Applied Chemical Ecology of the Western Pine Beetle, an Important Pest of Ponderosa Pine in Western North America

Abstract

Western pine beetle (Dendroctonus brevicomis LeConte) is a major cause of ponderosa pine (Pinus ponderosa Dougl. ex. Laws.) mortality in western North America. Twenty-first century epidemics are among the largest in history and have affected hundreds of thousands of hectares. We synthesize literature on the chemical ecology of western pine beetle and on efforts to exploit our understanding of the western pine beetle-ponderosa pine system to reduce host tree losses. This literature dates back to the early 20th century and focuses on populations in California and Oregon, U.S., where western pine beetle exerts its largest impacts. Research in the 1960s–1970s yielded an effective semiochemical attractant (exo-brevicomin, frontalin, and myrcene) that helped inform understanding of the biology, ecology, and management of this species. Later, research focused on isolation and identification of semiochemical repellents. To date, Verbenone Plus (acetophenone, (E)-2-hexen-1-ol + (Z)-2-hexen-1-ol, and verbenone) is the only semiochemical repellent demonstrated effective for protecting ponderosa pines from mortality attributed to western pine beetle in multiple studies in Canada and the U.S.

Composition of Attractant Semiochemicals of North American Species of Dendroctonus Bark Beetles: A Review

“…Importantly, attractants that mediate massaggregation are essential to the ability of the more aggressive species to colonize healthy trees [18,19], since only with sufficient numbers of attacks can the beetles neutralize the resin defenses of vigorous hosts [20,21]. Due to the potential of semiochemicals to alter bark beetle behavior in beneficial ways, there have been extensive efforts to incorporate synthetic semiochemicals into technologies for pest management [22][23][24]. Bark beetle attractants are used for delimiting the range of individual species [25,26], assessing diversity of bark beetles and their natural enemies [27][28][29], detecting inadvertent introductions of exotic pest species [30][31][32][33], forecasting beetle population trends [34][35][36], mass trapping and "trap tree" procedures for population reduction [37][38][39][40], "push-pull" tactics with both attractants and repellants for protecting resource patches [39,41,42], creating snags for wildlife habitat [43,44], and addressing a wide range of research questions.…”