The horse-chestnut leaf miner (''Cameraria ohridella'') is a leaf-mining

moth Moths are a group of insects that includes all members of the order Lepidoptera that are not Butterfly, butterflies. They were previously classified as suborder Heterocera, but the group is Paraphyly, paraphyletic with respect to butterflies (s ...

of the

family Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...

Gracillariidae Gracillariidae is an important family of insects in the order Lepidoptera and the principal family of leaf miners that includes several economic, horticultural or recently invasive pest species such as the horse-chestnut leaf miner, ''Cameraria ...

. The horse-chestnut leaf miner was first observed in

North Macedonia North Macedonia, officially the Republic of North Macedonia, is a landlocked country in Southeast Europe. It shares land borders with Greece to the south, Albania to the west, Bulgaria to the east, Kosovo to the northwest and Serbia to the n ...

in 1984, and was described as a new species in 1986.Horse chestnut leaf miner, Cameraria ohridella Desch. & Dem. (Lepidoptera: Gracillariidae)
Exotic pest alert - Uk Forestry Commission Its

larva A larva (; : larvae ) is a distinct juvenile form many animals undergo before metamorphosis into their next life stage. Animals with indirect development such as insects, some arachnids, amphibians, or cnidarians typically have a larval phase ...

e are

leaf miner A leaf miner is any one of numerous species of insects in which the larval stage lives in, and eats, the leaf tissue of plants. The vast majority of leaf-mining insects are moths (Lepidoptera), sawflies (Symphyta, a paraphyletic group which ...

s on the common horse-chestnut (''Aesculus hippocastanum''). The horse-chestnut leafminer was first collected and inadvertently pressed in herbarium sheets by the botanist

Theodor von Heldreich Theodor Heinrich Hermann von Heldreich (3 March 1822 – 7 September 1902) was a German botanist born in Dresden. In 1851, he settled in Greece for the rest of his life. He carried out botanical experiments in the country. He published thirtee ...

in central Greece in 1879.

Damage

''Cameraria ohridella'' causes significant damage, mainly late summer browning, to the appearance of horse-chestnut trees. Despite the poor appearance of these infested trees, there is no evidence that damage by the moth leads to tree death. Seed weight, photosynthetic storage and reproductive capacity may however be reduced.Percival, G. C., Barrow I., Novissa K., Keary I., & Pennington P. 2011. The impact of horse chestnut leaf miner (''Cameraria ohridella'' Deschka and Dimić; HCLM) on vitality, growth and reproduction of ''Aesculus hippocastanum'' L. ''Urban Forestry & Urban Greening''. 10: 11-17 Trees survive repeated infestations and re-flush normally in the following year. It appears that most of the damage caused by the moth occurs too late in the growing season to greatly affect tree performance. Consequently, there is no reason to fell and remove trees just because they are attacked by ''C. ohridella''. The larva feeds in a mine in the leaves of the tree, damaging the leaves and stunting growth. Infected leaves are covered in small brown patches which spread rapidly across the entire tree, giving an autumnal appearance. Eventually the leaves die and drop off; when new ones grow they are again infected. This cycle can repeat itself several times in one season.

Description

The moth is up to long, with shiny, bright brown forewings with thin, silvery white stripes. The hindwings are dark grey with long fringes. Each female moth lays between 20 and 40 eggs singly on the upper surface of leaves, and once these hatch 2–3 weeks later, the

e develop through five feeding phases (or

instar An instar (, from the Latin '' īnstar'' 'form, likeness') is a developmental stage of arthropods, such as insects, which occurs between each moult (''ecdysis'') until sexual maturity is reached. Arthropods must shed the exoskeleton in order to ...

s) and two prepupal (spinning) phases before the pupal phase. The first stage creates a small cavity (or mine) parallel to a vein in the leaf and is "

sap Sap is a fluid transported in the xylem cells (vessel elements or tracheids) or phloem sieve tube elements of a plant. These cells transport water and nutrients throughout the plant. Sap is distinct from latex, resin, or cell sap; it is a s ...

