A pest from list A2. Belongs to the family Dendrolimus sibiricus. For EU countries also in the A2 list. It damages conifers, especially larch, fir, pine, but can also damage hemlock. First of all, fir and larch. Larch is the most resistant, while fir, on the contrary, suffers the most. It is quite widespread throughout the entire territory of the Russian Federation; it was included in the list of quarantine due to other countries. Native species of Siberia, the Far East, the Urals. In addition, it is found in Kazakhstan, Mongolia, China and Korea. Pretty large butterfly, does not feed. The wingspan reaches 10 cm in females, 4-6 in males. The color of the wings varies greatly: from light yellow-brown to almost brown. Males are more darkly colored like avilo. Antennae feathery. The caterpillars are also quite large, the last instars can reach 8-10 cm in length. The pupa is dark brown or black, it weaves a gray-brown cocoon, which is either in the branches or in the grass. The mass flight of the Siberian silkworm has been observed since mid-July and continues intensively for 30-40 days. After mating, females can fly up to several kilometers. Prefer elevated and less wet places, select trees. There they lay eggs on needles mainly in the lower part. If there is a breeding outbreak, then eggs can be laid almost anywhere. And at the fallen trunks, and in the litter. Fertility is maximum up to 800 eggs, but usually 200-300 eggs. The caterpillars hatch rather quickly, they begin to roost in late July-early August. In hungry years, dry needles and young branches can also be damaged. The generation of this species is 2-3 years, but the duration of development varies. Typically - 2 years, at the stage of 2-3 instars the larva hibernates. In the spring they climb trees again and feed on needles there again. The detection technique is the method of nearing trees. During outbreaks of mass reproduction, silkworms are easily detected from the air. In addition, a pheromone was synthesized, which is used in traps. The range of one trap is at least 2 km. If the forest is inspected for lumber, eggs and cocoons can be found. Distribution - independently constantly expanding its range to the west and north. On their own, butterflies can fly for several kilometers, and with the wind for a year - up to 15 ki. Caterpillars can independently crawl 3 km per season. The area for the year will increase by 12 km. This species is often spread, including in the trade of transport materials and the transport that transports it. Often in unrooted logs, prva and bedding seedlings. Stage - egg, caterpillar or cocoon. Strongly affects the forests of Siberia and daiengo alstok. Phytosanitary measures: when the outbreaks of the Siberian silkworm are detected, measures are taken to localize this outbreak. In the areas where it was detected - a quarantine phytosanitary regime. Accordingly, a thorough inspection is carried out from the places of injury. In the quarantine phytosanitary zone, aquarantine restrictions are introduced. All year round conifers from May to September should be debarked. If it is impossible to pass, fumigation. Planting material from bonaay to fir trees is prohibited for export from May to September.

Japanese beetle. Lamellar. distributed in the eastern part of North America and on Sakhalin Island. Homeland - Southeast Asia, China, Korea and Japan. From there, he entered the United States and Canada. Recorded in India, Morocco, and on one island of Portugal. In the Russian Federation, it is stable on the island of Kunashir. If it penetrates into the Asian part of the country, it will be able to capture significant territories and the northern borders will pass through St. Petersburg, the Urals, Novosibirsk and Khabarovsk. Polyphage, damages about 300 species of fruit and berry, field, vegetable, ornamental and deciduous. The beetle is 7-10 mm, the pronotum is bright green in color with a metallic sheen, and the elytra are brown with a copper sheen. The larva is S-shaped, up to 2.5 cm long at the last instar. The larva of 2-3 instars hibernates in the soil. The larvae feed on roots. They pupate in the middle of summer. Beetles roughly load leaves, can gnaw flowers, fruits to the bone. Fruit crops are severely affected. The larvae no less severely harm field and vegetable crops. Plants are weakened, there is a fall of plants in the form of bald patches. The beetle flies well, spreads over several kilometers, and the larvae spread in plant material. To identify, an inspection of the green parts of the plant, cut plants and bouquets from distribution areas is carried out in the period from June 15 to September 30. If there is fresh food products from Asian countries, they also inspect it. Against them, they are treated with insecticides, into the soil - systemic, in granules.

Nematode

Colombian potato root nematode.

The main economically significant pest in the United States. It was first found on the roots and tubers of potatoes in the vicinity of Quincy. There are also reports of detection in Europe, the Netherlands, Jabelgia, Germany, Portugal. In 1988, it was included in the EPPO list. In Russia - the object of external quarantine. Morphology: Females are globular to pear-shaped, with a bulge at the posterior end. They are immobile, have a silvery-white color. The body of males is thin, worm-like. Eggs have transparent walls.

IN temperate latitudes cycle is about 3-4 weeks. Soil temperature is less important for this species. Slow reproduction occurs already at a temperature of 10 degrees Celsius. Optimal conditions - 15-20 degrees. Early infection greatly affects the quality of potatoes. No more than 10% defeat for sale. characteristic feature is that the eggs are formed on the surface. Preserved in the form of eggs. The typical plant is kratofel, however, it can also develop on cereals, root crops, legumes, etc. Symptoms are only visible when the infection is severe. Leaves may show chlorotic coloration. Careful inspection of products from countries with reported cases. Fight - destruction, resistant varieties are very few and they are not on potatoes.

Let's talk about Siberian silkworm- This is a species of butterfly that lives in coniferous forests. It is quite large in size, for example, its wingspan reaches sixty - eighty millimeters for the female, and forty - sixty centimeters for the male. It belongs to the family of cocoons. Its caterpillars feed on coniferous trees. She especially prefers such trees as: larch, spruce, ordinary pine and fir.

