Tracing the invasion of a leaf-mining moth in the Palearctic through DNA barcoding of historical herbaria

Historical herbaria are valuable sources of data in invasion biology. Here we study the invasion history of the lime leafminer, Phyllonorycter issikii, by surveying over 15 thousand herbarium specimens of limes (Tilia spp.) collected in the Palearctic during last 253 years (1764-2016). The majority of herbarium specimens with the pest mines (89%) originated from East Asia (1859-2015), whereas remaining 11% of specimens with the mines came from Europe, European Russia and Western Siberia (1987-2015). These results support the hypothesis of a recent Ph. issikii invasion from Eastern to Western Palearctic. Single molecule real-time sequencing of the COI barcode region of 93 archival larvae and pupae (7-162 years old) dissected from the mines on historical herbaria allowed to distinguish between Ph. issikii and Ph. messaniella, a polyphagous species rarely feeding on Tilia, which mines were found in herbarium from Europe dated by 1915-1942. We discovered 25 haplotypes of Ph. issikii, of which 16 haplotypes were present solely in East Asia, and revealed wide distribution of the species in China. Six haplotypes shared between Eastern and Western Palearctic suggest the contribution of Ph. issikii populations from the Russian Far East, China and Japan to the westward invasion.