In nature's food chain, most creatures have their own natural enemies, and they are mutually exclusive and maintain ecological balance. This wonderful relationship is being continuously used in plant protection today, especially in agricultural plant protection, where scientists use the natural enemies of agricultural pests to prevent and control major pests in agricultural production, or to prevent and control invasive pests from outside, which is a kind of biological control - natural enemy control.
Located outside the North Fifth Ring Road in Beijing, the Institute of Plant Protection of the Chinese Academy of Agricultural Sciences has a "National Natural Enemies and Other Insect Resource Data Center" (referred to as the Natural Enemies Center). The center has set up more than 100 stations across the country to conduct long-term monitoring and investigation of resource background, distribution and dynamics of natural enemies insects, beneficial mites and spiders on the mainland, including insects that provide protein sources, evaluate and screen out the dominant natural enemy species, and provide basic data and services for the safe production of agricultural products and government decision-making.
In the Institute of Plant Protection of the Chinese Academy of Agricultural Sciences, there is a "National Natural Enemy and Other Insect Resource Data Center" (referred to as the Natural Enemy Center). Beijing News reporter Wang Ying photographed
"Treating insects with insects", using the original resources of nature to protect the fruits of human labor, and providing us with food that is more in line with the concept of ecological development and green health, is the original intention of natural enemy prevention and control. On August 15, a reporter from the Beijing News visited the Center for Natural Enemies to find the stories that happened here and explore the history of the struggle between natural enemies and pests.
Pictures of insects are displayed on the propaganda wall. Beijing News reporter Wang Ying photographed
Use natural resources to protect plants
It has just cooled into autumn, and the red spiders that have experienced the heat wave are ready to move.
The trees in the yard of the plant protection institute are verdant, however, the leaves on several peach trees appear to be a little abnormal, the leaf surface is covered with white spots, and there are many small red spots on the back, these red dots are very small, they are leaf mites, commonly known as red spiders, is a common agricultural pest, the body length is only about 0.5 mm, almost harming most of the fruit trees, vegetables, and even many food crops, the white spots on the leaf surface are caused by them after sucking the branches and leaves.
The history of human farming is also a history of fighting pests and diseases, and for thousands of years, people have come up with all kinds of ways to protect crops in farmland and protect our food sources.
Since modernization, with the development of the chemical industry, efficient and rapid chemical pesticides have once become the main tool of plant protection. However, with the passage of time, the side effects of chemical pesticides have become increasingly apparent, and its threat to food safety and the impact on the ecological environment have attracted more and more attention. At the same time, due to drug resistance, the control effect of chemical pesticides on many diseases and insect pests is gradually weakening.
Leaf mites are one of them, and in recent decades there have been fewer ways to deal with these tiny bugs. It is imperative to find new, efficient and ecological control methods.
"In fact, the method has never been far away from us," lu Jiale, deputy director of the Natural Enemy Center, casually opened the leaves in the courtyard of the plant protection center, looked at it carefully, pointed to a small white dot running quickly between the red dots, and said, "There is a predator mite here, and it is here to eat these leaf mites." ”
As the saying goes, "where the poison is, there is a nemesis within ten steps", although it is not accurate, it does depict a certain characteristic of the ecological chain, "a place where a creature survives, usually attracts its natural enemies to prey, and the method of natural enemy control is to find and screen those most suitable natural enemies, to suppress the number of pest populations, and even to achieve the purpose of completely controlling pest harm," said Xu Xuenong, executive deputy director of the Center for Natural Enemies and director of the Biological Control Center of the Institute of Plant Protection of the Chinese Academy of Agricultural Sciences.
Move the food chain into the lab
The scene behind the leaves happens every moment in nature. In the laboratory of the Center for Natural Enemies, the same story is happening.
The predatory mite research group led by Xu Xuenong has some special laboratories and insect breeding, which form a complete chain to help researchers conduct experiments.