A distinctive feature of the male is his antennae, they have a feathery shape. Butterfly wings have Brown color with different shades: yellow, gray and black. The front wings, if you look closely, have three stripes, usually dark color, and in the middle there is a large speck white color. The wings that are behind are mostly one-color.

Butterflies begin to fly from mid-July, and their flight lasts until mid-August.

What kind of eggs do they have? About two millimeters in diameter, in the form of a ball. If you look at them, then on each egg you can see a brown dot, and the color of the eggs itself is green with blue and turns into gray. There may be thirty, forty or more in one clutch, sometimes up to two hundred. Eggs develop over about thirteen days, sometimes up to twenty-two. After that, from mid-August, a caterpillar comes out, its food is needles. She lives for herself, feeds and develops into a more adult individual. In the month of September, towards the end, the caterpillar prepares for wintering. It hibernates under moss and fallen needles, being in a state of complete rest. In the spring, when the snow has melted, the caterpillar crawls into the crowns, where it lives there all the time until autumn.

The length of the caterpillar is approximately fifty-five to seventy millimeters. It is usually brown or brown.

The caterpillar actively feeds and, having accumulated the necessary food elements, in June it wraps itself in cocoons, which are very dense and have a gray color. The pupa develops over a period of three to four weeks.

The pupae reach a length of twenty-eight centimeters - thirty-nine. The color of the pupa is light, then turns into brown, with time, as it grows, it becomes almost black.

In Russia, the Siberian silkworm lives within the Urals, also in Siberia, where there are especially many coniferous trees. It spread over a fairly large area. It is also common in Asia: Kazakhstan, Mongolia and other countries. The difference in temperature does not frighten him much and therefore it is distributed from Siberia to Asia and beyond. This type of silkworm is considered a pest of forest trees. The distribution of the Siberian silkworm to the west is also noted.

At Siberian silkworm there are enemies - these are riders, braconids, egg-eaters, ibraconids. These natural enemies destroy the Siberian silkworm, regulating their numbers. He has something to eat, where to live, he breeds, like everything else in nature, and has his enemies. Such a description revealed more to us the diverse and surprisingly harmonious world of nature.

Svetlana Lapshina

Unexpectedly, almost all of Siberia this year was covered by a silkworm. The cedar forests suffered in the Kemerovo region (pests were registered on an area of ​​about 12 hectares), in Irkutsk (about 50 thousand hectares), in the Krasnoyarsk Territory (about 1 million hectares).

- It was the youngest cedar. Average age trees 100-120 years old, - Alexander Boltovsky, a district forester of the Bogashevskoye forestry, sighs, pointing towards the field. - The silkworm caterpillars ate this tree completely. In 32 years of work, this is the first time I see this.

Instead of a chic green crown, there are only bare branches - not a single needle on the tree. And there are dozens of such cedars ...

caterpillars attack

The Siberian silkworm destroyed two areas of plantings in the Luchanovsky settlement cedar forest (total area of ​​almost 18 hectares) in three weeks of August. Local boys, climbing cedars for cones, told the forester: “Some worms are crawling upstairs.” But the experienced Boltovsky was already in the know.

- I walked around these foci ten times, calculated the area affected by the silkworm. The most important thing is to prevent the pest from spreading to next year. In the spring, it is necessary to carry out the processing of these territories, and especially those areas that are adjacent to healthy plantations, explains Alexander Boltovsky.

There are about 5 thousand hectares of cedar forests in the Bogashevskoye forestry. Problems have arisen so far only in the vicinity of the village of Luchanovo.

Now the pest has left for the winter. We easily found silkworm caterpillars in the forest floor.

“There are so many of them,” Alexander Boltovsky demonstrates a harmful crop in his palm. - It seems that the caterpillars are dead? Nothing like this. Now they are in a state of suspended animation. And here is the cocoon. An adult individual of the Siberian silkworm will come out of it.

There is a chance the trees will survive. Because the overeating was a one-time and in autumn period. And the buds from which the needles grow are still alive.

Silkworm gave heat

The Siberian silkworm is a habitual inhabitant of our forests. With a low number, it does not pose a danger. However, favorable weather conditions for it - last year's warm winter and a long hot summer - provoked an uncontrolled population growth. As a result, in the Tomsk region, at the same time, centers of damage to cedars flared up in Bakcharsky, Verkhneketsky, Pervomaisky, Tomsk, Parabelsky, Kolpashevsky, Chainsky, Molchanovsky and Kozhevnikovsky districts.

Siberian silkworm outbreaks most often occur after two to three dry growing seasons. In such years, the most viable and prolific individuals appear, characterized by particular voracity.

- The territory affected by the pest is at least 424 thousand hectares. None of the experts expected such a rapid development of events, - explains Anton Balaburkin, Chief Specialist of the Department of Protection and Protection of the Forest Fund of the Regional Forestry Department.

But this is not yet the final figure. Surveys in the region will last until the end of December. They are conducted by forest rangers and forest pathologists from the Forest Protection Center. The main task is to find out the boundaries of the outbreak and the number of the pest. Now experts are planning to examine the forest in the Teguldet region.

“It is very difficult but necessary work. It makes it possible to see the whole picture as a whole, - continues Anton Balaburkin.

Experts determine the number of Siberian silkworms by rounding several trees. They count the number of caterpillars that have fallen and, based on this data, draw conclusions about the threat of overeating. This indicator is necessary for planning actions to eliminate the centers of defeat of cedars for the next year. If the threat of overeating is 50% or more, special measures must be prescribed. When the silkworm caterpillar stops feeding and goes into the litter, forest pathologists excavate.

