The fast invasion of Europe by the box tree moth: an additional example coupling multiple introduction events, bridgehead effects and admixture events

Abstract

Identifying the invasion routes of non-native species is crucial to understanding invasions and customizing management strategies. The box tree moth, Cydalima perspectalis, is native to Asia and was recently accidentally introduced into Europe as a result of the ornamental plant trade. Over the last 15 years, it has spread across the continent and has reached the Caucasus and Iran. It is threatening Buxus trees in both urban areas and forests. To investigate the species’ invasion routes, native and invasive box tree moth populations were sampled, and moth’s genetic diversity and structure were compared using microsatellite markers. Our approximate Bayesian computation analyses strongly suggest that invasion pathways were complex. Primary introductions originating from eastern China probably occurred independently twice in Germany and once in the Netherlands. There were also possibly bridgehead effects, where at least three invasive populations may have served as sources for other invasive populations within Europe, with indication of admixture between the two primary invasive populations. The bridgehead populations were likely those in the countries that play a major role in the ornamental plant trade in Europe, notably Germany, the Netherlands, and Italy. All these invasion processes likely facilitated its fast expansion across Europe and illustrate the role played by the ornamental plant trade not only in the moth’s introduction from China but also in the species’ spread across Europe, leading to an invasion with a complex pattern.

Demographic study of the box tree moth Cydalima perspectalis (Lepidoptera: Crambidae) feeding on Buxus hyrcana (Buxales: Buxaceae)

“…The first report of C. perspectalis in Iran came from the Northern provinces of Guilan and Mazandaran (Ahangaran, 2016;Farahani et al, 2016). Genetic analyses suggest that the most plausible route of introduction was commercial trade of infested ornamental box trees between China and Europe, whereas plant trade among European countries could lead to its rapid spread (Bras et al, 2022).…”

“…The first report of C. perspectalis in Iran came from the Northern provinces of Guilan and Mazandaran (Ahangaran, 2016; Farahani et al, 2016). Genetic analyses suggest that the most plausible route of introduction was commercial trade of infested ornamental box trees between China and Europe, whereas plant trade among European countries could lead to its rapid spread (Bras et al, 2022). Since females lay their transparent and flattened eggs in clusters on the lower surface of leaves, they are barely visible and can be easily missed (Hizal et al, 2012; Leuthardt & Baur, 2013).…”

Out of East Asia: Early Warning of the Possible Invasion of the Important Bean Pest Stalk-Eyed Seed Bug Chauliops fallax (Heteroptera: Malcidae: Chauliopinae)

“…These effects will then trigger a self-accelerating process of invasion [ 1 ]. Additionally, it is controversial whether it is due to mutations that have gained a strong invasive ability or due to multiple admixture events [ 1 , 17 ]. However, it is worth noting that whichever reasons enhance the invasion ability, the short stay at the beginning of the invasion process exists for many invasive species [ 18 , 19 ].…”

Wing Shape Variation between Terrestrial and Coastal Populations of the Invasive Box Tree Moth, Cydalima perspectalis, in Croatia

“…Indigenous to China, Korea, and Japan, C. perspectalis primarily feeds on species of the genus Buxus, which are commonly utilized as ornamental plants across the globe. The rampant trade of ornamental plants has been identified as a key factor responsible for the species' invasive spread in Europe [11]. Possessing rapid propagation rates and strong adaptability, C. perspectalis made its European debut in 2007 in southwestern Germany and the Netherlands [12].…”