US Forest Service, Rocky Mountain Research Station, Logan, UT, USA.
US Forest Service, Rocky Mountain Research Station, Fort Collins, CO, USA.
Environ Entomol. 2024 Oct 11;53(5):837-848. doi: 10.1093/ee/nvae068.
Identifying dormancy traits is important for predicting insect population success, particularly in a changing climate that could disrupt evolved traits. The mountain pine beetle (Dendroctonus ponderosae Hopkins) is native to North America, is responsible for millions of acres of tree mortality, and is expanding northward in Canada. Research has identified thermal traits important to epidemic-phase ecology that vary among populations. Genomic research identified 3 mountain pine beetle haplogroups representing Pleistocene glacial refugia. Significant variation in generation timing aligning with the haplogroups has been observed. The adult stage was previously identified as the likely cause of differences among populations, although the mechanism(s) remain unclear. We tested for an adult summer diapause that varies among populations from 2 haplogroups, southern Colorado (CO) (central haplogroup) and southern Idaho (ID) (eastern haplogroup) using respirometry and reproduction experiments. Warm temperatures (25 °C) resulted in reduced respiration rates of central haplogroup mountain pine beetle compared to a cool temperature treatment (15 °C), whereas respiration of the eastern haplogroup did not differ between the treatments. Mated pairs of central haplogroup mountain pine beetle reared/held at 15 °C were more likely to be classified with a higher reproductive success rating compared to pairs reared/held at 25 °C. These results support a facultative summer adult diapause in southern CO central haplogroup mountain pine beetle. Manifestation of this diapause was low/absent among adults from the northerly ID location. This diapause likely serves to maintain univoltinism shown to be important for mountain pine beetle epidemic-phase ecology. The variation occurring among haplogroups highlights the long-term, evolved processes driving local adaptations in mountain pine beetle.
确定休眠特征对于预测昆虫种群的成功至关重要，特别是在气候变化可能破坏进化特征的情况下。山松甲虫（Dendroctonus ponderosae Hopkins）原产于北美洲，导致了数百万英亩的树木死亡，并正在加拿大向北扩展。研究已经确定了对流行阶段生态学很重要的热特性，这些特性在不同种群之间有所不同。基因组研究确定了代表更新世冰川避难所的 3 个山松甲虫单倍型群。已经观察到与单倍型群一致的世代时间的显著变化。成虫阶段以前被认为是种群之间差异的可能原因，尽管其机制仍不清楚。我们使用呼吸计和繁殖实验测试了来自 2 个单倍型群（科罗拉多州南部（CO）（中心单倍型群）和爱达荷州南部（ID）（东部单倍型群）的种群之间是否存在夏季滞育的差异。与凉爽温度处理（15°C）相比，温暖温度（25°C）导致中心单倍型群山松甲虫的呼吸率降低，而东部单倍型群的呼吸率在两种处理之间没有差异。在 15°C 下饲养/保持的中心单倍型群山松甲虫的交配对更有可能被归类为具有更高繁殖成功率的评级，而在 25°C 下饲养/保持的配对则不然。这些结果支持了在科罗拉多州南部中心单倍型群山松甲虫中存在夏季成虫滞育的可能性。来自北部 ID 地点的成虫中表现出的这种滞育率较低/不存在。这种滞育可能有助于维持山松甲虫流行阶段生态学中很重要的单化现象。单倍型群之间发生的变异突出了长期进化过程驱动山松甲虫的局部适应。