- A thousand caterpillars on a tree - this is not the limit. In some areas of the Bazoisky cedar forest of the Kozhevnikovsky district, their number on cedars reached two thousand. And six hundred caterpillars are enough for one hundred percent overeating, - comments Anton Balaburkin.

give to nuts

Almost 450 million rubles are needed to save the cedar forests. It is planned to allocate about 50 million from the regional budget for the next year to fight the Siberian silkworm. Therefore, the regional authorities turned to the Federation for support: Governor Sergei Zhvachkin wrote a letter to Rosleskhoz.

– It is impossible to write off the social significance of the cedar forests. Most of them are suburban, that is, they are located near settlements. And for many local residents, harvesting pine nuts is the main source of income, - Anton Balaburkin emphasized.

The ideal option is to treat the entire affected area. The optimal time for such work is the first decade of May. At this time, the caterpillars emerge from the litter, rise into the crown and begin to feed actively. And at this moment it is necessary to strike from the air - to spray with the help of air transport special means.

The Siberian silkworm is poisoned with the biological preparation Lepidocid. It is harmless to humans and animals, including bees.

- IN this moment we're trying to get on federal level permission to use chemical control agents. Biological preparations are effective, but they have a very serious limitation - the temperature of application, - notes Anton Balaburkin. – Lepidocide operates at an average daily temperature of 18 degrees and above, and in early May it will be plus 10 at most.

The problem lies in the fact that all Russian chemicals have expired certification periods - they need to be extended. And this also takes time. IN Soviet years there were more than 20 different means allowed for use. Tomichi appealed to the government with a request to use at least some of them.

The amount of work to be done is very large. But success will be achieved only if everything works out: federal money will come to the region, competitive procedures will be successfully completed ... The invaluable property of the region is at stake - His Majesty the Siberian cedar.

The caterpillar of the Siberian silkworm has six instars. The main nutrition occurs from the third age. For the third - fourth, the caterpillar eats at least 30% of the crown of the tree, for the fifth - sixth - everything else. In the Tomsk region there are areas where overeating is 100%.

In our region, there was an outbreak of mass reproduction of the Siberian silkworm in the mid-1950s. Then the silkworm damaged about 1.5 million hectares of taiga. The north-east of the region was especially affected.

The Siberian silkworm feeds on the needles of almost all coniferous species found within its range. Prefers larch, often damages fir and spruce, to a lesser extent Siberian and common pines.

The development cycle of the Siberian silkworm usually lasts two years.

In the second half of July, the summer of butterflies begins, it lasts about a month. Butterflies don't eat.

The female lays on average about 300 eggs, placing them one by one or in groups on needles in the upper part of the crown.

In the second half of August, caterpillars of the first age emerge from the eggs, they feed on green needles, and in the second or third age, at the end of September, they leave for wintering. Caterpillars overwinter in the litter under the cover of moss and a layer of fallen needles.

The rise in the crown is noted in May after the snow melts. Caterpillars feed until next autumn and leave for the second wintering at the fifth or sixth age. In spring, they again rise to the crowns and after active feeding in June weave a dense gray cocoon, inside which they then pupate. The development of the silkworm in the chrysalis lasts 3-4 weeks.

Siberian silkworm

cedar silkworm (Dendrolimus sibiricus), a butterfly of the cocoonworm family, a dangerous pest of coniferous forests. Wingspan up to 90 mm, gray color. Distributed S. sh. off the coast Pacific Ocean to V. to Southern Urals in the west and from Yakutia in the north to northern China in the south. It damages larch, fir, cedar, rarely spruce, and pine. The first butterflies appear at the end of June, the mass flight begins, as a rule, in mid-July and ends in the first half of August. N. sh. has a two-year or one-year generation. With a two-year generation, the number of caterpillar ages is 7-8, with a one-year generation - 5-6. Most of the caterpillars overwinter in the forest litter at the 3rd instar (in larch plantations more often at the 2nd instar). After the snow cover melts, they feed on needles, eating it entirely. Sometimes kidneys and even young cones are damaged. Eating needles is one of the reasons for the mass reproduction of stem pests (especially barbels), which damage plantations and lead to their death. Regulates the number of S. sh. its common natural enemy telenomus rider. mass death caterpillars S. sh. usually occurs as a result of epizootics caused by bacteria.

Control measures: the most effective spraying of foci of S. sh. during caterpillar development younger ages aircraft insecticides. See also Art. Forest pests.

Lit.: Forest entomology, M., 1965.

N. N. Khromtsov.

Great Soviet Encyclopedia. - M.: Soviet Encyclopedia. 1969-1978 .

See what the "Siberian silkworm" is in other dictionaries:

Butterfly of the cocoonworm family; pest of coniferous tree species in Siberia, on Far East. Wings are grey. It feeds (caterpillars) on needles, buds, young cones ... Big Encyclopedic Dictionary

SIBERIAN SILKMOTH, a butterfly of the cocoonworm family; pest of coniferous tree species in Siberia, the Far East. Wings are grey. It feeds (caterpillars) on needles, buds, young cones ... encyclopedic Dictionary

SILKMOTH, a, husband. 1. Butterfly, caterpillar to a swarm weaves cocoons, going to the manufacture of silk (in 1 meaning). Mulberry sh. 2. Butterfly, caterpillar to the swarm is a pest of the forest. Siberian sh. Pine sh. Explanatory dictionary of Ozhegov. S.I. Ozhegov, N.Yu. Shvedova… … Explanatory dictionary of Ozhegov

