Bark beetles are associated with diverse communities of symbionts. Although fungi have received significant attention, we know little about how bacteria, and in particular their interactions with fungi, affect bark beetle reproduction. We tested how interactions between four bacterial associates, two symbiotic fungi, and two opportunistic fungi affect performance of mountain pine beetles (Dendroctonus ponderosae) in host tissue. We compared beetle performance in phloem of its historical host, lodgepole pine (Pinus contorta), and its novel host recently accessed through warming climate, jack pine (Pinus banksiana). Overall, beetles produced more larvae, and established longer ovipositional and larval galleries in host tissue predominantly colonized by the symbiotic fungi, Grosmannia clavigera, or Ophiostoma montium than by the opportunistic colonizer Aspergillus and to a lesser extent, Trichoderma. This occurred in both historical and naïve hosts. Impacts of bacteria on beetle reproduction depended on particular fungus–bacterium combinations and host species. Some bacteria, e.g., Pseudomonas sp. D4–22 and Hy4T4 in P. contorta and Pseudomonas sp. Hy4T4 and Stenotrophomonas in P. banksiana, reduced antagonistic effects by Aspergillus and Trichoderma resulting in more larvae and longer ovipositional and larval galleries. These effects were not selective, as bacteria also reduced beneficial effects by symbionts in both host species. Interestingly, Bacillus enhanced antagonistic effects by Aspergillus in both hosts. These results demonstrate that bacteria influence brood development of bark beetles in host tissue. They also suggest that climate-driven range expansion of D. ponderosae through the boreal forest will not be significantly constrained by requirements of, or interactions among, its microbial associates.
|Original language||English (US)|
|Number of pages||19|
|State||Published - Oct 22 2015|
Bibliographical noteFunding Information:
This project was funded by the USDA-Agriculture and Food Research Initiative (2003-3502-13528), and, in part, through post-graduate scholarships at the University of Alberta and from the Natural Sciences and Engineering Research Council of Canada—Discovery Grant, an Alberta Advanced Education and Technology Grant, and a Canada Research Chair Program awarded to NE. We thank Dr. Kathy Bleiker (Pacific Forestry Centre, Victoria, BC) for her valuable suggestions and feedback. Pam Melnick and Devon Letourneau from the Alberta Environment and Sustainable Resources Development helped us to set traps to collect live beetles. We thank two anonymous reviewers for helpful comments that improved our manuscript.
© 2015, Springer-Verlag Berlin Heidelberg.
- Bark beetles
- Host colonization
- Invasion biology
- Jack pine