-sipping" rather than " tissue-feeding". By the third instar, the larva creates a mine approximately 8mm in diameter; this is further expanded by later instars until one mine can cover several square centimeters. The larva starts to

pupa A pupa (; : pupae) is the life stage of some insects undergoing transformation between immature and mature stages. Insects that go through a pupal stage are holometabolous: they go through four distinct stages in their life cycle, the stages th ...

te around four weeks after the egg hatches and, except when hibernating as a pupa in the mine, the adult emerges around two weeks later. In severe infestations, the mines of individuals can merge and almost the entire leaf area may be utilised. When this occurs it may lead to high moth mortality as the larvae

compete Competition is a rivalry where two or more parties strive for a common goal which cannot be shared: where one's gain is the other's loss (an example of which is a zero-sum game). Competition can arise between entities such as organisms, individ ...

for space and food. The moth is able to go through up to five generations each year, if the weather is hot and dry; on average in western Europe, the moth goes through three generations each year. The last generation of the year pupates for over six months so as to survive the winter. The pupae are extremely frost tolerant and have been recorded to survive temperatures as low as . This allows its populations to increase even after hard winters. The dead patches that the horse-chestnut leaf miner causes on leaves are similar to damage caused to horse-chestnut trees by the

fungus A fungus (: fungi , , , or ; or funguses) is any member of the group of eukaryotic organisms that includes microorganisms such as yeasts and mold (fungus), molds, as well as the more familiar mushrooms. These organisms are classified as one ...

'' Guignardia'' '' aesculi'', but can be distinguished by the fungal infection often being outlined by a conspicuous yellow band which the mines lack. The pupae can be mistaken for pupae of the genus ''

Phyllonorycter ''Phyllonorycter'' is a genus of moths in the family Gracillariidae. Diversity The genus comprises about 400 species, with a worldwide distribution. The vast majority of species are found in the temperate regions, with about 257 species describe ...

'' but can be distinguished because ''C. ohridella'' pupae do not have a cremaster and the first five abdominal sections have strong lateral spines on them.

Distribution and dispersal

''Cameraria ohridella'' has now been found in

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. Encyclopedia of Life Although horse-chestnut occurs naturally mostly above the contours the moth does well in well-watered places such as parks in cities and at low elevation but not well in the hotter parts of Europe e.g.

. Probably aided greatly by vehicular transport, the moth has attained a very rapid dispersal rate across Europe of per year.Ševrová, H. and Laštúvka, Z. 2001. Control possibility and additional information on the horse-chestnut leafminer ''Cameraria ohridella'' Deschka and Dimić (Lepidoptera, Gracillariidae). ''Acta Universitas Agriculturae et Silviculturae Mendelianae Brunensis''. 13, 121-127Gilbert, M., Grégoire J.-C., Freise, J. F., & Heitland, W. 2004. Long-distance dispersal and human population density allow the prediction of invasive patterns in the horse chestnut leafminer ''Cameraria ohridella''. ''Journal of Animal Ecology''. 73, 459-468

Origin and epidemiology

''Cameraria ohridella'' was first noticed from outbreaks near

Ohrid Lake Lake Ohrid is a lake which straddles the mountainous border between the southwestern part of North Macedonia and eastern Albania. It is one of Europe's deepest and oldest lakes, with a unique aquatic ecosystem of worldwide importance, with more th ...

, Yugoslavia in 1984, and was described as a new species by Deschka and Dimić in 1986. A likely Balkan origin for this moth was evidenced from a decrease in genetic diversity from natural towards artificial horse-chestnut stands that were planted around Europe since around 1600.Valade, R., Kenis, M., Hernandez-Lopez, A., Augustin, S., Mari Mena, N., Magnoux, E., Rougerie, R., Lakatos, F., Roques, A. and Lopez-Vaamonde, C. 2009. Mitochondrial and microsatellite DNA markers reveal a Balkan origin for the highly invasive horse-chestnut leaf miner ''Cameraria ohridella'' (Lepidoptera, Gracillariidae). ''Molecular Ecology'', 18: 3458-3470 This Balkan origin is further documented by numerous herbarium samples that date back to 1879. These include an outbreak which occurred in horse-chestnut specimens collected by F.K. Meyer in 1961 in Albania. Of the 30 known mitochondrial

haplotype A haplotype (haploid genotype) is a group of alleles in an organism that are inherited together from a single parent. Many organisms contain genetic material (DNA) which is inherited from two parents. Normally these organisms have their DNA orga ...