Cedar silkworm (Dendrolimus sibiricus), a butterfly of the fam. cocoonworms. Wingspan up to 90 mm. Butterflies and caterpillars are similar to those of the pine cocoon moth. In Siberia, in the Far East, in the North. Mongolia, Sev. China, Korea, Japan. Mass flight in the 2nd ... Biological encyclopedic dictionary

A; m. 1. Butterfly, the caterpillar of which weaves cocoons, which are used to make silk (1 sign). Mulberry sh. 2. Butterfly, the caterpillar of which is a dangerous pest of tree plantations. Unpaired sh. Kedrovy sh. Siberian sh … encyclopedic Dictionary

silkworm- A; m. 1) a butterfly, the caterpillar of which weaves cocoons that are used to make silk 1) Silkworm / d. 2) Butterfly, the caterpillar of which is a dangerous pest of tree plantations. Gypsy moth/d. Cedar silkworm/d. Siberian silkworm / d ... Dictionary of many expressions

Siberian silkworm (Dendrolimus superans sibiricus Tschetv.)

Siberian silkworm (Dendrolimus superans sibiricus Tscetv.) in the Asian part of Russia is one of the most dangerous pests of coniferous forests, especially in Siberia and the Far East. Periodic large-scale outbreaks of mass reproduction of this phytophage lead to significant changes in the structure of taiga forests, destruction of forest stands and change of forest formations.

The centers of mass reproduction are observed annually on an area from 4.2 thousand to 6.9 million hectares (0.8 million hectares on average) and cause significant damage to forestry. Therefore, satellite monitoring as a part of entomological monitoring of forests is an important element in monitoring the state of forest cover, which, if properly performed, ensures the preservation of the most important ecological functions of forests.

In Russia, a huge contribution to the development and implementation of biological methods to combat the centers of mass reproduction of the Siberian silkworm was made by Prof. Talalaev E.V. In the mid-1990s, extensive forest plantations in Western and Eastern Siberia, as well as in the Far East, suffered from the silkworm. In the Krasnoyarsk Territory alone, for four years, the outbreak covered the territories of 15 forestries, the area of ​​damaged taiga plots amounted to more than 600 thousand hectares. Destroyed a large number of valuable cedar plantations. Over the past 100 years in the territory Krasnoyarsk Territory 9 outbreaks of the pest were registered. As a result, over 10 million hectares of forests were damaged. The use of modern insecticidal pyrethroid and bacterial preparations allowed to partially localize the foci of the pest and stop its further spread.

At the same time, the danger of a new mass reproduction of the Siberian silkworm remains.

In the period between outbreaks, the silkworm lives in reservations - areas with the most favorable development conditions. In the zone of dark coniferous taiga, the reservations are located in mature, quite productive (grade II-III class) stands of forb-green-moss forest types with the participation of fir up to 6 units and more, with a density of 0.3-0.6.

Imago of the Siberian silkworm. Photo: Natalia Kirichenko, Bugwood.org

　

The Siberian silkworm is a large butterfly with a wingspan of 60-80　mm for the female and 40-60　mm for the male. Color varies from light yellowish brown or light gray to almost black. The forewings are crossed by three darker stripes. In the middle of each wing there is a large white spot, the hindwings are the same color.

Females lay eggs on needles, mainly in the lower part of the crown, and during periods of very large numbers - on dry branches, lichens, grass cover, and forest litter. In one clutch, there are usually several dozen eggs (up to 200), and in total the female can lay up to 800 eggs, but most often the fecundity does not exceed 200-300 eggs.

The eggs are almost spherical in shape, up to 2　 mm in diameter, at first bluish-green in color with a dark brown dot at one end, then greyish. Egg development lasts 13-15 days, sometimes 20-22 days.

Caterpillars of the Siberian silkworm have different colors. It varies from gray-brown to dark brown. The body length of the caterpillar is 55-70　 mm, on the 2nd and 3rd body segments they have black transverse stripes with a bluish tint, and on the 4-120th segments there are black horseshoe-shaped spots (Fig.).

The first molt occurs after 9-12 days, the second after 3-4. At the first age, the caterpillars eat only the edges of the needles; at the second age, they eat the entire needles. At the end of September, the caterpillars burrow into the litter, where they hibernate under the moss cover.

At the end of April, the caterpillars rise into the crowns of trees and begin to feed, eating whole needles, and with a lack of food, the bark of thin shoots and young cones. About a month later, the caterpillars molt for the third time, and in the second half of July - again. In autumn they leave for the second wintering. In May-June of the following year, adult caterpillars feed intensively, causing the greatest harm. During this period, they eat 95% of the food necessary for full development. They molt 5-7 times and go through 6-8 instars accordingly.

Caterpillars feed on the needles of almost all conifers. But they prefer fir, spruce, larch. Cedar is damaged to a lesser extent, pine is even less damaged. In June, caterpillars pupate; before pupation, the caterpillar weaves a brown-gray oblong cocoon. Pupa, 25-45　 mm long, brownish red, then dark brown, almost black. The development of the pupa depends on temperature and lasts about a month. The massive summer of butterflies takes place in the second decade of July. On the southern slopes of the mountains, it passes earlier, on the northern slopes - later.

