Linden Moth

Wingspan - 7-7.5 mm. Two morphologically different forms are distinguished - summer and autumn. In the summer form, the face, palps and antennae are white. On the head is a bundle of golden ocher hairs. The chest is golden ocher. The general color of the legs is white. Fore femora and tibia blackish on inner surface. Outside, middle tibia - with three oblique black lines. Middle and hind legs - with black ringlets. Fore wings are lanceolate ocher-golden with white spots. The summer form is similar in color to Phyllonorycter corylifoliclla . In the autumn form, the bundle of hairs on the head is black with separate white scales, sometimes completely white. The chest is dark brown. The front wings are gray ^[2] .

The valva in males are asymmetric, the left - four times narrower than the right. The right valva on top is with spiked setae; on its inner surface there are thin setae. The edeagus is thin ^[2] , its length in European populations is significantly longer than in Asian ^[3] . On the sternum of the seventh segment of the abdomen of females there is a growth ^[4] . Caterpillars are of five ages, each of which ends with molting ^[5] . It is possible to determine the age of a caterpillar by its size ^[5] . On the tip of the abdomen of the pupae there are two spines, the ends of which are curved outward ^[6] .

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  Summer uniform

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  Autumn form

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  Larva

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  Doll

The eggs are oval, 0.32-0.37 × 0.23-0.27 mm in size ^[5] .

Caterpillars of the linden pied moth lead a hidden lifestyle and feed on the leaves of various representatives of the linden genus. They gnaw out in the soft tissues of the cavity sheet - mines. Outwardly, mines appear as swollen, white, rounded spots on the underside of the leaf ^[6] . On one sheet, on average, it takes 4-6 minutes, the maximum is 26 minutes ^[7] .

Within the original range, in the Japanese islands , the moth damages three linden species: Tilia japonica , Tilia kiusiana and Tilia maximowicziana . In the south of the Far East, its food plants include Tilia amurensis and Tilia mandshurica . In Europe, the miner develops in eight species and two hybrids: Tilia americana , Tilia cordata , Tilia × euchlora , Tilia × europea , Tilia mandshurica , Tilia mongolica , Tilia platyphyllos , Tilia taquetii , Tilia tomentosa and Tilia tuan . The reference to nutrition found in the literature on representatives of the genera Birch ( Betula ) and Oak ( Quercus ) is considered erroneous. The choice of the plant is affected by the pubescence of the underside of the leaf. Females avoid laying eggs on pubescent linden species, such as Tilia tomentosa. In Europe, European linden species are much more damaged and species introduced from the primary range of this moth are not populated ^[8] . The white spotted moth in Europe has no direct competitors. Of the 13 insect species that mine the linden leaves, only two ( Stigmella tiliae and Parna tenella ) feed exclusively on linden, but they are rather small species ^[9] .

Linden speckled moth develops over most of the range in two generations . The timing of development depends on weather and climate conditions. The first generation of adults flies from June to July. For the development of this generation, the required sum of effective temperatures is 620–630 ° C. The second generation appears in August and September. Under adverse conditions, moths of the second generation do not have time to complete development ^[10] .

The winter moth spotted moth overwinter at the adult stage. Wintering occurs in cracks in the bark and under the bark, in attics , in firewood and other similar shelters. Departure after wintering approximately coincides with the swelling of the kidneys of the linden. This occurs in late April or early May, when the air warms up above 10 ° C. In the same period, mating occurs. Moths are active at dusk . First generation females lay up to 10 to 52 eggs. Fertility of second generation females varies from 7 to 36 eggs. Eggs are laid individually on the underside of the leaf ^[10] . Egg development lasts from 4 to 8 days (in the Czech Republic ) ^[5] and up to two weeks in Udmurtia ^[10] . After leaving the egg, the caterpillars of the first three ages feed on plant juices, and at the last stages, on the parenchyma of the leaf ^[5] . There are two stages of the formation of mines. At the first stage, a serpentine mine is formed; later, with an increase in the size of the mine, it turns into a spotted mine ^[10] . The caterpillar completes development in 13-40 days, after which it turns into a chrysalis. Under natural conditions, this stage lasts about 10-15 days ^[5] .

