Analysis of the phytosanitary risk of the pest Agrilus planipennis Fairmaire, 1888 for tree species in Bulgaria

Abstract

Bulgaria is characterized by the fact that it is one of the richest countries in plant diversity in Europe - more than 4,200 higher plant species and about 3,700 species of algae and mosses have been described. On the country territory you can see the last deposits in Europe of a number of rare plant species, as well as another 170 Bulgarian and 200 Balkan endemics. For this reason, the introduction, establishment and spread of new species of plant enemies is a critical moment for the conservation of our nature. Precisely such a species is Agrilus planipennis, which is an East Asian species for which there is currently no evidence of being present in the European Union (EU) territory and in the analyzed threatened area. A. planipennis spreads naturally and through human-assisted routes, such as infested ash logs, firewood and nursery plants. Other potential routes of entry have been identified, such as: wood, sawdust, mulch (composted and uncomposted), and the probability of entry of this enemy is considered moderate. A. planipennis has been added to the A2 list of pests recommended for regulation as quarantine for the EPPO region, meaning that the pest is locally present in the EPPO region. It is also a Union quarantine pest listed in Part A of Annex II to Commission Implementing Regulation (EU) 2019/2072 and a priority pest under Commission Delegated Regulation (EU) 2019/1702, which obliges Member States to carry out annual surveys. Bulgaria falls into an area with suitable eco-climatic conditions for establishment, i.e. in case of possible penetration into the country, the risk of establishing A. planipennis is high. Its current distribution in N. America and European Russia, as well as its native range in Asia, suggests that this species can survive winter at temperatures well below freezing. For this reason, low temperatures in winter are not expected to have a negative impact on the establishment and spread of A. planipennis in Bulgaria, since this species has established itself in areas with much lower temperatures than those in the country (for example, the Moscow region). Given the climatic changes in Bulgaria and the trend towards warming in most regions of the country, and the forecast for milder winters in the coming decades, it is assumed that the conditions will be increasingly suitable. If established and spread, the pest is likely to cause major ecological losses and impacts, as well as some social effects. Long-distance spread will be via human-assisted pathways, and its natural spread will occur, but at a slower rate. In the event of the introduction, establishment and spread of A. planipennis in the country, it could have a negative impact, especially in the areas where the different species of ash are found, and its destruction or containment will be difficult and expensive, and it is unlikely that it would be successful.