This is the Predator Mite Research Group. Beijing News reporter Wang Ying photographed
Xu Xuenong, director of the Biological Control Center of the Institute of Plant Protection of the Chinese Academy of Agricultural Sciences and executive deputy director of the "National Natural Enemies and Other Insect Resources Data Center", introduced the various mites cultivated in the incubator to reporters. Beijing News reporter Wang Ying photographed
In a laboratory, there are many legumes, tobacco, etc., which are very "clean", no diseases, no pests, and the leaves are emerald green and thriving.
In the adjacent second laboratory, the same plant had a large number of white spots on its leaves, some of which had dried up, the plant was withered, the branches were covered with leaf mites, and some of the stem tips, the leaf mites would converge into clumps, as large as a matchstick, which was a precursor to their spread. This laboratory is mainly used to raise leaf mites, which reproduce freely on the stems and leaves of plants and feed freely, without any human or biological harm to them.
In the third laboratory, there are both leaf mites and predatory mites on the plants, which is where predator mites are raised, and leaf mites are their food.
Xu Xuenong introduced various mites cultivated with plants. Beijing News reporter Wang Ying photographed
Every time you enter three laboratories, you can only go from the first to the third, and the order cannot be reversed, "They are too small, and it is easy for people to take them out and take them to the next environment." Xu Xuenong said.
In another, more spacious laboratory, seven or eight students and researchers are conducting experiments. In a round plastic box, there are a few less stretched blades, and under the microscope, dense leaf mites can be seen crawling, and in some places even overlapping several layers.
Microscopic prey on mites hunt harmful mites . Beijing News reporter Wang Ying photographed
A red insect suddenly rampaged in, this is a Small Chilean Plant Mite, a kind of predatory mite, it quickly found the target, inserted the mouthpart into the body of a leaf mite, and then, in the transparent body of the Chilean Small Plant Mite, you can see the liquid constantly inhaled from the mouthparts and flowed to the abdomen. The leaf mite kept struggling, but to no avail, and in a few minutes, the leaf mite was only a transparent skin.
An adult Chilean small plant mite, can eat more than a dozen or even dozens of leaf mites every day, they breed quickly, and are very dedicated to their prey, is an excellent predatory creature, Xu Xuenong told reporters, after more than ten years of predatory mite research and development, from basic research to large-scale breeding, and then to application, have made great progress. In the prevention and control of leaf mites, "the effect is very good".
Microscopic prey on mites eating eggs of harmful mites. Beijing News reporter Wang Ying photographed
The history and today of natural enemy prevention
In the fight between humans and crop pests and diseases, the participants are never only involved in these two parties, at least the crops themselves, as well as the natural enemies of pests and germs.
Crops evolve over a long period of time to develop the ability to resist pests and diseases, which is used by breeders to breed highly resistant crop varieties. Predators, on the other hand, play a role in controlling the pest population. Of course, natural enemies themselves have their own natural enemies, and they are also food for other creatures.
In traditional agriculture, natural enemies have always existed, but people use scientific methods to analyze, screen, actively cultivate and release natural enemies on a large scale. Xu Xuenong told reporters that the earliest commercial products appeared in the late 1960s and have only been more than half a century today. However, in the past one or two decades, the natural enemy industry has advanced by leaps and bounds, and natural enemy production enterprises have sprung up, and the types and numbers of natural enemies have been greatly enriched and soared.
The red-eyed bee is a typical predator insect and one of the first commoditized predator insects. Unlike predatory mites, the red-eyed wasp is a parasitic natural enemy insect, the adult red-eyed wasp is less than 1 mm long and has a needle-shaped egg-laying apparatus that can lay its own eggs into the eggs of pests. After the eggs hatch, the larvae feed on the host's eggs and grow up, and only when they are feathered, do they bite through the parasitic egg shell and fly freely. The recipes, or hosts, of the red-eyed bee are more extensive. For example, there are dozens of hosts of the rice borer red-eyed bee, the main hosts are rice longitudinal leaf borer and dimorph borer, both of which are the most important pests in southern rice, so the rice borer red-eyed wasp has a huge advantage in protecting southern rice. Corn borer red-eyed bee, there are more than ten kinds of hosts, mainly parasitic in the eggs of corn borer, and corn borer is also a major pest that harms corn.
