Department of Renewable Resources, University of Alberta, Edmonton, Alberta, Canada.
Glob Chang Biol. 2024 Mar;30(3):e17207. doi: 10.1111/gcb.17207.
Mountain pine beetles (MPBs) pose a substantial threat to North American pine forests, causing extensive tree mortality over large areas. Their tree-killing ability is closely linked to mass aggregation on host trees triggered via pheromones and dependence on their symbiotic fungi. However, the influence of a changing climate on the biology of MPBs and their co-evolved interactions with their fungal symbionts remains uncertain. To investigate this, male and female pairs of beetles were introduced into freshly cut logs from lodgepole pine trees and placed in controlled climate chambers with manipulated environmental conditions, including two levels of CO (ambient vs. 1000 ppm), O (ambient vs. 100 ppb) and humidity (33% vs. 65%). The beetle-infested logs were left in these chambers for 1 month and then returned to ambient conditions until brood emergence. Emerging broods were collected for further analysis. Additionally, three species of fungal symbionts (Grosmannia clavigera, Ophiostoma montium and Leptographium longiclavatum) were subjected to the same CO , O and humidity conditions for 5 days. Lower humidity promoted MPB reproduction and fungal growth. Elevated CO accelerated larval growth and emergence while improving brood pheromone production. Elevated O had a negative impact on MPB reproduction and brood fitness while improving its immune responses to an entomopathogenic fungus (Beauveria bassiana). It also inhibited fungal growth and reproduction, whereas elevated CO had varied (positive or negative) effects on fungal growth and ergosterol (proxy to fungal mass) production depending on the fungal species. Together, these findings suggest that climate change can potentially alter the interactions between MPBs and their fungal symbionts, highlighting the importance of understanding how climate change affects forest pests and their symbiotic relationships to develop effective management strategies in the future.
高山松树甲虫（MPB）对北美松树林构成了重大威胁，导致大面积树木大量死亡。它们的致死能力与其在宿主树上的大规模聚集密切相关，这种聚集是由信息素触发的，并且依赖于它们共生的真菌。然而，气候变化对 MPB 生物学及其与共生真菌协同进化的相互作用的影响仍不确定。为了研究这一点，将雌雄成对的甲虫引入新鲜砍伐的黑云杉原木中，并将其放置在具有受控环境条件的气候室中，这些环境条件包括两个 CO（环境与 1000ppm）、O（环境与 100ppb）和湿度（33%与 65%）水平。将受甲虫侵袭的原木留在这些气候室中 1 个月，然后返回环境条件，直到幼虫孵化。收集孵化的幼虫进行进一步分析。此外，还将三种共生真菌（Grosmannia clavigera、Ophiostoma montium 和 Leptographium longiclavatum）置于相同的 CO、O 和湿度条件下 5 天。较低的湿度促进了 MPB 的繁殖和真菌的生长。升高的 CO 加速了幼虫的生长和孵化，同时改善了幼虫信息素的产生。升高的 O 对 MPB 的繁殖和幼虫的适应性产生了负面影响，同时提高了其对昆虫病原真菌（绿僵菌）的免疫反应。它还抑制了真菌的生长和繁殖，而升高的 CO 对真菌的生长和麦角固醇（真菌质量的替代物）的产生有不同的（积极或消极）影响，这取决于真菌的种类。总之，这些发现表明，气候变化可能会改变 MPB 与其共生真菌之间的相互作用，强调了了解气候变化如何影响森林害虫及其共生关系以制定未来有效管理策略的重要性。