The development cycle of the Siberian silkworm usually lasts 2 years. But in the south of the range, development almost always ends in one year, and in the north and in high-mountain forests, sometimes there is a three-year generation. Butterfly flight begins in the second half of July and lasts about a month. Butterflies don't eat. The wingspan of females is from 6 to 10 cm; males are 4-5 cm. Unlike females, males have feathery antennae. The female lays on average about 300 eggs, placing them one by one or in groups on needles in the upper part of the crown. In the second half of August, caterpillars of the first age emerge from the eggs, feed on green needles, and in the second or third age they leave for wintering at the end of September. Caterpillars overwinter in the litter under the cover of moss and a layer of fallen needles. The rise in the crown is noted in May after the snow melts. Caterpillars feed until next autumn and leave for the second wintering at the fifth or sixth age. In spring, they again rise to the crowns and after active feeding in June weave a dense gray cocoon, inside which they then pupate. The development of the silkworm in the chrysalis lasts 3-4 weeks.

In the dark coniferous taiga, silkworm foci form after several years of hot, dry weather in summer. In this case, the caterpillars leave for wintering later, at the third or fourth age, and turn into butterflies the next summer, moving to a one-year development cycle. The acceleration of the development of caterpillars is a condition for the formation of centers of the Siberian silkworm.

Plot of coniferous forest after defoliation by the Siberian silkworm. (Photo by D.L. Grodnitsky).

　

Forest area defoliated by the Siberian silkworm (photo: http://molbiol.ru)

Accounting for wintering caterpillars in the litter is carried out in October or early May. The number of caterpillars in the crown is determined by the method of rounding on cloth canopies in early June and late August.

The age of the caterpillars is set according to the table, measuring the width of the head.

It should be borne in mind that in the conditions of Northern Eurasia, forests that have died from the silkworm are poorly restored. Caterpillars destroy the undergrowth along with the forest stand, and only a decade later, a small undergrowth of deciduous species may appear. In old foci, conifers appear only 30-40 years after the drying of forest stands, and not everywhere and not always.

The main reason for the lack of natural renewal in silkworms is a dramatic ecological transformation. plant communities. During the mass reproduction of the silkworm in 3-4 weeks, up to 30 t/ha of eaten fragments of needles, excrement and corpses of caterpillars enter the litter and soil. Literally within one season, all the needles in the plantation are processed by caterpillars and enter the soil. This litter contains a significant amount organic matter- favorable food for soil bacteria and fungi, the activity of which is significantly activated after the mass reproduction of the silkworm.

This is also facilitated by an increase in soil temperature and moisture, since neither sunlight nor rainfall is trapped by the tree canopy anymore. In fact, the mass reproduction of the silkworm contributes to a more intensive course of the biological cycle as a result of the rapid release of significant the amount of matter and energy contained in the forest floor.

The soil in silkworms becomes more fertile. A light-loving grass cover and undergrowth rapidly develops on it, intensive turfing and often swamping occur. As a result, heavily disturbed stands are replaced by non-forest ecosystems. Therefore, the restoration of plantations close to the original ones is delayed for an indefinite period, but not less than 200 years (Soldatov et al., 2000).

Outbreaks of mass reproduction of the Siberian silkworm in the forests of the Ural Federal District

In general, despite the large number of works on the ecology of the Siberian silkworm in the 50-60s, many features of the ecology of the Trans-Ural population under the conditions of global anthropogenic impact remain unexplored.

Outbreaks of mass reproduction of the Siberian silkworm in the larch forests of the Cis-Urals have been observed since 1900 [Khanislamov, Yafaeva, 1962]. y.y. First outbreak in the forests Sverdlovsk region discovered in 1955 on the territory of the Tavdinsky and Turinsky forestries. The total area of ​​outbreaks was 21,000 ha and 1,600 ha, respectively. On the territory of the Tavdinsky forestry, large foci were formed earlier. It is noteworthy that these forestry enterprises have been the place of intensive timber harvesting for many decades. Therefore, coniferous forests have undergone anthropogenic transformation and currently have an admixture of secondary birch forest with pine, spruce and fir in the undergrowth. It should be noted that a new outbreak (1988-1992) in the Sverdlovsk region was registered in other forestries. To the greatest extent, it was formed in the forests of the Taborinsky district. The total area of ​​the outbreaks was 862 ha, some outbreaks were also observed during aerial surveillance in the Garinsky district.

Studies have shown that on 50% of the areas affected by outbreaks in 1988-1992, the main forest-forming species is birch with fir and spruce in the undergrowth (Koltunov, 1996, Koltunov et al., 1997). Fir undergrowth strongly defoliated by the Siberian silkworm and mostly shrunken. As a result, significant damage was caused to the development of coniferous economy in these forestries. The primary centers of mass reproduction of the Siberian silkworm appeared in 1988 in plantations with fir undergrowth. In 1993, the outbreak completely died out. On the territory of KHMAO-YUGRA, the outbreak of mass reproduction died out in 1992. In some quarters, defoliation by the Siberian silkworm of spruce was observed, as a result of which it also quickly dried out. As studies in the foci of this phytophage during the outbreak showed, the development of the Trans-Ural population occurs mainly according to a two-year cycle. In general, studies have shown that the topography of broad silkworm foci in the coniferous forests of the Sverdlovsk region coincides with forest areas disturbed by anthropogenic impact.

On the territory of the Khanty-Mansiysk Autonomous Okrug, an outbreak of mass reproduction of the Siberian silkworm was found in the territories of the Mezhdurechensky, Uraisky, Tobolsky, Vagaysky and Dubrovinsky forestry enterprises. The total area of ​​outbreaks was 53,000 ha. We carried out the most detailed studies in the centers of mass reproduction of the Siberian silkworm in the Mezhdurechensk forestry.

