Kenneth F. Raffa, Ph.D; UW-Madison Department of Entomology

Top Ten Papers Not Accessible by Most Electronic Searches

Book chapters and proceedings provide great opportunities to integrate empirical results across studies, construct theoretical syntheses, provide data not published due to space limitations, and speculate on general trends. Unfortunately, these often are not easily accessible by standard electronic searches. So I’ve listed 10 such articles below. The complete list is on my full cv, and all pdf’s can be found under ‘All publications’.

Article	Main Points
Raffa, KF, AA Berryman 1980 Flight responses and host selection by bark beetles Pp 213-233 In AA Berryman, L Safranyik, eds Proc 2nd IUFRO conference on dispersal of forest insects: evaluation, theory & management implications Conf Office, Coop Extens Service, Wash St Univ, Pullman WA	- Landing rates on trees that mountain pine beetles subsequently do or do not enter are equivalent primary to onset of aggregation. - Interactions between trees and bark beetles are characterized by conflicting rate processes between plant defense physiology and insect behavior, rather than static relationships or outcomes.
Raffa, KF 1988 Host orientation behavior of Dendroctonus ponderosae: Integration of token stimuli and host defenses Pp 369-390 In WJ Mattson, J Levieux, C Bernard-Dagan, eds Mechanisms of Woody Plant Resistance to Insects and Pathogens Springer-Verlag NY	- Colonization involves a defined sequence of behavioral responses, with distinct cues operating at each stage and scale. - Bioassays need to be interpreted in terms of their specific phase within an overall orientation sequence. - Selection pressures on individual host acceptance behavior may vary with beetle population density.
Raffa, KF 1988 The Mountain pine beetle, Dendroctonus ponderosae in western North America Pp 505-530 In AA Berryman, ed, Population dynamics of forest insects: Patterns, causes and management strategies Plenum Press NY	- Critical thresholds separate endemic from outbreak population dynamics. - Host population is heterogeneous. The number of susceptible hosts is not absolute, but rather is relative to beetle population size. - Initial entry does not guarantee aggregation. Whether aggregation follows is determined by relative rates of initial and induced resin flow vs initial and arriving beetles.
Raffa, KF 1991 Induced defensive reactions in conifer-bark beetle systems Pp 245-276 In DW Tallamy, MJ Raupp (eds), Phytochemical Induction by Herbivores Acad Press NY	- Active, induced responses play crucial roles in conifer-bark beetle-fungal interactions. - Induced defenses are multi-component (multiple chemicals, altered composition and concentration, hypersensitive necrosis). They are integrated with constitutive defenses within an overall resistance system, rather than being isolated mechanisms. - Induced defenses require exposure to biotic agent for full elicitation. - Induced defenses are triggered rapidly enough to affect bark beetle and symbiont success. - There is disproportionately high elicitation of compounds with highest bioactivity.
Raffa, KF KD Klepzig 1992 Tree defense mechanisms against insect-vectored fungi Pp 354-390 In RA Blanchette, AR Biggs, eds Defense Mechanisms of Woody Plants against Fungi Springer-Verlag	- Provides review of insect-vectored fungi and nature of symbioses in trees - Discusses elements of insects and fungi contributing to properties of the complex - Reviews evidence that stress increases susceptibility to bark beetles - Reviews evidence that aggregations exhaust tree defenses - Proposes that differences between entomol and plant pathol view of plant defense arise more from distinct properties of agents than institutional cultures
Raffa, KF, T Phillips, S Salom 1993 Strategies and mechanisms of host colonization by bark beetles Pp 103-128 In TO Schowalter, G Filip, eds Interactions among bark beetles, pathogens, and conifers in North Amer Forests Acad Press	- Bark beetles can be categorized based on host physiological condition at time of colonization. Most species only colonize dead trees or tree parts, most of those that colonize live trees are restricted to stressed hosts, and most generations of those species that kill healthy trees during outbreaks are restricted to stressed trees during lengthy endemics. - Aggregation pheromones have multiple contexts and do not necessarily confer advantage to senders in all systems. Aggregation does not necessarily mean exhaustion of capable tree defenses; appropriate experiments are required to designate function.
Raffa, KF, MR Wagner 1993 Implications of sawfly adaptations to plant-insect interaction theory Pp 547-564 In MR Wagner, KF Raffa (eds), Sawfly Life History Adaptations to Woody Plants Acad Press NY	- Sawflies have intimate relationships with host plants, and so pose special questions relating to the significance of constitutive vs induced resistance, role of physiological stress in susceptibility and suitability, tritrophic interactions, and stable coexistence vs. outbreak dynamics between plants and herbivores.
Kirkendall, LR, DS Kent, KF Raffa 1997 Interactions among males, females and offspring in bark and ambrosia beetles: The significance of living in tunnels for the evolution of social behavior Pp 181-215 In, JC Choe, BJ Crespi, (eds), The Evolution of Social Behavior in Insects and Arachnids Cambridge Univ Press, Cambridge	- Bark and ambrosia beetles show a broad range of mating strategies. - Paternal care and communal breeding are widespread throughout these groups. - Exploiting tissues of live trees, and feeding fungi in dead trees, pose distinct challenges reflected in subsocial, and in at least one case, eusocial behavior.
Raffa, KF 2004 Transgenic resistance in short rotation plantation trees: Benefits, risks, integration with multiple tactics, and the need to balance the scales In, Strauss, SH, HD Bradshaw Pp 208-227 The Bioengineered Forest Challenges for Science and Technology Resources for the Future, Washington DC 245 pp	- Trees pose special challenges for evaluating opportunities and environmental risks of transgenic resistance. The now well-established ‘product not process paradigm’ is useful, but this distinction also means expertise in process does not bring expertise in how products will perform in open ecosystems. - Evaluations are best viewed within a context of multiple spatial and temporal scales, especially interactions across trophic levels, time delays, and feedback. Results obtained at one level of scale, even when mechanistically well defined, do not always predict consequences at larger scales. - Most current evaluations emphasize direct interactions over small scales, and under relatively closed conditions. Improved models are needed.
Raffa KF, Aukema BH, Erbilgin N, Klepzig KD, Wallin, KF 2005 Interactions among conifer terpenoids and bark beetles across multiple levels of scale: An attempt to understand links between population patterns and physiological processes Rec Adv Phytochem 39: 80-118	- Terpenes exert important and varied affects across a range of spatial and temporal scales. - Interactions between conifers and bark beetles are composed of a series of thresholds, each of which poses a significant barrier, but once breached may no longer exert substantial effects on lower scale processes. These interactions often show Allee effects at multiple levels. - We present three case studies, in which populations of various species simply track host stress, exert some positive feedback on a small scale, or pass a critical threshold beyond which positive feedback totally dominates. These three relationships yield different effects on forest structure, resulting in crown thinning, gap formation, and landscape-scale stand replacement / alteration of successional trajectories, respectively. - Comparison of these case studies suggests that competitors, predators, and habitat heterogeneity can help constraint low-density bark beetle populations within a range in which they are susceptible to host resistance.

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