The invasive alien leaf miner <i>Cameraria ohridella</i> and the native tree <i>Acer pseudoplatanus</i>: a fatal attraction?

1. The horse-chestnut leaf miner <i>Cameraria ohridella</i> is an invasive moth in Europe and a serious pest of horse-chestnut <i>Aesculus hippocastanum</i>. The moth also occasionally attacks sycamore maple <i>Acer pseudoplatanus</i>, when situated beside infested horse-chestnuts. <br> 2. The main objective of the present study was to provide an overview of the relationship between <i>C. ohridella</i> and <i>A. pseudoplatanus</i> and to determine whether <i>C. ohridella</i> has the potential to shift to this native tree. <br> 3. In the field, females oviposit on different deciduous tree species. Although less frequently attacked than <i>A. hippocastanum</i>, <i>A. pseudoplatanus</i> was clearly preferred for oviposition over 12 other woody species investigated. <br> 4. Surveys in Europe demonstrated that the majority of <i>A. pseudoplatanus</i> trees found beside infested <i>A. hippocastanum</i> had mines of <i>C. ohridella</i>, even though more than 70% of the larvae died within the first two instars. Attack rates and development success greatly varied from site to site. Attack levels on <i>A. pseudoplatanus</i> were not always correlated with those on <i>A. hippocastanum</i>, and mines on <i>A. pseudoplatanus</i> were sometimes observed beside weakly-infested <i>A. hippocastanum</i>. <br> 5. Field observations, experimental exposure of <i>A. pseudoplatanus</i> saplings and rearing trials in a common garden study showed that individual trees may vary in their susceptibility to <i>C. ohridella</i>, whereas there was no evidence that <i>C. ohridella</i> populations vary in their performance on <i>A. pseudoplatanus</i>. <br> 6. To date, there is little evidence that <i>C. ohridella</i> represents a major risk for <i>A. pseudoplatanus</i>.