Over the past 20 years, the most intensive industrial logging has taken place on the territory of Yuzhno-Kondinsky LPH. As the results showed, the spatial structure of the centers of mass reproduction of the Siberian silkworm in this forestry clearly does not coincide with the forests subjected to the most intense anthropogenic impact (first of all, cutting down). The largest outbreaks (in the western part of the forestry enterprise) are completely unaffected by anthropogenic impact. Felling in the forests before the outbreak was not carried out. We also did not find any other types of anthropogenic impact. An analysis of the forest inventory parameters of forest stands in this group of foci showed that these forests have the usual productivity for this type of forest growth conditions and are not weakened. At the same time, cuttings are observed next to other, smaller foci, and in some cases, fires. Some of the centers with a strong defoliation of crowns of forest stands were previously cut down.

As the results showed, the anthropogenic impact in the dark coniferous lowland forests of the Trans-Urals is not key factor formation of centers of mass reproduction of the Siberian silkworm, although its contribution is undoubted. Under conditions of moderate anthropogenic impact, the main factor in the organization spatial structure foci are forest conditions in ecotopes and features of the microrelief. Thus, the largest foci adjoin river beds and places with microelevations, which is known earlier [Kolomiets, 1960, 1962; Ivliev, 1960]. Especially important fact is that the forests in the areas of outbreaks were not noticeably weakened under the influence of anthropogenic factors. The level of anthropogenic transformation of these forests was extremely insignificant, no higher than stage 1 in some ecotopes (5-10% of forests). As the geobotanical analysis of the grass layer showed, the grass cover in these forests is not changed.

Thus, to the greatest extent, these forests are affected only by the proximity to clearcuts (changes in light and wind conditions) and, to a lesser extent, by fellings carried out several decades ago in some of them.

An analysis of the radial growth of trees in the foci and beyond their boundaries confirms our conclusion about the preservation of the stability of forests in general, which have undergone defoliation. We associate the reduced radial growth of trees in the foci with the adaptive response of forest stands to forest vegetation | conditions, but not with their weakening, since we did not find these differences in last years and for 50 years or more.

A characteristic feature of the dynamics of stand defoliation during the outbreak in the lowland forests of the Trans-Urals was a clear preference for defoliation of fir in the undergrowth at the beginning of the outbreak, then fir in the main layer, and later spruce and stone pine. Pine defoliated very weakly. Therefore, no foci were formed in pure pine forests. The study of the Trans-Ural population of the Siberian silkworm in the outbreaks showed that in the eruptive phase and before the outbreak faded, the adult hatching rate was very low and ranged from 2 to 30%, averaging 9.16%.

Most of the pupae population dies. The most significant percentage of the population dies from infectious diseases (bacteriosis and granulosa virus). Death from these causes ranges from 29.0 to 64.0%, on average, 47.7%. Bacterial infections accounted for the main percentage of the causes of death from this group of diseases. Viral infections were much less common. It should also be noted that the microscopic analysis of the dead caterpillars in the outbreaks both in Sverdlovsk and Khanty-Mansiysk Autonomous Okrugs convincingly showed that the attenuation of outbreaks was not accompanied by a viral epizootic (granulosis virus).

Our results are in good agreement with the data of other researchers on other populations of the Siberian silkworm [Khanislamov, Yafaeva, 1958; Boldaruev, 1960, 1968; Ivliev, 1960; Rozhkov, 1965].

During the period of attenuation of the outbreak of mass reproduction of the Siberian silkworm in the forests of the Khanty-Mansi Autonomous Okrug, up to 30 caterpillars per 1 m 2 were found in the litter, which died from infectious diseases.

As the results showed interesting feature In the plain dark coniferous forests of the Khanty-Mansiysk Autonomous Okrug, the forest stands that dried up after defoliation by the Siberian silkworm in the flat dark coniferous forests of the Khanty-Mansiysk Autonomous Okrug were almost completely absent from xylophagous insects within 1-2 years after drying, although in the forests undamaged by the Siberian silkworm, xylophagous colonization of drying stands and individual trees is observed .

At the same time, it should be noted that the supply of xylophages in the areas of outbreaks is sufficient. In addition, at the shift plots and at the stock depots in Yuzhno-Kondinsky LPH, the whips left without treatment are quickly populated by xylophagous insects. We attribute the slowdown in the colonization of shrunken forest stands by xylophages after their defoliation by the Siberian silkworm to a greater extent with the increased moisture content of the wood. This, in our opinion, was due to the active transport of water by the root system of trees after crown defoliation against the background of the cessation of transpiration due to the absence of needles.

Studies in the centers of mass reproduction of the Siberian silkworm in the Trans-Urals showed that the last outbreak of this phytophage in the dark coniferous forests of the plain Trans-Urals was observed 33 years ago. It can be assumed that the cyclicity of outbreaks of this phytophage on the western border of the range is closely related to the periodicity of the most severe droughts in 1955 and 1986. The most severe drought (in 1955) was also accompanied by a larger area of ​​foci of this phytophage in the Trans-Urals.

Previously, there were no outbreaks of the Siberian silkworm in the Kondinsky forestry enterprise. The dendrochronological analysis of fir and spruce cores (for the last 100-120 years), carried out by us, showed that forest stands, both in the focus and beyond its borders, had not previously been subjected to noticeable defoliation. Based on our results, we can assume that there is a gradual penetration of the Siberian silkworm to the north and the emergence of outbreaks of mass reproduction in these habitats, which were not previously observed there. This is probably due to the gradual warming of the climate.