Battle a predator in no-man's corner
Scientists have found many more natural enemies, such as grasshoppers, people may not know its name, but must have seen it, its body length of about 2 centimeters, green throughout, with long, tulle-like wings, delicate, beautiful, like the elves in the grass, whether in the city or the countryside can be seen.
Many people do not know the meaning of its existence, it neither bites people, nor eats leaves and leaves, how does it survive? In fact, this beautiful and fragile little flying insect is a "powerful character" in nature, it eats meat, and it is an excellent predator.
The larvae of grasshoppers are not beautiful, have no transparent wings, a pointed belly, and a pair of machete-like jaws, which are natural enemies of pests such as aphids. The larval stage of grasshoppers is only about 8-15 days, and verifiable records show that each grasshopper larvae can eat hundreds of aphids in an average day, known as "aphid lions". Therefore, today, grasshoppers have been widely used in the control of agricultural pests.
Xu Xuenong told reporters that scientists have found and screened out many excellent natural enemy insects for the control of pests in different regions and different species, "such as many types of parasitic bees, predatory mites, ladybirds, predatory bugs, parasitic flies, etc." ”
Mites cultured on plants. Beijing News reporter Wang Ying photographed
Researchers who study natural enemy insects are often struck by the complex and subtle art of struggle of insects, And Lu Jiale told reporters a story about the red-ringed ladybird. Similar to the Seven-Star Ladybird, the Red Ring Ladybird is also a common predator ladybird, mainly feeding on grasshoppers, but also can also feed on a variety of other insect shells. Grasshoppers are important pests of apples, peaches, pears and other fruit trees, and are often found on urban sidewalk trees, usually occurring in the spring and causing great harm. Red-ringed ladybirds have an excellent control effect on insect-shell insect pests, and sometimes rely on natural occurrence to eliminate most grasshoppers. This is due to its unique ability to mimic, when the red ring ladybird lays eggs, it will mix its eggs into the middle of the insect shell eggs, and the hatched larvae are very similar to the grasshopper larvae, which makes it easier to feed the grasshopper larvae until it grows into an adult, and will become a ladybird. "Unfortunately, because the larvae of the red ring ladybird are very similar to the grasshopper larvae, farmers often mistakenly think that it is a pest, and when they find it, they take medicine and beat it to death." Therefore, it is still necessary to strengthen the popularization of science, develop better natural enemy products, and avoid such a situation as much as possible in the future. She said.
The study of natural enemies begins with the establishment of a "germplasm bank"
The mainland's research on natural enemies of insects started late, and the development of industrialization was relatively slow. In 2017, the "National Natural Enemies and Other Insect Resources Data Center", that is, the Natural Enemies Center, was established on the basis of the Institute of Plant Protection of the Chinese Academy of Agricultural Sciences, which is committed to the monitoring and excavation of natural enemy resources and helps the industrialization of natural enemy prevention and control.
Xu Xuenong told reporters that the work of the Natural Enemy Center began with the long-term monitoring and investigation of the background, distribution and dynamics of resources, and in the past 5 years, a large number of natural enemy resources and information have been collected.
"Nature has a rich breed of predators for us, and the list of natural enemies tells us when and where we can collect them." Xu Xuenong said.
In addition, there is a special germplasm bank in the Predator Center, which preserves natural enemy resources from all over the country. They are stored in anhydrous alcohol and stored in cold storage from zero to minus four degrees Celsius, a method that allows predatory insects to be preserved for decades and still be able to extract DNA for molecular biology research.
