Fig 1.
Approximate historical (light grey and mottled grey) and current (light grey and black) extent of mountain pine beetle range in North America.
The light arrow represents current range expansion and dashed arrows represent potential pathways to eastern pine forests. Pine regions shown represent those of pine species used in this study from [33]. Historical and range expansion data obtain from data presented in [24] and the approximate geographic limit of beetle presence reported by the Alberta Ministry of Agriculture and Forestry in 2014.
Table 1.
Mean (SE) diameter at breast height (DBH) (cm) of trees cut (n = 4 per species per year) and mean (SE) phloem thickness (mm) of each species for each of 6 logs cut from the bole of each tree.
Means within a column followed by the same letter are not significantly different.
Table 2.
Proportion of female mountain pine beetles that bored through the bark of six species of pine over a three day period.
Means within a column followed by the same letter are not significantly different.
Fig 2.
Comparison of the mean (+SE) proportion of female beetles entering four live ponderosa pine trees (n = 120 beetles) and logs cut from fiveponderosa pine trees (n = 150 beetles) over a three day period.
Bars within a time period with the same letter are not significantly different.
Fig 3.
Mean (+SE) phloem acceptance and egg gallery establishment.
(A) Mean (+SE) proportion of female beetles accepting phloem after 12 hours when placed into direct contact with phloem through pre-drilled holes. (B) Mean (±SE) proportion of galleries from logs infested with mountain pine beetle with larval galleries present after at least five months. Presence of larval galleries indicates mated pairs accepted the log and laid fertile eggs. Light and dark bars represent historical and novel pine hosts respectively. Bars with the same letter are not significantly different.
Fig 4.
Monte Carlo simulation integrating bark entry, phloem acceptance and egg gallery establishment for cumulative susceptibility.
Percentages indicated the likelihood of a landing beetle establishing a fertile egg gallery. Light and dark bars represent historical and novel hosts respectively. Probability distributions show the middle 95% of the distribution, with upper and lower 2.5% of the tails removed.
Fig 5.
Mean (+SE) number of beetles caught in funnel traps.
Traps were adjacent to various species of logs infested with boring beetles (n = 12 sites) over 2013 and 2014 flight periods. Light grey and dark grey bars differentiate historical and novel hosts respectively. White bars represent the control. Bars with the same letter are not significantly different.
Fig 6.
Total mean (+SE) monoterpene concentration (mg/g of phloem) of six species of pines used in this study.
Samples were extracted from two uninfested logs of each pine within four days of being cut in 2013 with the exception of Scots and lodgepole from which only one was taken, and each of the four trees of each species in 2014. Light and dark bars represent historical and novel hosts respectively. Bars with the same letter are not significantly different.
Fig 7.
Mean (+SE) absolute chemical composition of logs from the six species of pines used in this study.
Samples were extracted from two logs of each pine within four days of being cut in 2013 with the exception of Scots and lodgepole from which only one was taken, and each of the four trees of each species in 2014. Light and dark bars represent historical and novel hosts respectively. Bars with the same letter are not significantly different. Note that scales of y-axis vary between chemicals.
Fig 8.
Mean (+SE) relative concentration of α-pinene in pine logs in relation to the seven primary monoterpenes measured.
Samples were extracted from two logs of each pine within four days of being cut in 2013 with the exception of Scots and lodgepole from which only one was taken, and each of the four trees of each species in 2014. Light and dark bars represent historical and novel hosts respectively. Bars with the same letter are not significantly different.