The relationship between the spatial structure of foci and anthropogenic impact on forest biogeocenoses is not convincingly traced. Foci were identified both in forest areas where active logging was carried out, and in forests completely unaffected by logging, which are significantly removed from roads, winter roads and settlements.

Based on the obtained results, it was established that under the conditions of anthropogenic transformation of the dark coniferous forests of the Trans-Urals, the largest foci of the Siberian silkworm can appear both in completely undisturbed forests and in forests exposed to anthropogenic factors.

A comparative analysis of the spatiotemporal structure of the foci during the last two outbreaks shows that the foci of mass reproduction each time are formed in different ecotopes and do not coincide spatially at all. As the results of the research showed, the first outbreaks in each of the surveyed forestries appeared in 1988 simultaneously with other outbreaks in the more southern regions of the Tyumen region. This excludes the possibility their emergence by migration from the southern part of the range. Probably, the population in the phase of depression was also in the northern part of the range of this population.

On the western border of the range of this phytophage, outbreaks are of a fast-moving character. This is well explained by the narrowness of the time interval of the climatic optimum during the drought period. Taking this into account, as well as the presence of a two-year cycle in Siberian silkworm caterpillars, this gives good prospects for reducing the economic damage from outbreaks through the use of active measures in the period immediately before the eruptive phase of the outbreak. Sustaining a high outbreak potential is possible only during this narrow period of drought. Therefore, the treatment of foci during this period will eliminate the likelihood of the formation of large repeated steps.

As shown by the results of a comparative analysis of the forest taxation parameters of 50 sample plots laid in the centers of mass reproduction of the Trans-Ural population of the Siberian silkworm in the Taborinsky forestry enterprise of the Sverdlovsk region, the centers were formed in forest stands with different density: from 0.5 to 1.0, on average - 0, 8 (Tables 3.1,3.2). Correlation analysis showed that the areas of the foci positively correlated with the quality class (R=0.541) (with the worst growth conditions), average height (R=0.54) and negatively correlated with fullness (R=-0.54).

However, he draws attention to the fact that out of 50 trial plots, only 36% of the plots with a density lower than 0.8 formed centers of mass reproduction of the Trans-Ural population of the Siberian silkworm, while in the vast majority of trial plots the density was 0.8 and higher. The average level of defoliation of more low-density forest stands is, on average, 54.5%, while for high-density stands (with a density equal to 0.8 or more) - 70.1%, but the differences were not statistically significant. This probably indicates that the level of defoliation is influenced by a complex of other factors, which is common for a group of forest stands. The contribution of this group of factors to the level of entomoresistance of forest stands was significantly higher than the influence of the density of forest stands.

Studies have shown that this factor is the soil-edaphic conditions in ecotopes. Thus, all stands on the test plots, which were located on ridges, in drier habitats, were defoliated most strongly, compared with stands on the flat parts of the relief, or microdepressions. Correlation analysis of the degree of defoliation with other forest inventory parameters also did not reveal a statistically worthy of its relationship with the quality class (r = 0.285). Nevertheless, average level defoliation of the lowest quality forest stands (with a class of quality: 4-5 A) was 45.55%, while in the most high quality - 68.33%. The differences are statistically significant (at P=0.01). The absence of a significant linear correlation was also probably due to the strong dominance of the factor of soil and edaphic conditions. This is accompanied by a strong defoliation of forest stands, which differ significantly in quality class. It is also impossible to exclude the possible influence of the factor of local migration of caterpillars from completely defoliated high quality forest stands to nearby low quality stands. Although it should be noted that caterpillars in the crown were recorded by us in both groups of forest stands. Therefore, local migration in any case was not the main reason for the strong defoliation of low quality forest stands.

Analysis of the results shows that in the conditions of flat dark coniferous forests of the Sverdlovsk region. there is a certain tendency to the predominant formation of foci with the strongest crown defoliation in stands with more high class quality. But there is also no noticeable avoidance of low quality forest stands. Foci with varying degrees of crown defoliation occur in forest stands with different quality classes. But the lowest insect resistance and strong defoliation are characteristic of plantations with the highest quality class. Taking into account the close relationship between the degree of defoliation and the level of resistance of forest stands at the same initial population density, it can be assumed that under these forest conditions, as a result of the impact of the abiotic stress factor (drought), the resistance of forest stands with a higher bonitet class decreases more than that of low-bonitet forest stands, which is accompanied by higher crown defoliation. high quality forest stands.

An analysis of the features of the composition of forest stands in the centers of mass reproduction of the Siberian silkworm in the Sverdlovsk region made it possible to identify two main types of strategy for the formation of centers in relation to the composition of forest stands.

1 type of strategy. Foci occur in the main layer of the forest. These forest stands are most often located on the manes of elevated parts of the relief in drier types of forest. The centers with the most significant defoliation of forest stands are formed in spruce-fir and fir-spruce stands with an admixture of birch (6P2E2B, 5E2P2B). The undergrowth contains fir, which is the first to undergo severe defoliation. In foci of this type, strong defoliation is always observed. The foci, as a rule, are of a concentrated type with a well-defined border. Surveys in the foci have shown that under these conditions, which are optimal for an outbreak, the predominant rock composition is not critical and can vary within fairly wide limits. Nevertheless, in forests with a predominance of fir in the main layer and undergrowth, the formation of foci with severe defoliation is most likely. It can be assumed that under optimal soil and edaphic conditions general level drops in resistance and fir and spruce are higher than the level of differences in resistance between these species in less optimal habitats. According to the composition of the forest stand in these foci, there were no plantations with a predominance of fir at all, but there is a spruce forest with fir and a birch forest with fir undergrowth.

