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We present the results of the first-ever DNA barcoding study of odonates from the Maltese Islands. In total, 10 morphologically identified species were collected during a two-week long expedition in 2018. Eighty cytochrome c oxidase subunit I (COI) barcodes were obtained from the collected specimens. Intra- and interspecific distances ranged from 0.00% to 2.24% and 0.48% to 17.62%, respectively. Successful species identification based on ascribing a single morphological species to a single Barcode Index Number (BIN) was achieved for eight species (80%). In the case of two species, Ischnura genei and Anax parthenope, BINs were shared with other closely related species. The taxonomic status of I. genei is questionable and the phylogenetic relationship between A. imperator/parthenope is not clear. Further studies involving a series of adult specimens collected in a wide spatial range and nuclear markers are necessary to resolve these cases. Therefore, this dataset serves as an initial DNA barcode reference library for Maltese odonates, within a larger project: Aquatic Macroinvertebrates DNA Barcode Library of Malta.

The nativity of Populus alba in the Mediterranean has only been confirmed in the last decade, following the discovery of 8,000-year-old leaf imprints in Southern France. Recent evidence has even emerged from molecular studies suggesting that the species is native to some of the islands, and these populations may be relicts of a native flora that arrived there much earlier than previously thought. In view of this, samples obtained from the Central Mediterranean archipelago of Malta and other neighbouring regions were analysed to determine the native status of the Maltese populations and possibly trace their origins. All 38 samples were investigated in order to assess the genetic diversity and origin of Maltese trees. Nuclear microsatellite analysis revealed that all 28 trees sampled from the two islands of Malta belonged to one clone. Chloroplast data suggested relatedness of the Maltese clone to Italian P. alba samples. However, nuclear data suggested additional admixture through pollen from North Africa. Existing archival and palaeontological records were also examined for any supporting evidence. On considering the latter records in combination with molecular evidence, we arrived to the conclusion that arrival of this clone in Malta through human introduction in the sixteenth century is the most likely explanation, since alternative scenarios like autovegetative propagation or arrival by seed seem highly unlikely.

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Phytosanitary legislation is widely thought to be the most effective means of limiting the entry of alien pathogens without hindering trade. However, there is increasing evidence of limitations and weaknesses in phytosanitary systems worldwide. One such case is the entry and establishment of Colletotrichum acutatum in the UK in the 1980s. To investigate this further, data sets of disease incidence gathered by the authorities responsible for plant health between 1984 and 2008 were analysed to determine how and why the pathogen entered the UK and became established on strawberries. Results suggest that the disease entered the UK in 1982 on plants originating from the USA, a year earlier than the first UK record of the disease was reported. At least 54 further cases of infested plant material breached phytosanitary procedures and entered the UK, 75% of which originated from EU countries. Moreover, internal trade transmission was found to be highly influential in the successful spread of the disease. The effectiveness of phytosanitary procedures is limited when the sector is importing large numbers of plants from nurseries that have a track record of selling infested plant material, even if they are accompanied by a plant passport. By taking greater responsibility in limiting the spread of quarantine diseases, nurseries throughout the EU have an important role to play in limiting the entry of alien pathogens.