Lei Haoran, reporter of China Youth Daily and China Youth Network, Li Runwen
"We are not afraid of the enemy's teeth and claws, but we are afraid that the enemy is everywhere." This is what Professor Hu Gao of the College of Plant Protection of Nanjing Agricultural University said when he talked about pest control.
In the past two years, what has most affected Professor Hu Gao's nerves is the major migratory agricultural pest grassland night moth that the United Nations Food and Agriculture Organization has warned of globally. This is a sudden invasion of biological species. The grassland nocturnal moth, a harmful insect that originated in the tropical and subtropical atmosphere of the Americas, has swept through Africa, Europe, over India, and even reached the arid and cold regions of northern China such as Shanxi and Gansu.
This summer, Professor Hu Gao's itinerary was full, and he went to Yunnan, Henan and other places to investigate the occurrence of crop damage and insect pests.
This year's climate is particularly unusual compared to previous years. Winter and spring temperature is abnormally high, the amount of overwintering insects is large, migratory pests fly by the wind, stopped in the rain, the ultra-long rainy season disrupted the original migration route and occurrence law, many places appeared migratory flying pests in a large area of pest phenomenon.
In the past, in the face of this situation, people often had to run after pests and chase after their butts.
Now, using big data capture and prediction, Professor Hu Gao and his team want to turn passive pursuit into active squatting, passive warfare into active warfare, and comprehensively block species invasion.
Track the meadow moth
At the beginning of 2019, the grassland night moth was found in Yunnan, China. Professor Hu Gao, who studies pest control, learned of this news, and his nerves tensed. Previously, he had been following the latest movements of the grass moth.
The larvae of the grassland moth are grey-green , with inverted " Y" spots on the head and four black spots on the cephalic segments of the abdomen, arranged in a square pattern. This is a very edible pest, the larva parasitizes on crop plants, feeds on the leaves and stems of crops, and is very harmful to more than a dozen crops such as corn, rice, sorghum, sugarcane and so on. They lay their eggs directly on the leaves. The larvae cut off the stems of seedlings and young plants, biting off the plant's growth points, causing plant death. A small grass moth larvae can destroy an entire corn seedling. Crops that are exposed to insect infestations can reduce yields by up to 20 per cent, which can seriously lead to no harvest of pellets.
The meadow moth originated in the tropical and subtropical regions of the Americas and was only active in the Western Hemisphere until 2016. The discovery of the grassland moth in Africa in 2016 proves that it has produced transcontinental transmission. Professor Hu Gao began to follow up the study, and he proposed to prepare for the invasion of Asia and even China by the grassland moth.
His fears were confirmed. In May 2018, the grassland nightcrawler invaded India and appeared in Yunnan, China last January.
As a typical migratory insect, the adult of the grassland nightcrawler can fly 100 km (flies only 15 km) overnight with the help of wind, a speed unprecedented in the entire pest world. In addition, the reproductive ability of the grassland nightcrawler is also quite amazing. Under the condition of about 25 °C, the grassland moth can breed a generation in about 30 days. Each egg can be laid 100 to 200 eggs, 900 to 1000 eggs can be laid in a lifetime, and can reproduce several generations a year.
When the migration path is not yet clear, it is extremely difficult to predict in time. Even if the country adopts the posture of "strict prevention and death", in 2019, the grassland night moth still affected nearly 1,500 counties and cities in 26 provinces across the country. In January 2019, the grassland night moth was found in Yunnan, migrated to Hubei in May, and in July, the larvae of the grassland night moth also appeared in Shanxi and Gansu.
"Once the grassland night moth forms a settlement in our country, the loss is immeasurable." Professor Hu Gao believes that at this stage, it is the top priority to grasp the migration path of the grassland night moth and predict it in time.
Establish monitoring outlets for close tracking
Time is tight, the task is heavy, and most importantly, the property damage of farmers is difficult to measure and predict. Professor Hu Gao said that in the past two years, the grassland moth has not yet formed a settlement in China, on the one hand, due to the strict prevention and control of the whole country, on the other hand, it is also due to the abnormal weather this year, which will "contain" a large number of grassland moths in Yunnan and Guizhou.
This year is the second year that the grassland moth has invaded our country, and there is still a wide range of risks in the future. Professor Hu Gao and his team grasped monitoring with one hand and modeling with the other.
With the help of a large number of first-hand data, and according to the existing migration data of grass moths similar to insects, Professor Hu Gao established a data model in a short period of time and initially established the migration route of grassland moths.
Unlike Professor Hu Gao's many-site investigations and investigations, several of his graduate students have been stationed in pest occurrence sites for a long time to study and monitor, and strive to collect first-hand information. In the countryside of Yunnan, these young people have been stationed for more than 5 months.