It should be noted that, in foci of this type in the Sverdlovsk oblast, there is usually a rapid colonization of dried forest stands by xylophagous insects, while in the foci of the Siberian silkworm in the forests of the Khanty-Mansiysk Autonomous Okrug, as mentioned above, the colonization of dead stands by xylophagous insects almost did not occur.

2 type of strategy. The foci do not appear in the main type of forest, but in the undergrowth. This is typical for areas of forest that have been cut down. In this type of forest, the occurrence of foci occurs regardless of the species composition of the main layer. This is due to the fact that in many types of forest that have undergone heavy felling, there is an abundant undergrowth of fir, which is completely defoliated and dries out. Often the main layer in these types of forest stands is birch, less often pine and other species. Consequently, these types of forests are intermediate in the dynamics of succession, when the change of species occurs most often through birch (Kolesnikov, 1961, 1973).

Studies have shown that in these types of forests, foci are formed under a wider range of forest-vegetation and soil-edaphic conditions. Foci of this type are often found not on elevated, but on plain elements of the relief, but not excessively moistened.

In foci with severe defoliation in the forests of the Sverdlovsk region. aspen is very rare in the composition of the main layer, as it is an indicator of wet habitats. However, in individual foci with severe defoliation, it is still found in small quantities. Usually these are foci formed in the flat part of the relief, with separate depressions. As is known, such forest stands begin to be damaged by the Siberian silkworm after a long drought, which reduces soil moisture (Kolomiets, 1958, 1962).

The last outbreak of mass reproduction of the Siberian silkworm occurred in 1999 and continued until 2007 (Fig. 3.3). It was the largest outbreak in Russia in the last 30 years.

The main area was made up of centers of mass reproduction in Siberia and the Far East. In the Trans-Urals, it was, on the contrary, very weak. In the forests of the Chelyabinsk region. areas of outbreaks in 2006 and 2007 amounted to 116 and 115 ha, respectively, in the forests of the Tyumen region. in 2005 their total area was 200 ha, in the next 2 years they were not recorded. In the forests of the Sverdlovsk region. she was absent.

For the first time, we have studied the features of the development of outbreaks of mass reproduction in the forests of the Sverdlovsk region. and the Khanty-Mansiysk Autonomous Okrug (KhMAO-UGRA).

In general, the results showed a very close similarity of the forest conditions of the preferred ecotopes in the Trans-Urals and West Siberian populations of the Siberian silkworm. This is due to the close similarity of the habitat conditions of these populations in swampy lowland dark coniferous forests.

It has been established that under the conditions of anthropogenic transformation of the dark coniferous forests of the Trans-Urals, the Siberian silkworm can form large foci both in forests disturbed by anthropogenic factors and in completely undisturbed forests. Studies have shown that a moderate level of anthropogenic transformation of the lowland dark coniferous forests of the Trans-Urals is not the dominant factor in the occurrence of foci. The rank of this factor is approximately similar to other natural preference factors, the main of which is the microrelief and relatively dry habitats.

In the western part of the range of the Siberian silkworm, outbreaks are of a fast-moving character. There are predominantly concentrated foci. The nature of the spatial structure of the primary foci suggests that they arose in a non-migratory way, and the Siberian silkworm is found in the area of ​​outbreaks and during the period of depression. The formation of foci with strong defoliation is observed in forests with a wide range of density and quality classes in KhMAO-Yugra - in fir-spruce forests, in the Sverdlovsk region - in derived birch forests with fir undergrowth and spruce-fir forests.

The dendrochronological analysis of fir and spruce cores (for the last 100-120 years), carried out by us, showed that forest stands, both in the focus and beyond its borders, had not previously been subjected to noticeable defoliation. Consequently, earlier there were no outbreaks of mass reproduction of the Siberian silkworm in the Kondinsky forestry of the Khanty-Mansiysk Autonomous Okrug. On the basis of our results, we can assume that there is a gradual penetration of the Siberian silkworm to the north by migration and the emergence of outbreaks of mass reproduction in these habitats, which were not previously observed there. This is probably due to the gradual warming of the climate.

It has been established that the reduced average annual radial growth of spruce and fir in the centers of mass reproduction of the Siberian silkworm is not a consequence of the weakening of forests in recent years, but represents the norm of the reaction to relatively dry growth conditions on ridges and microelevations of the relief, and the difference in radial growth persists for many decades. .

Despite the obvious increase in the scale and level of anthropogenic impact on the plain dark coniferous forests of the Trans-Urals and Khanty-Mansi Autonomous Okrug-Yugra, the frequency of outbreaks of mass reproduction of the Siberian silkworm has not changed.

The Siberian silkworm in the Trans-Urals and the Western part of Western Siberia is still a very dangerous pest, causing significant environmental and economic damage to the forestry of the region. Therefore, we consider it necessary to strengthen the monitoring of the Trans-Ural population of the Siberian silkworm.

It is clear that the basis successful fight with the Siberian silkworm is the periodic monitoring of the abundance of this phytophage in the reserves. Due to the fact that the occurrence of outbreaks of mass reproduction of the Siberian silkworm is closely synchronized with spring-summer droughts, surveillance during this period must be significantly strengthened.

It is necessary to analyze the state and size of the population in other parts of the forest.

Control measures should be planned for the start of an outbreak when more than 30% defoliation in fir and spruce, cedar pine, or severe (70%) larch defoliation is predicted.

As a rule, aerial treatment of forests with insecticides is carried out. The most promising biological drug to date is lepidocide.