Invasion of the winged. How to explain the outbreak of mass reproduction of the silkworm?

The residents of the European part of Russia will remember the past week as a grandiose invasion of grayish-white butterflies that flooded the streets and squares of cities. Moths stick around poles and trees, hang on walls and window sills of houses, hit windows and fly into apartments. In the Ulyanovsk region, pests have destroyed more than 2 thousand ha of forests. Also, butterflies of the gypsy moth (this is the name of this species) were seen in the Vladimir, Ryazan and Moscow regions, Tatarstan and Bashkortostan, the republics of the North Caucasus and the Urals.

With the help of Head of the Forest Protection Laboratory from invasive and quarantine organisms of the All-Russian Research Institute of Forestry and mechanization of forestry, Yuri Gninenko aif.ru figured out what this phenomenon was and and why it is dangerous .

Where did these butterflies come from?

Gypsy moth — widespread species. It lives throughout Europe and Siberia, the Caucasus, Asia Minor, Japan and North America.

 He is not an invasive (alien) species for our country. This is our aborigine, which lives in deciduous forests from Kaliningrad to Vladivostok, — explains Yuri Gninenko. — Silkworms give birth once a year. Eggs overwinter, as a rule, in trees, caterpillars appear in spring, and at the end of July – At the beginning of August, butterflies are already flying.

The picture that we are seeing now in the Moscow region (in Shatura, Lukhovitsy, Egorievsk, Elektrostal) and other regions of the European part of Russia, — a consequence of another outbreak of mass reproduction of the gypsy moth. Similar appearances of butterflies in cities took place in 1892 and 1957, when even the walls of the Moscow Kremlin were lined with silkworm masonry. And now it happened again.

In fact, usually outbursts of mass reproduction of a non-greenhouse are observed once every 10-12 years. But there are cases with an interval of 65 years, when there is a massive flight of butterflies into settlements. Why this doesn't happen in every flash, but only with such a large interval, nobody knows».

Perhaps, the expert believes, favorable conditions have developed — temperature and & nbsp; good nutrition. This led to a sharp increase in the number of insects and their distribution over long distances. In the electric steel, grayish-white butterflies covered the entire area in front of the Park Plaza shopping and entertainment center. (his employees even called the Ministry of Emergency Situations). But especially a lot of them seen in Ulyanovsk region. Residents of the region share photos and videos on social networks and admit that they have never seen such an invasion of insects.

Why are they dangerous?

During outbreaks of mass reproduction, the gypsy moth eats deciduous forests and gardens. Caterpillars do this. They damage 300 species of woody plants, but are especially fond of birch, oak, linden, willow, and aspen. From fruit — apple, pear, plum.

“For people, these insects do not pose a danger. They cannot bite a person, damage buildings — too. But there there are people who        can cause allergies, so they should be careful  — Yuriy Gninenko pays attention.

How to deal with them?

According to the expert, it is necessary to treat forests with pesticides or bacterial preparations. And this year, such procedures were carried out and gave a good result: over 90% of the caterpillars died. “But” there are places where such processing cannot be carried out due to existing prohibitions. They are located on & nbsp; various kinds of specially protected natural areas (SPNA), & nbsp; & mdash;  he says. — In my opinion, this is a very outdated approach. Now there are already technologies that can be applied in such territories. Otherwise, as we see, the remaining caterpillars eat the forests, and then give a massive outbreak of butterflies».

After that, & nbsp; butterflies will lay their eggs, it is necessary to scrape off and destroy all the egg-laying that can be found in & nbsp; cities. You can't just throw away the eggs — in the spring, caterpillars will hatch out of them anyway. It is best to burn them or pour bleach on them.

The Ministry of Natural Resources of the Ulyanovsk Region, where the gypsy moth has destroyed more than 2 thousand ha of forests, is already implementing a plan to combat the pest: installing pheromone traps , keep records of insects by oviposition, after which they will begin to destroy them.

In addition, after such outbreaks of mass reproduction of the gypsy moth, its population is exterminated by entomophages — viruses, parasites and  predators, which include, for example, the odorous beetle. After that, the number of silkworms decreases naturally.

What other insects threaten our forests?

There are a great many of them. Damage to foliage or needles is caused by caterpillars of Lepidoptera (butterflies), larvae of Hymenoptera (sawflies), leaf beetles and other insects. During outbreaks of mass reproduction, their colonies eat tree crowns, causing subsequent drying out. Dark coniferous breeds are most sensitive to the activity of leaf-eating pests — spruce, fir, cedar pine.

For plant trunks, the threat is posed by beetles (gold beetles, bark beetles, weevils, barbels), hymenoptera (horntails, xyphidria), lepidoptera (glass butterflies, wood borers). Some destroy the bark, others leave wormholes, including deep ones, which significantly devalue the wood. And the third group of insects damages the roots. These include arthropods that live in the soil. Particularly dangerous are the larvae of lamellar beetles, wireworms (click beetles), dark beetles (false wireworms). Young plantations are especially affected by root pests.

“The most dangerous enemy of Russian forests is the Siberian cocoon (silkworm). It destroys the coniferous forests of Siberia, also from time to time giving outbreaks of mass reproduction, — says Yuri Gninenko. — A on the European part of the country, the red pine sawfly is very harmful to pine plantations. In addition, now such a pest as the eastern May beetle is showing itself more and more.

In recent years, a lot of alien (invasive) insect species have penetrated Russian forests. If in the middle of the last century in our forests were harmed mainly by the American white butterfly and several species of sucking insects, then in the 21st century the penetration of pests has noticeably increased.

& laquo; in & nbsp; Moscow and & nbsp; around it, a ash, a narrow -colored emerald gold, & nbsp; & mdash; gives an example of a specialist. — They came here from the forests of the Far East, where it lives, without posing any threat to local ash species. There, it harms only Pennsylvania ash in urban landscaping. In  the European same part of Russia, it also harms the native species — common ash. This has become a significant threat to both landscaping and the country's forestry. Zlatka began to expand its range and in some areas it has long gone beyond the boundaries of the Moscow region. Now it has already reached the floodplain of the Volga in Volgograd.

In the southern regions of the country, the oak lace bug is very harmful to the oak. And earlier, the boxwood moth destroyed all the boxwood trees in the North Caucasus. So there are a lot of examples of the exceptional harm of alien species of insects.

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