s for the species only three (known as A, B and C) have invaded the rest of Europe since 1989, and only A is dominant. It is likely that the frequency of haplotype A has been increasing even in Balkan natural sites, aided by the late development of roads in the region.

Host plants

As well as colonising the leaves of the common horse-chestnut, ''C. ohridella'' is also able to feed on ''

Aesculus pavia ''Aesculus pavia'', known as red buckeye or firecracker plant (formerly ''Pavia rubra''), is a species of deciduous flowering plant. The small tree or shrub is native to the southern and eastern parts of the United States, found from Illinois to V ...

'', ''

Acer platanoides ''Acer platanoides'', commonly known as the Norway maple, is a species of maple native to eastern and central Europe and western Asia, from Spain east to Russia, north to southern Scandinavia and southeast to northern Iran. It was introduced to ...

'' and ''

Acer pseudoplatanus ''Acer pseudoplatanus'', known as the sycamore in the British Isles and as the sycamore maple in the United States, is a species of maple native to Central Europe and Western Asia. It is a large deciduous, broad-leaved tree, tolerant of wind an ...

'', on which in particular one mitochondrial race, haplotype B, seems to develop successfully when nearby horse-chestnut leaves are exhausted,Péré, C., Augustin S., Turlings T. C. J., & Kenis M. 2010. The invasive alien leaf miner, Cameraria ohridella and the native maple, ''Acer pseudoplatanus'': a fatal attraction?. ''Agricultural and Forest Entomology''. 12: 151-159 but is not thought to pose such a strong risk to these species unlike to the common horse-chestnut.

Control

Parasitoids

Over 60 generalist

parasitoids In evolutionary ecology, a parasitoid is an organism that lives in close association with its host (biology), host at the host's expense, eventually resulting in the death of the host. Parasitoidism is one of six major evolutionarily stable str ...

have been recorded.de Prins W.;de Prins, J. 2005. ''Gracillariidae (Lepidoptera)''. Stenstrup: Apollo Books. However, for biological control a highly specialist parasitoid still needs to be found.

Predators

A number of natural predators of the larval stages of ''C. ohridella'' have been recorded. Observations have shown that

blue tit The Eurasian blue tit (''Cyanistes caeruleus'') is a small passerine bird in the tit (bird), tit family, Paridae. It is easily recognizable by its blue and yellow plumage and small size. Eurasian blue tits, usually resident bird, resident a ...

s (''Cyanistes caeruleus''),

great tit The great tit (''Parus major'') is a small passerine bird in the tit family Paridae. It is a widespread and common species throughout Europe, the Middle East, Central Asia and east across the Palearctic to the Amur River, south to parts of No ...

s (''Parus major'') and

marsh tit The marsh tit (''Poecile palustris'') is a Eurasian passerine bird in the tit family Paridae and genus ''Poecile'', closely related to the willow tit, Père David's and Songar tits. It is a small bird, around long and weighing , with a black ...

s (''Poecile palustris'') feed on the larvae. Between them, three tit species are thought to prey on between 2 and 4% of the larvae. The southern oak bushcricket (''

Meconema meridionale ''Meconema meridionale'' is an insect in the family Tettigoniidae, known as the southern oak bush cricket. It commonly measures 14 to 17 mm in length (not including Antenna (biology), antennae) and is carnivorous, arboreal and nocturnal. I ...

