Department of Mathematics and Statistics, Utah State University, Logan, UT 84322, USA.
USDA Forest Service, Rocky Mountain Research Station, Logan, UT 84321, USA.
J Insect Sci. 2024 Jul 1;24(4). doi: 10.1093/jisesa/ieae074.
Insects live in a wide range of thermal environments and have evolved species- and location-specific physiological processes for survival in hot and cold extremes. Thermally driven dormancy strategies, development rates and thresholds are important for synchronizing cohorts within a population and to local climates and often vary among populations within a species. Mountain pine beetle (MPB), Dendroctonus ponderosae Hopkins (Coleoptera: Curculionidae, Scolytinae), is a widely distributed forest insect native to North America with clinal genetic differentiation in thermally dependent traits. MPB development occurs in Pinus phloem beneath the bark, and its cryptic habitat makes experimentation difficult, particularly for the adult stage. We describe a novel method for modeling MPB adult development following pupation and terminating in emergence from a brood tree. We focus on an Arizona (southern) MPB population with previously described preadult development rates. Field-observed tree attack, adult emergence, and phloem temperature data are combined in a parameterized cohort model and candidate rate curves are evaluated to describe adult emergence timing. Model competition indicates that the Brière rate curve provided the best fit to field data and performed well under cross-validation. Results confirm that the development of Arizona MPB adults is slower than the previously described development rate of more northern Utah adults. Using the estimated adult rate curve in a scenario of increasing mean temperatures, we show that the timing of second-generation adult emergence in the same year would result in cold-intolerant lifestages during winter, limiting the success of bivoltine populations.
昆虫生活在广泛的热环境中，并进化出了物种特异性和地理位置特异性的生理过程，以在炎热和寒冷的极端环境中生存。热驱动的休眠策略、发育速度和阈值对于在种群内协调群体以及适应当地气候非常重要，而且通常在物种内的不同种群之间存在差异。山松甲虫（MPB），Dendroctonus ponderosae Hopkins（鞘翅目：Curculionidae，Scolytinae），是一种广泛分布于北美的森林昆虫，具有与热依赖特征相关的渐变态遗传分化。MPB 的发育发生在树皮下的松树韧皮部中，其隐蔽的栖息地使得实验变得困难，尤其是对于成虫阶段。我们描述了一种新的方法，用于模拟 MPB 成虫在化蛹后的发育，并以从亲树中孵化出来为终点。我们专注于一个具有先前描述的前期发育速率的亚利桑那州（南部）MPB 种群。实地观察到的树木攻击、成虫出现和韧皮部温度数据被组合在一个参数化的群体模型中，并对候选率曲线进行评估，以描述成虫出现的时间。模型竞争表明，Brière 率曲线最适合野外数据，并且在交叉验证下表现良好。结果证实，亚利桑那州 MPB 成虫的发育速度比以前描述的更北犹他州成虫的发育速度慢。在平均温度升高的情况下，使用估计的成虫率曲线，我们表明同年第二代成虫出现的时间将导致冬季不耐低温的生命阶段，限制了两化性种群的成功。
