Just Michael G, Frank Steven D
Department of Entomology and Plant Pathology, North Carolina State University, Raleigh, NC.
Environ Entomol. 2020 Feb 17;49(1):104-114. doi: 10.1093/ee/nvz154.
An insect species' geographic distribution is probably delimited in part by physiological tolerances of environmental temperatures. Gloomy scale (Melanaspis tenebricosa (Comstock)) is a native insect herbivore in eastern U.S. forests. In eastern U.S. cities, where temperatures are warmer than nearby natural areas, M. tenebricosa is a primary pest of red maple (Acer rubrum L.; Sapindales: Sapindaceae) With warming, M. tenebricosa may spread to new cities or become pestilent in forests. To better understand current and future M. tenebricosa distribution boundaries, we examined M. tenebricosa thermal tolerance under laboratory conditions. We selected five hot and five cold experimental temperatures representative of locations in the known M. tenebricosa distribution. We built models to predict scale mortality based on duration of exposure to warm or cold experimental temperatures. We then used these models to estimate upper and lower lethal durations, i.e., temperature exposure durations that result in 50% mortality. We tested the thermal tolerance for M. tenebricosa populations from northern, mid, and southern locations of the species' known distribution. Scales were more heat and cold tolerant of temperatures representative of the midlatitudes of their distribution where their densities are the greatest. Moreover, the scale population from the northern distribution boundary could tolerate cold temperatures from the northern boundary for twice as long as the population collected near the southern boundary. Our results suggest that as the climate warms the M. tenebricosa distribution may expand poleward, but experience a contraction at its southern boundary.
一种昆虫的地理分布可能部分受到环境温度生理耐受性的限制。暗黑蛎盾蚧（Melanaspis tenebricosa (Comstock)）是美国东部森林中的一种本土食草昆虫。在美国东部城市，那里的温度比附近的自然区域更高，暗黑蛎盾蚧是红枫（Acer rubrum L.；无患子目：无患子科）的主要害虫。随着气候变暖，暗黑蛎盾蚧可能会扩散到新的城市或在森林中成为有害生物。为了更好地了解暗黑蛎盾蚧当前和未来的分布边界，我们在实验室条件下研究了暗黑蛎盾蚧的耐热性。我们选择了五个高温和五个低温实验温度，这些温度代表了已知暗黑蛎盾蚧分布区域的地点。我们建立了模型，根据暴露于温暖或寒冷实验温度的持续时间来预测蚧虫死亡率。然后我们使用这些模型来估计上下致死持续时间，即导致50%死亡率的温度暴露持续时间。我们测试了来自该物种已知分布的北部、中部和南部地点的暗黑蛎盾蚧种群的耐热性。蚧虫对代表其分布中纬度地区（其密度最大）的温度更耐热和耐寒。此外，来自北半分布边界的蚧虫种群耐受来自北半边界低温的时间是在南半边界附近采集的种群的两倍。我们的结果表明，随着气候变暖，暗黑蛎盾蚧的分布可能会向极地扩展，但在其南半边界会出现收缩。
