"It is more important to investigate the number of Dendrolimus punctatus on a tree than to eliminate them." Yan Guozeng, chief engineer of Beijing Forestry Protection Station, told the reporter. It turns out that in order to reduce the environmental damage caused by spraying pesticides, Beijing has adopted biological control methods in pest control. The premise of biological control is to predict the severity of pests. Yan Guozeng said: "We even use' biological missiles' to deal with pests-using Trichogramma carrying viruses to spread' plague' among pests."
The reporter learned from the forestry protection station that with this "funnel" device, coupled with the eight strange tricks of biological pest control introduced by Beijing in the past two years, the trees in Beijing have been fully protected.
"Funnel" Device Works Miracles
The caterpillar plays "slick" to avoid "golden eye"
The principle of "funnel" device is actually very simple. It ties a "funnel" with plastic film on the trunk of Pinus tabulaeformis, and stops it on the "only way" for Dendrolimus tabulaeformis to go down the mountain and overwinter in autumn, and investigates the occurrence of Dendrolimus tabulaeformis larvae, so that the accuracy of forecasting the occurrence of Dendrolimus tabulaeformis can reach over 95%. In the past, the accuracy of traditional survey methods was only 20%.
Pinus tabulaeformis is a common tree species in Beijing, and Dendrolimus punctatus is the most harmful to its growth. The tender pine needles in May are delicious food of Dendrolimus punctatus, which is different from the broad-leaved trees only affected by pests. Eating pine needles by caterpillars is equivalent to killing Chinese pine.
Dendrolimus punctatus is the larva of a moth that lays eggs on pine needles. In autumn, the caterpillar will climb down the tree and spend the winter in the grass, and wait until the next spring to "harm" the Chinese pine.
The traditional investigation method is that when Dendrolimus punctatus overwinters under the tree, forestry workers rummage under the tree. However, the caterpillar is very cunning. Some of them hide under weeds and litter under trees in winter, while others hide in cracks in bark. Although the staff hate that they can't all have "golden eyes", there will still be many "bugs that escape the net".
"In the past, we have been doing research under the tree, but next spring we will all find that we have been fooled. In the second year, there were many more Dendrolimus punctatus on the trees than in the first year. " Wang Xiaojun said. So he began to think, "What should be done to cure them?" !
Researchers can easily calculate the number of caterpillars by "waiting for worms"
"The trunk of Pinus tabulaeformis is the only way for caterpillars to get down the tree. As long as a trap is set on the trunk, the caterpillar has nowhere to escape. " Wang Xiaojun said. At first, his idea was to tie the bottom of a hard plastic film on the trunk and let it face upwards to form a "funnel" shape to prevent caterpillars from crossing.
However, he just tied the lower end of the plastic film to the trunk with a thin iron wire, and when a gust of wind blew, the plastic film stuck to the trunk with the wind. "What if I put a skeleton on the funnel?" Wang Xiaojun continued to "improve" his funnel. In this way, no matter how the wind blows, it can't change the direction of the funnel mouth, and the funnel stubbornly opens its mouth to meet the caterpillar's "capture".
As the temperature dropped, Dendrolimus tabulaeformis began to overwinter. But at this time, there is a "funnel" waiting for them in the middle of the trunk of Pinus tabulaeformis. The Dendrolimus punctatus, which fell into the "trap", was caught and twisted to death by researchers before it could climb the tree to hide. Generally, it lasts about half a month, and the Dendrolimus punctatus on the tree completes their "migration". Researchers only need to "wait for insects"-accumulate the number of caterpillars under the tree every day, and they can measure the caterpillar base of this Chinese pine.
Eight Skills of Biological Pest Control
The first trick: biological missiles go straight to the nest of pests
It's not just Dendrolimus punctatus that harms Beijing's forests. Yan Guozeng introduced that, for example, Zhou moths specifically harm poplar leaves, and two kinds of Chinese fir beetles suck the juice of Chinese fir trees. For all kinds of pests, forestry workers have developed various biological control methods, and even used "biological missiles".
If Trichogramma dendrolimi, a parasitic wasp of Dendrolimus punctatus, is allowed to carry a virus that can kill Dendrolimus punctatus and spread among Dendrolimus punctatus populations, Trichogramma dendrolimi carrying the virus will become a special "biological missile". When it parasitizes Dendrolimus punctatus, the diseased Dendrolimus punctatus can set off a "plague" in the whole population.
The second measure: artificially raise gray magpies to eat insects.
Yan Guozeng introduced that if the number of Dendrolimus punctatus on a Chinese pine tree is less than five, it is a mild hazard, and this situation can be ignored. However, if the number exceeds 6, measures need to be taken to prevent it. If it exceeds 20, it is a serious hazard. "If there is moderate damage, we will give it a' natural enemy'." Yan Guozeng said.
Gray magpie is widely used as the natural enemy of Dendrolimus punctatus. Wang Xiaojun introduced that Miyun Reservoir Management Office, surrounded by oil pine trees, specially used domesticated grey magpies as the "guardians" of Chinese pine.
"We introduce young magpies from other places and domesticate them artificially-whenever we want to feed magpies, the breeder will blow the whistle. When magpies grow up, they are put into Chinese pine forests to prey on caterpillars. As soon as the work is over, all the magpies will fly back. "
Due to the high cost of artificial breeding of grey magpies, after successful domestication, Miyun Reservoir Management Office will release the grey magpies into nature and let them reproduce on their own. Up to now, more than 2,000 grey magpies have been released to control pests such as Dendrolimus punctatus around Miyun Reservoir. And a grey magpie can kill 400 Dendrolimus punctatus every day.
