Tiltakene for å bekjempelse og kontrollere bestanden av hestekastanjemøll (Cameraria ohridella) i Norge

The topic of this bachelor's thesis is the invasive species horse-chestnut leaf-miner (Cameraria ohridella), its spread in Norway and measures against the horse-chestnut leaf miner that are suitable for Norwegian conditions. The horse-chestnut leaf miner has a parasitic relationship with horse-chestnut tree (Aesculus hippocastanum), the moth's larvae eat the mesophyll of the leaves, which weakness the tree's health, and its ability to winter harden, which increases the chance of frost damage. The flat mines the larvae create also destroy the ornamental value of the tree. If a horse-chestnut tree experiences moth attacks over several years, it will weaken the tree's growth and the tree may eventually die. The aim of the thesis will be to discuss methods to minimize the damage caused by the moth in green outdoor spaces, methods that can combat and control the population of the horse-chestnut leaf miner in Norway and reduce its spread further in the country. The paper will focus on the invasive species horse-chestnut leaf miner, but some of the strategies may be effective against many other species. Therefore, in this thesis, I will also use a literature study to explain the biology and life cycle of the horse-chestnut leaf miner. To gain an understanding of why various measures work and why some do not, and to know how, if necessary, to use the same strategies on other species. Literature studies were also used to explore various measures against the horse-chestnut leaf miner and the advantages and disadvantages of the measures. To gain an insight into measures that have been implemented and experiences people have had with the horse-chestnut leaf miner, I have had conversations with; Oslo and Fredrikstad municipalities, park managers at NMBU, and a person struggling with horse-chestnut leaf-miner in their gardens. My conclusion is that integrated pest management (IPM) and the removal and destruction of fallen leaves in autumn is the most effective options, as of today. As good implementation of IPM will minimize the possibility of attack by the horse-chestnut leaf miner and removal of fallen leaves because it is by remaining in the fallen leaves that the horse-chestnut leaf miner survives the winter. Chemical alternatives are not recommended even if they are used against the horse-chestnut leaf miner in other countries, the use of pesticides in public outdoor places is often illegal in Norway and the consequences of pesticides are not ideal. The biological