Lu Jiale is in a cryogenic storage room, where insect samples from all over the country are stored. Beijing News reporter Wang Ying photographed
"This is a century-old project," Xu Xuenong said, "and the study of natural enemies is a basic and long-term work." At the beginning of the center, a lot of work was focused on collection and monitoring. If we do not know the background of natural enemy insect resources, we do not know which insects can help us control diseases and insect pests, and natural enemy control cannot be discussed. In the early countries where the research on natural enemy insects in the world started, it was only after years of basic work that a large number of excellent results and products began to appear. ”
Collecting and monitoring insects is a long and complicated thing, and Sun Xingxing, a researcher at the observation and test site in Yancheng, Jiangsu Province, has to sample and monitor in the test base, farmland and protected area almost every day. He told reporters that there are many ways to sample insects, and the normal collection method includes the use of Malay net collection, sweeping net collection, trap collection, lamp seduction, sexual seduction and other methods, Malay net is one of the most commonly used methods, which is similar to a small tent-like net, the top is slope-like, narrower and narrower, there is an opening at the top, the opening hangs an alcohol bottle, because insects often only climb upwards, so they will climb all the way to the top, fall into the bottle, and periodically retract it.
Sun Xingxing (first from the left), a researcher at the observation and test site in Yancheng, Jiangsu Province, and his colleagues sample and monitor in the test base, farmland and protected area almost every day. Courtesy of respondents
In addition to routine collection, there are also targeted collections, such as for a pest or a natural enemy. Some predators are difficult to collect and are very small in their own right, while others are parasitic and lay eggs into the body of pests, making them more difficult to spot.
Compared with collection, monitoring is more difficult, insect population occurrence is dynamic, even in a specific area, it is always changing, "in a certain area, which natural enemies last year more, this year less, the reason is what?" Starting from the time dimension, it is necessary to find the reason for the change of natural enemies, if it is an abnormal change, or even a certain natural enemy is on the verge of extinction, it is necessary to intervene in time and put forward a plan. Xu Xuenong said.
During the years of monitoring, have any insects gone extinct? At least not yet, it is impossible to judge, "So far, the background investigation has not been completed, and we have not even fully figured out which species there are, so it is impossible to know whether there is extinction." ”
However, in the course of several years of monitoring and collection, a large number of samples have been preliminarily analyzed and sorted out, and some new natural enemies have been discovered, such as three new ladybirds in Yunnan, and new spider species have also been found in Jiangsu. "These new discoveries have increased the resources available to us." Xu Xuenong said.
In complex ecological chains, it is not easy to study natural enemies
Richer and more comprehensive insect resources provide a foundation for the analysis, research and product development of natural enemy insects. Xu Xuenong told reporters that in the predatory mite research group, several predatory mite products have been developed.
The Predator Center preserves some of the commercialized products, the appearance of the products is basically a straight barrel plastic bottle, which contains predator mites and the substrate that carries it, each bottle can contain thousands of predatory mites, these products have been used in agricultural production in many parts of the country, "the effect is very good, especially in the relatively closed facilities of agriculture and fruit tree production environment, can play an effective role in controlling pests", Xu Xuenong told reporters, in Beijing, there have been many greenhouses for planting strawberries, began to use predatory mite products.
Predatory mite products. Beijing News reporter Wang Ying photographed
The reason why the effect is better in facility agriculture is because the production environment of facility agriculture is simpler and more stable, Xu Xuenong told reporters that the selection, research and development, and release of natural enemy insects are not simply considering the relationship between predation and predation, "We define pests and beneficial insects, just from the perspective of human interests to determine, but in fact, they are in the food chain, far more than predators and predators. Nature is incomparably complex, and every input in nature can trigger countless direct and indirect chain reactions. Predators themselves are predators, pests we define, simply because they harm crops and compete with us for food, but in the ecological chain they are likely to have other roles. ”
Lu Jiale described another phenomenon, natural enemies will also fight and fight, she said, "such as dragonflies, everyone knows that it is beneficial insects, so if we put more dragonflies in an environment, will we make the pests disappear faster and more thoroughly?" In fact, not necessarily, after artificially releasing dragonflies, the new dragonflies may fight with the original dragonflies first, determine their respective positions in the food chain, the winner is the king, the loser dies, and the number of dragonflies is likely not to increase, and the types are more likely to decrease. There are many similar phenomena, many natural enemies can effectively control pests, but when there is less food, they will kill each other. ”