The third measure: bionic preparation to end the life of pests
If the investigation base of Dendrolimus punctatus has reached serious pests, it is the best way to treat Dendrolimus punctatus by spraying bionic chemicals by plane at this time.
After all the Dendrolimus punctatus trees were planted in early April, the plane began to spray bionic chemicals. After pine needles stained with bionics are eaten by Dendrolimus punctatus, the bionics will destroy the enzymes that control the growth of the "skin" (the outer skin of the caterpillar) in the caterpillar. Dendrolimus punctatus undergoes seven molts from egg to adult, and its growth process is actually a continuous molting process. After eating pine needles soaked in bionic preparation, the caterpillar will not shed its skin again, and the life of the worm will be over.
Chief engineer Yan Guozeng introduced that due to long-term adherence to biological control of Dendrolimus punctatus, the area of damaged Pinus tabulaeformis forest in Beijing has been reduced from 6,543,800 mu to 30,000 mu, mainly distributed in Pinggu, Huairou, Changping, Miyun and Mentougou.
The fourth measure: copy the virus "fight poison with poison"
In the virus laboratory of Biological Control Center of Beijing Forestry Bureau, the staff also developed gypsy moth virus and Popeye moth virus to control these two pests.
Different from "biological missiles", these viruses are extracted from dead insects, inoculated into artificially propagated healthy adult gypsy moths, and then toxins are extracted from the body fluids of a large number of infected pests.
After the toxin is diluted, the staff will spray it by plane. This method can not only kill insects in a large area, but also has no harm to the environment.
Yan Guozeng introduced that toxins extracted from body fluids of pests and diseases have the characteristics of "specificity", which can cause "epidemic situation" among pests similar to pests and diseases, and have no harm to other insects.
The fifth measure: artificially raise swollen-legged bees to eat longicorn larvae.
There is a small bee with thick hind legs, which can absorb nutrients from the larvae of Monochamus alternatus, which are harmful to trees, and thus kill Monochamus alternatus. Researchers call this little bee "swollen-legged bee".
The larvae of Anoplophora longicorn are tender and much larger than the "swollen-legged bee". However, as long as it is pricked with "anesthetic" by "swollen-legged bee", the larvae of longicorn beetles will be easily caught.
Hou, an assistant engineer at the Biological Control Center, said that it was purely accidental to find that "swollen-legged bees" could kill the larvae of longicorn beetles. In the 1980s, two Chinese fir trees on the Western Hills of Beijing were harmed by longicorn beetles. Groups of longicorn beetles got into the trunk and ate the tree into a hole.
The staff of the center cut down the hollow trees eaten by longicorn beetles and took them back to the research center. After research, I was surprised to find that this kind of bee with thick hind legs can absorb the nutrition of longicorn larvae through "parasitism" and make them "die young" "So, we will breed this' swollen-legged bee' on a large scale and send it to the disaster-stricken areas of the longicorn beetle disaster."
The sixth measure: 500 million "Zhou's biting wasps" went into battle together.
The natural enemy of moths that harms a large number of trees in this city is "Zhou's biting bee". This kind of bee is only 1 mm long, but it has strong flying ability and parasitic ability, and can keenly find pests hiding in various hidden places to pupate. Can be used for preventing and controlling LEPIDOPTERA pests, such as Popeye, Poplar Moth, Willow Moth, Ulmus pumila, Marsupial Moth, etc.
Because of the "appetite" of "Zhou's biting wasps", Beijing forestry department has released 500 million "Zhou's biting wasps" in Daxing, Tongzhou, Pinggu, Shunyi, Huairou, Changping, Fangshan and other 12 suburban counties. During the pupation of moths, the staff will fix the "Zhou's biting wasp" parasitic in silkworm pupae on the tree and release the wasp. "Zhou Bite the Wasp" was released to nature, like a flock of horses heading straight for the moth nest, killing moths that are still pupating.
The seventh trick: ladybugs eat up the pests in Zizhuyuan.
Ladybugs in colorful clothes are natural enemies of pests-aphids. The green bamboo in Zizhuyuan was once troubled by aphids, "depressed" and withered leaves, and won the victory by relying on the natural enemy ladybug of aphids.
According to Hou of the Biological Control Center, last year, after learning that the green bamboos in Zizhuyuan Park were suffering from aphids, the Biological Control Center urgently allocated 50,000 ladybugs to Zizhuyuan. The easiest way for ladybugs to deal with aphids is to eat with their mouths open. Aphids with thin skin and juicy juice are undoubtedly a good meal for ladybugs. In just over a month, bamboo has grown new leaves.
Eighth measure: plastic "circle" to prevent pests from climbing trees.
Another way to prevent insects is to wrap a tape about 20 cm wide in the middle of the trunk, just like putting a plastic "ring" on the tree.
This method is often used to control grass scales. The inchworm can be regarded as an "old-timer" among pests. It is the earliest pest in Beijing, which not only harms trees and fruit trees, but also seriously disturbs people.
According to the observation for many years, grasshoppers began to move in the middle and late June of 65438+ 10, and moved up and down the trees with the daily temperature change. By February and March, larvae will also enter residential areas and houses, interfering with the normal life of residents.
The method of controlling this kind of insect is relatively simple. Before grass grows on the trees in the middle and late June of 5438+ 10 every year, the rough skin of the old trunk is scraped off and wrapped with 20 cm wide adhesive tape or plastic film. The smooth plastic film makes it difficult for grasshoppers to crawl, and most insects will gather under the plastic film. Every three to five days, when they gather to a certain scale, they can be rubbed manually 1 time or scalded with boiling water, which will have a good control effect.