Tracing the Invasion of Takecallis nigroantennatus (Hemiptera, Aphididae) on Cold-Hardy Bamboo Fargesia Using Mitochondrial COI Data

The introduction of alien insect species is increasingly facilitated by global plant trade, particularly through the movement of ornamental plants. <i>Takecallis nigroantennatus</i>, a host-specific aphid associated with cold-hardy <i>Fargesia</i> bamboo, has recently expanded its range in Europe. To examine its invasion dynamics, we conducted a population-level survey across 13 locations in six countries, sampling individuals from botanic and private gardens, specialized bamboo nurseries, garden centers, and urban horticultural environments in the UK, Belgium, The Netherlands, Germany, Poland, and Norway. A total of 117 specimens were analyzed using mitochondrial COI sequences, revealing a single dominant haplotype without geographic structure based on Bayesian and Maximum Likelihood phylogenetic analyses. This striking genetic uniformity indicates a narrow introduction bottleneck, suggesting a single or highly restricted introduction event followed by clonal spread. Despite the species' ability for sexual reproduction, the data support a founder effect and rapid recent expansion closely linked to the introduction history of <i>Fargesia</i> in Europe. The results are also consistent with a possible time lag between the arrival of ornamental bamboo and the subsequent establishment of its associated herbivore, a scenario that warrants further investigation. Importantly, our study provides a practical framework for applied monitoring and early detection in bamboo nurseries, botanical gardens, and other high-risk introduction sites, illustrating how molecular tools can inform biosecurity and the management of emerging invasive species.