Colonization behaviors of mountain pine beetle on novel hosts: Implications for range expansion into northeastern North America

Abstract

As climates change, thermal limits may no longer constrain some native herbivores within their historical ranges. The mountain pine beetle, Dendroctonus ponderosae Hopkins, is a tree-killing bark beetle native to western North America that is currently expanding its range. Continued eastward expansion through the newly invaded and novel jack pine (Pinus banksiana Lamb.) trees of the Canadian boreal forest could result in exposure of several species of novel potential host pines common in northeastern North America to this oligophagous herbivore. Due to the tightly co-evolved relationship between mountain pine beetle and western pine hosts, in which the insect utilizes the defensive chemistry of the host to stimulate mass attacks, we hypothesized that lack of co-evolutionary association would affect the host attraction and acceptance behaviors of this insect among novel hosts, particularly those with little known historical association with an aggressive stem-infesting insect. We studied how beetle behavior differed among the various stages of colonization on newly cut logs of four novel potential pine host species; jack, red (P. resinosa Ait.), eastern white (P. strobus L.) and Scots (P. sylvestris L.) pines, as well as two historical hosts, ponderosa (P. ponderosa Dougl. ex. Laws. var. scopulorum Engelm.) and lodgepole (P. contorta Dougl. var. latifolia Engelm.) pines. Overall, we found that beetle colonization behaviors at each stage in the colonization process differ between pine hosts, likely due to differing chemical and physical bark traits. Pines without co-evolved constitutive defenses against mountain pine beetle exhibited reduced amounts of defensive monoterpenoid chemicals; however, such patterns also reduced beetle attraction and colonization. Neither chemical nor physical defenses fully defended trees against the various stages of host procurement that can result in tree colonization and death.

Inter‐country trade, genetic diversity and bio‐ecological parameters upgrade pest risk maps for the coconut hispid Brontispa longissima

“…For each of the above nations, potential invasion pathways are different yet can be clearly illuminated. Countries such as India and Bangladesh border B. longissima ‐affected nations and may thus be subject to natural dispersal of the pest, possibly aided by increased climatic variability . Invasion risk in countries such as Brazil or Mexico, however, will depend on long‐distance trade of live palms, a well‐recognized driver of tree‐killing pest invasions .…”

“…Countries such as India and Bangladesh border B. longissima-affected nations and may thus be subject to natural dispersal of the pest, possibly aided by increased climatic variability. 42 Invasion risk in countries such as Brazil or Mexico, however, will depend on long-distance trade of live palms, a well-recognized driver of tree-killing pest invasions. 43 Such a threat can only be counteracted by upgrading country-specific regulations for live plant imports and tightening quarantine and biosecurity measures.…”

Development of an aggressive bark beetle on novel hosts: Implications for outbreaks in an invaded range

“…Previous work (Furniss & Schenk, 1969;Rosenberger, Venette, Maddox, et al, 2017) has shown that mountain pine beetle will attack congeneric host material, despite substantial phylogenetic distances from historical hosts (e.g. red and Scots vs. ponderosa and lodgepole pine) and a lack of shared co-evolutionary history (Bertheau et al, 2010).…”

“…All trees were c. 24 cm diameter at breast height (DBH, c. 1.3 m above ground) and free of visible signs of insect or disease. In 2013 and 2014, logs of common north eastern pines, jack, red, eastern white, and Scots pines were obtained from the Cloquet Forest Research Center, MN (Rosenberger, Venette, Maddox, & Aukema, 2017). The historical hosts, lodgepole and ponderosa pine, were obtained from the Big Horn Mountains in Wyoming and Black Hills in South Dakota respectively (Rosenberger, Venette, Maddox, et al, 2017).…”

“…Mountain pine beetles to seed the logs were caught in 12-funnel Lindgren funnel traps baited with commercial pheromone lures (Contech Enterprises Inc, Delta, BC) in ponderosa pine forest near Silver City, SD (Rosenberger, Venette, Maddox, et al, 2017). Beetles were collected daily and sexed with a repetitive audible method (Rosenberger, Venette, et al, 2016).…”