Cameraria ohridella Deschka & Dimic, 1986
Aesculus hippocastanum, Hungary, Mosonmagyaróvár © László Érsek
Aesculus hippocastanum, Nieuwendam; a lightly infested leaf
Aesculus hippocastanum, Arnhem; even this is a rather light infestation
Aesculus hippocastanum, Domburg: larva in the mine; © Camiel Doorenweerd
Aesculus hippocastanum, Nieuwendam; egg shell and initial corridor. The egg mostly is deposited near a vein, while as a rule the mine doesn’t cross thicker veins. As a result the egg and corridor are generally not run over by the later blotch, but remain at its outer margin.
Aesculus hippocastanum, Nieuwendam; a similar picture, lighted from behind, of a young mine. The egg shell has not yet dried, and is very transparent (under a favourable illumination a hexagonal surface structure sometimes is visible).
Aesculus flava, Putten, Schovenhorst: this species was lightly infested
The mine begins at a flat, oval, somewhat iridescent egg shell at the upperside of the leaf. There starts an epidermal corridor of some mm, that abruptly widens into an upper-surface blotch. The blotch is elongate, often confined between by a pair of lateral veins; its colour is cinnamon, with a darker centre. The frass is not granular, like in Phyllonorycter species, but consists of a tarlike substance covering the floor of the mine. The number of mines can be as much as several tens per leaf. Pupation occurs within the mine.
Horse chestnut is the primary host plant. Only here and there populations are found on Maple, and then only when Chestnuts are not far away (see also Péré ao, 2010a). Larvae on Aesculus x carnea did not live longer than the first instar (Milevoj, 2004a).
Larvae from mid-May till October. Already in mid-June the lower branches may be so heavily attacked that leaves are dropped. Hibernation as pupa, in the fallen leaves.
BE first observation in 2000 (W & J De Prins, 2001a).
NE observed in the Netherlands since 1998 (Stigter ao, 2000a; van Nieukerken, 2001a).
LUX recorded (Fauna Europaea, 2010).
distribution within Europe
All Europe. The species was discovered as recently as 1985 in Macedonia (it specific name refers to Lake Ohrid). Therefore, and also because it is the only known representative in Europe of the genus Cameraria, one has long assumed that it concerned a recent introduction from North America, where a number of species of this genus are known to occur. A problem with this hypothesis was that ohridella was not known from North America (Lakatos ea, 2005a). A recent study by Valade ao (2009a) has unequivocally demonstrated now that ohridella indeed is a European species. Moreover, a study of herbarium material has demonstrated that the species occurs in Europe since 1879 at least (Lees ao, 2011a).
Since its discovery the species has in a very short time invaded almost all Europe.
Aesculus hippocastanum, Nieuwendam; early stage of infestation (early summer). The species forms a threat for the many ornamental Horse Chestnut trees in our region. The infestation begins at the lower branches. Later in summer also the higher parts of the crown are attacked, and in autumn there is total defoliation.
The trees in the picture above are particularly hit because their feet are in an ornamental dense shrub. Fallen leaves are trapped here in autumn; the cannot be removed and are not blown away. Because the pupae hibernate in these fallen leaves the infestation already is maximal in spring.
The mines should not be confused with leaf spots caused by the fungus Phyllosticta paviae (= Guignardia aesculi); these have a much more brick-red colour, often seamed bright yellow, are larger, and more irregular in shape. The spores of this fungus germinate in spring on leaves that are moistened by rain, and infestation can be particularly heavy after a rainy spring.
See Freise & Heitland (1999a), Pschorn-Walcher (1994a) and Skuhravy (1999a) for the biology of this species. Heitland, Kopelke & Freise (2003a) summarise the research of possible control measures.
When the density of mines becomes so large that they touch each other (meaning that the available leaf material is almost finished) the pupae go into diapause, even though the season is not far advanced. This enables ohridella to optimise the utilisation of the available food (Sefrová 2001b; Sefrová & Laštuvka, 2001a).
an essential element in the moulting of insect larvae is the mid-dorsal split of the integument. As Grebennikov found, Cameraria forms an exception to that rule. Possibly as an adaptation to the limited space available in the mine, here the integument splits at a side of the body, upon which the larva creeps out of its old skin by lateral movements. But in the latest moult, from larva to pupa, that place in a cocoon, the integument splits dorsally!
Augustin (2005a), Baldizzone (2004a), Bengtsson & Johansson (2011a), Braggion (2013a), Buszko & Beshkov (2004a), Csóka (2001a, 2003a), Deutschmann (2008a), Dietrich (2007a), Diškus & Stonis (2012a), Freise & Heitland (1999a), Grabenweger ao (2007a), Grebennikov (2013a), Heitland, Kopelke & Freise (2003a), Huemer & Erlebach (2003a), Ianovici, Matica & Scurtu (2010a), Jaworski (2009a), Johne, Weißbecker & Schütz (2006a), Kirichenko, Augustin & Kenis (2018a), Kollár (2007a), Kollár & Hrubík (2009a), Lakatos ao (2005a), Lees ao (2011a), Leutsch (2011a), Maček (1999a), Matošević, Pernek, Dubravac & Barić (2009a), Milevoj (2004a), Nel, Leraut, Nel & Varenne (2003a), Nel & Varenne (2014a), van Nieukerken (2001a), Parenti & Varalda (2000a), Patočka & Turčáni (20005a), Péré, Augustin, Tomov ao (2010a), Péré, Augustin, Turlings & Kenis (2010a), Plóciennik, Pawlikiewicz & Jaworski (2011a), De Prins (2004a), De Prins, De Prins & De Coninck (2003a), W & J De Prins (2001a), Pröse (1995a), Pschorn-Walcher (1994a), Reichholf (2004a), Roques, Cleary, Matsiakh & Eschem (2017a), Sefrová (2001b, 2005a), Sefrová & Laštuvka (2001a), Sefrová & Skuhravy (2000a), Skuhravy (1999a), Stammer (2016a), Stigter ao (2000a), Tomov & Krusteva (2007a), Ureche (2010a), Valade, Kenis, Hernandez-Lopez ao (2009a), Werner, Irzykowska & Karolewski (2012a), Wołczańska & Mułenko (2002a).