Frank Steven D, Just Michael G
Department of Entomology and Plant Pathology, Campus Box 7613, North Carolina State University, Raleigh, NC 27695, USA.
Insects. 2020 Feb 25;11(3):142. doi: 10.3390/insects11030142.
Sleeper species are innocuous native or naturalized species that exhibit invasive characteristics and become pests in response to environmental change. Climate warming is expected to increase arthropod damage in forests, in part, by transforming innocuous herbivores into severe pests: awakening sleeper species. Urban areas are warmer than natural areas due to the urban heat island effect and so the trees and pests in cities already experience temperatures predicted to occur in 50-100 years. We posit that arthropod species that become pests of urban trees are those that benefit from warming and thus should be monitored as potential sleeper species in forests. We illustrate this with two case studies of scale insects that are important pests of urban trees in parts of the US. and are geographically native to the US but take on invasive characteristics such as higher survival and reproduction and become disconnected from natural enemies on urban trees due to the urban heat island effect. This allows them to reach high densities and damage their host trees. density increases up to 12 times on urban willow oaks with just 2 °C of warming due to higher survival and adaptation to warmer temperatures. The urban heat island effect also creates a phenological mismatch between and its parasitoid complex, and so egg production is higher. density can increase 300 times on urban red maples with 2.5 °C of warming. This too is due to direct effects of warmer temperatures on survival and fecundity but also benefits from the drought stress incurred by warmer urban trees. These effects combine to increase density in forests as well as on urban trees at latitudes higher than its native range. We illustrate how cities provide a unique opportunity to study the complex effects of warming on insect herbivores. Studying pestilent urban species could be a pragmatic approach for identifying and preparing for sleeper species.
潜伏物种是无害的本地或归化物种，它们具有入侵特性，并会因环境变化而成为害虫。预计气候变暖将部分通过将无害的食草动物转变为严重害虫来增加森林中的节肢动物损害：唤醒潜伏物种。由于城市热岛效应，城市地区比自然地区更温暖，因此城市中的树木和害虫已经经历了预计在50至100年后才会出现的温度。我们认为，成为城市树木害虫的节肢动物物种是那些受益于变暖的物种，因此应作为森林中的潜在潜伏物种进行监测。我们通过两个关于介壳虫的案例研究来说明这一点，介壳虫是美国部分地区城市树木的重要害虫。[物种名称1]和[物种名称2]在地理上原产于美国，但具有诸如更高的生存和繁殖等入侵特性，并且由于城市热岛效应，在城市树木上与天敌失去联系。这使它们能够达到高密度并损害其寄主树木。由于更高的存活率和对温暖温度的适应，[物种名称1]在城市柳栎上仅升温2°C时密度就增加了12倍。城市热岛效应还导致[物种名称1]与其寄生蜂复合体之间出现物候不匹配，因此产卵量更高。在城市红枫上升温2.5°C时，[物种名称2]的密度可增加300倍。这同样是由于温暖温度对生存和繁殖力的直接影响，但[物种名称2]也受益于城市树木变暖导致的干旱胁迫。这些影响共同导致[物种名称2]在高于其原生范围的纬度地区的森林以及城市树木上的密度增加。我们说明了城市如何提供了一个独特的机会来研究变暖对昆虫食草动物的复杂影响。研究城市害虫物种可能是识别和为潜伏物种做准备的一种务实方法。
