Comparisons of mountain pine beetle (Dendroctonus ponderosae Hopkins) reproduction within a novel and traditional host: effects of insect natal history, colonized host species and competitors

Abstract

1 During host-breadth expansion, phytophagous insects incur risk from potentially deleterious novel host environments at the same time as potentially securing a potential escape in space or time from competing species. 2 Bark beetles reproduce under the bark of stems and branches of mature, stressed or moribund trees, and may suffer high mortality from plant defences and inter-and intraspecific competition. 3 An epidemic of mountain pine beetle (Dendroctonus ponderosae Hopkins) in western Canada has extended to over 18.1 million hectares of lodgepole pine (Pinus contorta Douglas ex. Loudon) forests. 4 In some areas, mountain pine beetles have been found to reproduce within interior hybrid spruces [Picea glauca (Moench) Voss × engelmannii Parry ex. Engelmann], a normally rare occurrence. 5 Using mountain pine beetles reared from naturally-infested interior hybrid spruce and lodgepole pine hosts, we examined the effect of female natal species and colonized host species on the ability to attract mates and reproduce within spruce and pine logs deployed as a choice assay in a field setting. Additionally, we examined whether the arrival and reproduction of competitors such as pine engravers (Ips spp.) was associated with reduced brood production. 6 Females reared from pine and spruce exhibited similar reproductive potentials.Recruitment and establishment of ovipositional galleries, larval galleries and pupal chambers were similar in the typical and novel hosts. 7 Reproduction by mountain pine beetles in spruce, although successful, was significantly lower than in pine. This reduction occurred despite spruce logs being almost entirely free of competing secondary beetles.

Management for Mountain Pine Beetle Outbreak Suppression: Does Relevant Science Support Current Policy?

“…Mountain pine beetle attacks only pines (except in rare instances where it "bleeds over" into spruce) [67], and typically only those larger than ca. 15 cm in diameter [68].…”

Performance of the tree‐killing bark beetles Ips typographus and Pityogenes chalcographus in non‐indigenous lodgepole pine and their historical host Norway spruce

“…By contrast, the reproduction of I. typographus in stem sections of the exotic red spruce, Engelmann spruce and Lutz spruce was comparable with the reproduction in Norway spruce (Økland et al ., ), which may be a result of these tree species being more closely related to the historical host Norway spruce as discussed above. In accordance with this, the reproductive success of the mountain pine beetle in the naïve host tree species jack pine and red pine is similar to the success in its historical host, lodgepole pine, whereas it was lower in interior hybrid spruce (McKee et al ., ; Erbilgin et al ., ; Cale et al ., ). One factor that should be addressed in future studies is the ability of fungal associates of bark beetles to colonize non‐indigenous tree species.…”

“…Tree‐killing bark beetles may also colonize and reproduce in novel host tree species. Reported examples include the Eurasian spruce bark beetle Ips typographus (L.) in the North American Engelmann spruce, white spruce, Sitka spruce, Lutz spruce, black spruce and red spruce (Økland et al ., ); the mountain pine beetle Dendroctonus ponderosae in jack pine, red pine and interior hybrid spruce (McKee et al ., ; Erbilgin et al ., ; Cale et al ., ); and the red turpentine beetle Dendroctonus valens in Chinese red pine (Yan et al ., ; Liu et al ., ).…”

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

“…Late stage mortality could have also occurred from desiccation of the hosts, as novel hosts contained slightly thinner phloem than historical hosts in the second year of the study (Cerezke, ; Rosenberger, Aukema, et al., ). Mortality could have also been due to a lack of symbiotic micro‐organisms or latent toxic effects of the host—important areas that require further study (Bentz & Six, ; Clark, Huber, & Carroll, ; McKee, Huber, & Aukema, ; Therrien et al., ).…”