'') has also been found to prey on ''C. ohridella'', consuming around 10 larvae per day. Overall the predation by the southern oak bushcricket is insignificant compared to that by birds however. Experiments with the predatory

mite Mites are small arachnids (eight-legged arthropods) of two large orders, the Acariformes and the Parasitiformes, which were historically grouped together in the subclass Acari. However, most recent genetic analyses do not recover the two as eac ...

'' Euseius finlandicus'', bush crickets ('' Phaneroptera'' sp.),

ladybird Coccinellidae () is a widespread family of small beetles. They are commonly known as ladybugs in North America and ladybirds in the United Kingdom; "lady" refers to mother Mary. Entomologists use the names ladybird beetles or lady beetles ...

s and lacewings found that none prey on ''C. ohridella''.

Procedures

Inadvisably, trees can be removed, or better, leaves cleared and burned before adult emergence by the end of March.Kehrli, P., & Bacher S. 2004. How to safely

compost Compost is a mixture of ingredients used as plant fertilizer and to improve soil's physical, chemical, and biological properties. It is commonly prepared by Decomposition, decomposing plant and food waste, recycling organic materials, and man ...

''Cameraria ohridella'' - infested horse chestnut leaf litter on private compost heaps. ''Journal of Applied Entomology''. 128, 707-709 Use of the systemic

insecticide Insecticides are pesticides used to kill insects. They include ovicides and larvicides used against insect eggs and larvae, respectively. The major use of insecticides is in agriculture, but they are also used in home and garden settings, i ...

imidacloprid Imidacloprid is a systemic insecticide belonging to a class of chemicals called the neonicotinoids which act on the central nervous system of insects. The chemical works by interfering with the transmission of stimuli in the insect nervous system. ...

is usually banned as it kills bees.

Fenoxycarb Fenoxycarb is an insect growth regulator. It has a low toxicity for bees, birds, and humans, but is toxic to fish. The oral LD50 for rats is greater than . Fenoxycarb is non-neurotoxic and does not have the same mode of action as other carbama ...

causes up to 100% pupal mortality, has low environmental toxicity and can be combined successfully with manual leaf removal.Syeryebryennikov, B. 2008. ''Ecology and control of horse chestnut leaf miner'' (Cameraria ohridella). Kiev: Shmalhausen Institute of Zoology. 67 page

/ref> A synthetic pheromone can be used to trap males, Svatoš, Chemical Ecology but effective control may be hard to thus achieve.Svatoš A., Kalinova B., Hoskovec M., Kindl J., Hovorka O., & Hrdy I. 1999. Identification of a new lepidopteran sex pheromone in picogram quantities using an antennal biodetector: (8E,10Z)-tetradeca-8,10-dienal from ''Cameraria ohridella''. ''Tetrahedron Letters'', 40: 7011-7014 In any case, infestation levels could diminish over time as ''Cameraria ohridella'' starts to recruit generalist members of the local parasitoid wasp community.Girardoz, S., Kenis M., & Quicke D. L. J. 2006. Recruitment of native parasitoids by an exotic leaf miner, ''Cameraria ohridella'': host - parasitoid synchronization and influence of the environment. ''Agricultural and Forest Entomology''. 8: 49-56

Projects

A number of projects have been launched to investigate the biology and biological control of ''Cameraria ohridella'' and its impact since 2001, for example, an European Union, EU-wide multidisciplinary project, CONTROCAM ("Control of ''Cameraria''") and th
HAM-CAM Project

References

External links

Taxon page for Cameraria ohridella Deschka & Dimic 1986. In: EOLspecies
in English
HAMburger-CAMeraria-Projekt - Films Photos incl. REM
in German
Cameraria Homepage
in German and English

in English
Forestry Commission Research page
in English

in English

in German
Abstract of HAM-CAM-Projekt, 2003 BBC News report on infestation in Leicester, England, September 2010BBC News report: Citizen science charts horse chestnut tree pest spread, 25 January 2014
{{Authority control Cameraria (moth) Insect pests of temperate forests Moths described in 1986 Moths of Europe Leaf miners Taxa named by Gerfried Deschka Taxa named by Nenad Dimić