatric zone. Environmental Entomology 37: 70-78.

Martinson, S., M.P. Ayres & R.W. Hofstetter. 2007. Why does longleaf pine have low susceptibility to southern pine beetle? Can. J. For. Research 37: 1966-1977.

Hofstetter, R.W., T.D. Dempsey, K.D. Klepzig & M.P. Ayres. 2007. Temperature-dependent affects on mutualistic and phoretic associations. Community Ecology 8(1): 47-56.

Hofstetter, R.W., K. D. Klepzig, J.C. Moser & M.P. Ayres. 2006. Seasonal dynamics of mites and fungi and interactions with southern pine beetle. Environmental Entomology 35: 22-30.

Kolb, T.E., N. Guerard, M.R. Wagner, and R.W. Hofstetter. 2006. Attack preference of Ips pini in northern Arizona: tree size and bole position. Agriculture and Forest Entomology 8:295-303.

Hofstetter, R.W., J. Cronin, K. D. Klepzig, J.C. Moser & M.P. Ayres. 2006. Antagonisms, mutualisms and commensalisms affect outbreak dynamics of the southern pine beetle. Oecologia 147(4): 679-691.

Hofstetter, R. W., J. Mahfous, K. D. Klepzig, & M.P. Ayres. 2005. Effects of tree phytochemistry on the interactions between endophloedic fungi associated with the southern pine beetle. Journal of Chemical Ecology 31(3): 551-572.

Klepzig, K.D., J. Flores-Otero, R.W. Hofstetter & M.P. Ayres. 2004. Effects of available water on growth and competition of southern pine beetle associated fungi. Mycological Research 108: 183-188.

Lombardero, M.J., R.W. Hofstetter, M.P. Ayres, K. Klepzig & J. Moser. 2003. Strong indirect interactions among Tarsonemus mites (Acarina: Tarsonemidae) and Dendroctonus frontalis (Coleoptera: Scolytidae). Oikos 102: 342-352.

Veysey, J.S., M.P. Ayres, M.J. Lombardero, R.W. Hofstetter & K. Klepzig. 2003. The effect of host species on reproductive success of Dendroctonus frontalis (Coleoptera: Scolytidae). Environmental Entomology 32(2): 668-679.

Klepzig, K.D., J.C. Moser, F.J. Lombardero, R.W. Hofstetter & M.P. Ayres. 2001. Symbiosis & Competition: Complex interactions among beetles, fungi, and mites. Symbiosis 30:83-96.

Klepzig, K.D., J.C. Moser, F.J. Lombardero, M.P. Ayres, R.W. Hofstetter & C.J. Walkinshaw. 2001. Mutualism and antagonism: Ecological interactions among bark beetles, mites and fungi. Pp. 237-267. In: Biotic Interactions in Plant-Pathogen Associations (eds. M.J. Jeger & N.J. Spence). CAB International.

Dr. Hofstetter's publications are also listed at Google Scholar.