This rapid assessment shows: 

Diaphania nitidalis is moving in trade and viable larvae have entered the UK, but the risk of establishment in this country is considered to be low. As D. nitidalis requires high temperatures for development, the potential risk to hosts (including the possibility of non-cucurbit hosts) in the UK is small, as the pest must still move into protected cultivation from imported produce in order to overwinter successfully. Containment or eradication is more likely to be achieved in protected cultivation (with appropriate management). However, D. nitidalis is likely to pose a risk to Southern Europe where it may establish outdoors and could severely affect cucurbit production in these areas