The population of leaves within the tree is uneven. The leaves of the lower and outer parts of the crown are most damaged and the density of mines decreases with height and inside the crown. The density of mines decreases with an increase in anthropogenic load ^[11] . At different densities of moths, the ratio of color forms changes. At low density, a more prolific dark form prevails, with a high number, the proportion of light increases ^[12] . At a high density of mines, premature leaf fall may occur and the radial growth of wood and the nectar productivity of the tree may decrease ^[6] .

Parasitoids

Parasitoids can develop both on the surface (ectoparasitoids) and inside the body (endoparasitoids) of the victim. Endoparasitoids predominate in the Asian part of the range, and ectoparasitoids predominate in the European part. According to observations made in Slovakia , Hungary and Udmurtia , infection varies from 15 to 37%. Among parasitoids, the species Minotetrastichus frontalis , Pediobius saulius , Sympiesis gordius and Sympiesis sericeicornis have the greatest influence on the moth population . Among the predatory insects, the moth is fed by the grasshopper Meconema meridionale , the bug Anthocoris nemorum and the staphylin Anthophagus caraboides ^[1] .

List of linden spotted moth parasitoids

Parasitoids of linden spotted moths are 52 species of Hymenoptera. Most parasitoids belong to the family Eulophidae ^{[1] [10] [13]} .

Linden speckled moth was first discovered in 1932 in Ussuriysk , but then these individuals were not correctly identified ^[9] . The scientific description of the species was given by the Japanese lepidopterologist Toshio Kumata on charges on the islands of Hokkaido , Honshu and Kyushu . The species name is given in honor of the Japanese lepidopterologist Suti Issiki. In the description, the species was placed in the genus Lithocolletis ^[2] , and after the recognition of the genus Lithocolletis as a synonym for the genus Phyllonorycter ^{[14] [15],} linden moth spotted got the Latin name Phyllonorycter issiki ^{[16] [12]} . On the island of Shikoku and South Korea, found in 1983. The presence of the species in the south of the Far East was confirmed in 1974. In China, lime motley moth was found only in 2015 in the city of Tianjin ^[3] .

In Europe, linden speckled moth appeared around the period from 1980 to 1984. The first reliable mention of this pest dates back to 1985, it was found immediately in several parks in Moscow . Until the end of the 1980s, moth was discovered in the Moscow and Voronezh regions. In the next 15 years, the range of the species in Europe expanded rapidly. By 2005, it became known in the forests and park areas of cities in the European part of Russia and in the countries of Central Europe ^[9] , the view penetrated to the west to Belgium ^[7] . In 2011, the area of ​​the European part of the range was 4.086 million km² ^[9] . In Siberia, the species was first discovered in 2006 in Tyumen. Targeted pest searches in 2006 and 2007 in Tomsk , Novosibirsk , Irkutsk and regions did not reveal it. The first small population in Novosibirsk was identified only in 2008 ^[6] .

Molecular genetic analysis revealed 31 haplotypes in the range of lime-tree spotted moths, 23 of which were found in the European part of the range and 10 in the Asian part. Two haplotypes were found throughout the range. Analysis of the samples by DNA barcoding showed the presence in the Far East of another undescribed species of speckled moths that feed on linden and does not look different from it ^[3] .

The average rate of expansion of the range is about 42.2 km per year. Extremely hot conditions in 2010 led to a significant decrease in the number of spotted linden moths in Europe, and by 2012, the population of linden moths increased again to 100%. The reasons for the invasion of the species in Europe are considered either the introduction of the pest with seedlings of Far Eastern linden species, or it penetrated with a transit cargo ^[9] .