Chen Hui, a doctoral student at Nanjing Agricultural University, is one of them. Since March, Chen Hui has been monitoring and researching in Yuanjiang County, Yunnan Province.
He often got up at 6 a.m., experimented in the fields, went to the countryside to publicize, and went to the ground to catch insects. It was hot, but they were unambiguous about their work. At night, it is the activity time of the grassland moth, and they often rush to test the data and complete the relevant topics during this time period.
Yuanjiang County, Yunnan Province, is located in a low-heat river valley area, and it often does not rain for more than 40 consecutive days in the middle of summer, and the average temperature in summer is as high as 37 °C. "At first we worked wearing long sleeves, long pants, and hats, but then we gave up when we thought it was too hot." Until now, Chen Hui's arm still had spots from the scorching heat.
However, the lack of tools to build monitoring points in the field allowed the Doctoral Student to experience the embarrassment of a "barefoot doctor".
This feeling is especially strong when recording the route of migrating insects.
Recording insect migration routes requires a professional flight simulator. Chen Hui's laboratory has imported flight simulators, but he can't bring them to the fields, so he can only make flight simulators by hand.
The most difficult part of the development of flight simulators was to solve the problem of how to use microcontrollers. That is, how the microcontroller and the encoder in the flight simulator are connected, and how to transmit data with the computer. "The data is collected, and if you can't visualize the upload, you will lose your previous efforts."
Chen Hui specially bought online courses, and bought a 51 microcontroller learning machine, but there are many key problems that rely on self-study, online courses lack feedback, and there is no place to ask when encountering difficulties. None of the lab members, including Professor Hu, had relevant experience. By chance, one day Chen Hui saw a friend forwarding relevant knowledge when brushing the circle of friends, and he hurried to contact this friend.
Finally, Chen Hui took down the microcontroller part of the flight simulator device, which made all the data he collected finally transformed into a chart that could be studied and a migration path map.
Throughout the process, Chen Hui received a lot of help from Professor Hu Gao: "He was very supportive of the students' ideas, and when I was doing flight simulators, he asked me to boldly let go of my hand and do it." ”
It is the "monitoring network" built by Professor Hu Gao and his team in various places that makes data prediction possible.
Turn passive pest control into active field defense
At present, Professor Hu Gao and his team have set up more than a dozen experimental communities in the experimental area of Yunnan, using insect traps, high-gloss lamps, sex attractants and other methods to capture the grassland night moth, and then count the number. The monitoring point has been built to integrate the paths of countless grassland moth migrations, which is the flight migration roadmap.
It's a long and tedious process. Professor Hu Gao introduced: "The amount of data is very large, the number of inputs is frequent and the data structure is complicated, and the data entered by a graduate student in one night is modified 9 times. ”
According to the predicted model, in southern China, including Guangdong, Guangxi, Yunnan, Fujian, Taiwan and other provinces and Hainan Island, in addition to the local overwintering population of grassland night moth, in March and April, there will be a continuous migration of insect sources from overseas grassland night moths into China. In most areas south of the Yangtze River, adult insects can move in in March, and the main migration period is April and May. From April and May, jianghuai, huanghuai region, north China plain, Sichuan basin and most areas of Guizhou province, there have been sporadic migration of insect sources in the area south of the Yangtze River, and the main migration period is May and June. The main migration period for the areas north of the Yellow River is July, while adults may not move in until July in the northern parts of eastern Gansu Province, Ningxia Hui Autonomous Region, Shaanxi, Shanxi and Hebei provinces, southern Inner Mongolia Autonomous Region and northeast China. Their predictions are also basically consistent with the trend of the outbreak of grassland moths in the past two years, which provides strong theoretical support for the formulation of the three-zone and three-belt deployment plan for grassland moths in China.
Professor Hu Gao believes that the wintering area in South China, the Huang-Huai-Hai region and the southwest and northwest corn areas are the focus of the control of grassland night moth. At present, under the circumstance that the grassland moth has not yet formed a settlement in China, a comprehensive control technology system of chemical control, physical control, biological control and agricultural control should be established within one or two years. The basic idea of prevention and control is to implement zoning management according to local conditions, monitor and trap adult insects early, prevent the large-scale migration of grassland moths, focus on the prevention and control of larvae, and avoid outbreaks.
While understanding the dynamics and flight behavior of pests, Professor Hu Gao based on the meteorological data provided by the US NOAA database in the past 5 years, through the insect migration trajectory algorithm, the insect's own flight ability as a parameter for data calculation and analysis, to make accurate predictions.
Professor Hu Gao hopes that in the future, through the prediction of big data, we can prepare for the arrival of pests before they arrive, and turn passive pest control into active field defense. "Now, we can at least say that the timing and location of the grass moth next year are predictable." Professor Hu Gao said.
The desperate struggle between the migratory pests and the farmland guards is still surging in the quiet field.
Source: China Youth Daily client