Fig 1.
Locations of parent mountain pine beetle population sources and tree harvest sites.
Two mountain pine beetle-infested limber pines were cut from Nevada and one infested lodgepole pine was cut from Utah to obtain two populations of unmated mountain pine beetle adults for use in tests. Live, uninfested Great Basin bristlecone and limber pines were cut from the Humboldt-Toiyabe National Forest and the Dixie National Forest sites (a single tree of each species from each site), and one live, uninfested lodgepole pine was cut from the Uinta-Wasatch-Cache National Forest site. Shown on the map are observed points of Great Basin bristlecone pine occurrence (data from Bentz et al., 2016 [22]) and limber and lodgepole pine distributions [32].
Table 1.
Summary of model information for all statistical tests.
Fig 2.
Male (M) and female (F) parent mountain pine beetle size from the Nevada and Utah populations.
Shown are the median (solid middle line), 25th and 75th percentiles (top and bottom of box), ± 1.5 x the interquartile range (whiskers), and all outliers (points). N = number of beetles in each category.
Fig 3.
Phloem thickness of bolts cut from each of the five host trees that were manually infested with mountain pine beetle parents.
HT = Humboldt-Toiyabe National Forest site, DX = Dixie National Forest site, UWC = Uinta-Wasatch-Cache National Forest site. All eight bolts from each of the Great Basin bristlecone and limber pine trees were used in phloem thickness calculations but only four of the eight lodgepole pine bolts were used due to missing data. Shown are the median (solid middle line), 25th and 75th percentiles (top and bottom of box), ± 1.5 x the interquartile range (whiskers), and all outliers (points).
Fig 4.
Total fecundity measured by the sum of larval galleries (hatched eggs) and eggs that had not yet hatched for each parent gallery.
HT = Humboldt-Toiyabe National Forest site, DX = Dixie National Forest site, UWC = Uinta-Wasatch-Cache National Forest site; NV = Nevada beetle population, UT = Utah beetle population. Shown are the median (solid middle line), 25th and 75th percentiles (top and bottom of box), ± 1.5 x the interquartile range (whiskers), and all outliers (points). N = number of parent galleries in each category.
Fig 5.
Cumulative total numbers of emerged offspring by host tree and mountain pine beetle population for the entire emergence period, unadjusted for slightly differing numbers of successful parent galleries in each host tree.
BR = Great Basin bristlecone pine, LM = limber pine, LP = lodgepole pine; HT = Humboldt-Toiyabe National Forest site, DX = Dixie National Forest site, UWC = Uinta-Wasatch-Cache National Forest site. Emerging offspring were collected from six individually infested bolts of each host tree starting at day 50 through day 100 after infestation and until either five consecutive days had passed with no newly emerged offspring from the bolt or until day 150 was reached. Note Y axis limit is only 100 for Great Basin bristlecone pine graphs but Y axis limit is 1,500 for graphs for other tree species.
Fig 6.
Average total number of emerged offspring per successful parent gallery by host tree for days 50 through 100 after infestation.
HT = Humboldt-Toiyabe National Forest site, DX = Dixie National Forest site, UWC = Uinta-Wasatch-Cache National Forest site. In both Great Basin bristlecone pines, the average total number of offspring per successful parent pair was <1. There were six bolts of each host tree. Results from Utah and Nevada beetles are combined because there was no significant difference in average total number of emerged offspring per successful parent gallery between mountain pine beetle populations. Shown are the median (solid middle line), 25th and 75th percentiles (top and bottom of box), ± 1.5 x the interquartile range (whiskers), and all outliers (points).
Fig 7.
Male (M) and female (F) offspring mountain pine beetle size from the Nevada and Utah populations.
To standardize the emergence period across all bolts, only mountain pine beetles that emerged days 50–100 were used in size calculations. Shown are the median (solid middle line), 25th and 75th percentiles (top and bottom of box), ± 1.5 x the interquartile range (whiskers), and all outliers (points). N = number of beetles in each category.
Fig 8.
Female offspring size by host tree and mountain pine beetle population.
HT = Humboldt-Toiyabe National Forest site, DX = Dixie National Forest site, UWC = Uinta- Wasatch-Cache National Forest site; NV = Nevada beetle population, UT = Utah beetle population. Female offspring from the Great Basin bristlecone pines were significantly smaller than those from the limber pines, and females from HT Great Basin bristlecone pine were significantly smaller than females from lodgepole pine. Male offspring size was not significantly different between host trees. Shown are the median (solid middle line), 25th and 75th percentiles (top and bottom of box), ± 1.5 x the interquartile range (whiskers), and all outliers (points). N = number of beetles in each category.