The essence of natural enemy prevention and control is to "treat insects with insects", learn from nature, and obtain resources to protect crops in nature, but it is also necessary to pay attention to the fact that farmland is not nature, learning from nature does not mean that farmland becomes a natural environment, Xu Xuenong said, "This is also one of the problems in the study of natural enemies, in nature, or in forest areas, the environment is relatively stable, the ecological chain is relatively stable, pests eat plants, natural enemies eat pests, maintain a relative balance." First of all, the farmland crop is single, lacking the basis for the survival of a variety of insects, such as some parasitic bees, need to eat nectar to supplement nutrition, which requires planting flowering plants around the farmland. Secondly, after many crops in the farmland are mature and harvested, the field becomes bare, the environment immediately changes greatly, and the ecological chain naturally changes with it, the pests may disappear, and the natural enemies will not survive. Third, people's requirements for farmland benefits are different, and the natural world is not the same, there are some pests in nature, it does not matter, but it may help the ecological balance, but the farmland pursues higher yields and pursues the absence of pests, so we must also consider this factor when we use the method of natural enemy control. ”
To prevent and control invasive alien organisms, native predators are also feasible
"Through biological prevention and control, natural enemy prevention and control, our agricultural production will be more green and healthy, this is beyond doubt, so the future of natural enemy prevention and control is infinitely broad, especially at present, consumers have higher and higher requirements for agricultural product safety, the demand for green and organic agricultural products is getting bigger and bigger, and the application prospects of natural enemy prevention and control will be better and better." Xu Xuenong said.
The prevention and control of natural enemies is of great significance in ecological development and food safety. In addition, it is also of great significance in ensuring food security, such as the prevention and control of invasive alien species.
Alien species, especially exotic agricultural pests, can cause huge losses once they invade, such as the invasion of the mainland in 2019. The invasive grassland moth has been found to harm a variety of crops and weeds such as corn, sorghum, sugar cane, millet, wheat and so on.
Prior to this, mainland scientists and plant protection systems have been tracking and monitoring for a long time, responding quickly after invasion, formulating and promoting prevention and control methods, and issuing prevention and control manuals in a very short period of time, including a variety of prevention and control methods, including the prevention and control of natural enemies. At present, several species of native predator insects of the grassland night moth have been found in Yunnan, Guangxi and other places.
Related Reading——
There are super pests, will there be super predators in the future?
Decades of research and application of natural enemy prevention and control, there are natural enemy products that can be promoted, does not mean that the research of natural enemy insects is mature enough, "our natural enemy research, many aspects are still in the initial and just beginning of development stage." Xu Xuenong said.
Predators all have their own specific recipes, some narrow and some wider. However, some agricultural pests and edible crops are diverse, and some even hundreds of species. For example, the cotton bollworm, although it looks like a pest in cotton, can actually harm more than 200 species of plants in more than 30 families. Another example is the whitefly, which can harm more than 600 plants, and these recipes are extremely widespread pests, also often referred to as "big pests" or "super pests", which are the main enemies in agricultural production, and a little carelessness may cause serious losses.
There are super pests, are there any "super predators"?
With the development of molecular biology, the whole genome sequencing of many insects has been completed, is it possible to control more pests in the future by artificially breeding a more natural enemy insect with a wider diet?
"There is such a possibility, but from the current point of view, it may not be a good choice." Xu Xuenong said, "We still know too little about insects, we don't know how many species of insects there are in the natural environment, and we don't know what roles and functions they each assume." If we breed a super predator, it may destroy more kinds of pests, but it will inevitably trigger a series of chain reactions, what kind of reaction is this, can we figure it out before using it? Maybe yes, maybe not, probably not. It's like making a super poison, we want to use it, if we have an antidote, of course, very good, but most likely there is no antidote, then dare to use it? Moreover, from the perspective of biodiversity, cultivating such natural enemies is not a good choice."
The prevention and control of natural enemies learning from nature is undoubtedly one of the main directions of biological prevention and control and green prevention and control, and it is of great significance in the future of ecological development. But it will be a long process, and it will be a process that must be cautious and have a sense of awe. Of course, in the initial stages of natural enemy research, such a choice may still be far away.
Beijing News reporter Zhou Huaizong
Edited by Tang Zheng Proofreader Yang Xuli