Professors of Southern Agricultural University use big data to predict migrating pests and guard against species invasion
Meadow Spodoptera
"Don't be afraid of the enemy's teeth and claws, and the enemy will be pervasive." This is Professor Hu Gao from the School of Plant Protection of Nanjing Agricultural University when he talked about pest control.
In the past two years, what has touched the nerves of Professor Hu Gao most is the major migratory agricultural pest Spodoptera frugiperda in the FAO Global Warning.
This is a sudden invasion of biological species.
Spodoptera frugiperda, this harmful insect that originated in tropical and subtropical America has swept across Africa, Europe, across India, and even reached the arid and cold northern regions of my country such as Shanxi and Gansu.
This summer, Professor Hu Gao’s schedule was full. He went to Yunnan, Henan and other places to investigate the damage of crops and the regularity of pests.
Compared with previous years, the climate this year is particularly abnormal.
The temperature is abnormally high in winter and spring, and the amount of overwintering insects is too large. Migratory pests fly by wind and stop in rain. The long rainy season disrupts the original migration route and occurrence pattern, and many places have appeared. A phenomenon in which migratory pests damage a large area.
Faced with this situation in the past, people often had to run with the pests, chasing their buttocks to chase and block.
Now, using big data to capture and predict, Professor Hu Gao and his team want to turn passive pursuit into active defense, and passive warfare into active warfare, so as to fully prevent species invasion.
Tracking Spodoptera frugiperda
In early 2019, Spodoptera frugiperda was discovered in Yunnan, my country.
Professor Hu Gao, who studies pest control, got nervous when he heard the news.
Prior to this, he had been paying attention to the latest developments of Spodoptera frugiperda.
The larvae of Spodoptera frugiperda are gray-green, with inverted Y-shaped spots on the head and 4 black spots on the end of the abdomen, arranged in a square.
This is a very edible pest. The larvae are parasitic on crop plants and feed on the leaves and stems of crops. They are very harmful to more than a dozen crops such as corn, rice, sorghum and sugar cane.
They lay eggs directly on the leaves.
The larvae will cut off the stems of seedlings and young plants, bite off the growth points of the plant, and cause plant death.
A small Spodoptera frugiperda larva can destroy an entire corn seedling.
Crops that suffer from pests may reduce their yields by 20%, and in severe cases, they may lead to no harvest.
Spodoptera frugiperda was only active in the Western Hemisphere.
The discovery of Spodoptera frugiperda in Africa in 2016 proved that it has spread across continents.
Professor Hu Gao began to follow up and research, and he proposed to make preparations for the invasion of Spodoptera frugiperda in Asia and even China.
His worry was confirmed.
In May 2018, Spodoptera frugiperda invaded India and appeared in Yunnan, my country in January last year.
As a typical migratory insect, the adult of Spodoptera frugiperda can fly 100 kilometers overnight (only 15 kilometers for flies) with the help of wind. This speed is unprecedented in the entire pest world.
In addition, the reproductive ability of Spodoptera frugiperda is quite amazing.
Spodoptera frugiperda can reproduce one generation in about 30 days under the conditions of 25℃.
It can lay 100-200 eggs each time, 900-1000 eggs can be laid in a lifetime, and it can reproduce several generations a year.
When the migration path is not yet clear, it is extremely difficult to predict in time.
Even though the country has adopted a "strictly guard against death" posture, in 2019, Spodoptera frugiperda still spread to more than 1,500 counties and cities in 26 provinces (regions and cities) across the country.
In January 2019, Spodoptera frugiperda was discovered in Yunnan and migrated to Hubei in May. In July, Spodoptera frugiperda larvae also appeared in Shanxi and Gansu.
"Once the Spodoptera frugiperda settles in our country, the loss will be immeasurable." Professor Hu Gao believes that at this stage, to master the migration path of the Spodoptera frugiperda, timely prediction is the top priority.
Establish a monitoring network for close tracking
Time is tight and tasks are heavy. The most important thing is that it is difficult to measure and predict the property losses of farmers.
Professor Hu Gao said that in the past two years, Spodoptera frugiperda has not yet established a settlement in my country. On the one hand, it is due to the strict prevention and protection of the whole country, and on the other hand, because of the abnormal weather this year, a large number of Spodoptera frugiperda has been "contained" in Yunnan, China. Guizhou area.
This year is only the second year that Spodoptera frugiperda has invaded our country, and there is still a risk of widespread damage in the future.
Professor Hu Gao and his team focused on monitoring and modeling with the other.
With the help of a large amount of first-hand data, and based on the existing data on the migration of Spodoptera frugiperda, Professor Hu Gao established a data model in a short period of time, and initially established the migration route of Spodoptera frugiperda.
Different from Professor Hu Gao's investigations and surveys in many places, several of his graduate students have been stationed in pests for a long time for research and monitoring, trying to collect first-hand information.
In rural Yunnan, these young people have been stationed for more than five months.
Chen Hui, a doctoral student at Nanjing Agricultural University, is one of them.
Since March this year, Chen Hui has been monitoring and investigating in Yuanjiang Hani and Yi Autonomous County, Yunnan Province.
He often gets up at 6 o'clock in the morning to conduct field experiments, go to the countryside to publicize, and go to the ground to catch insects.
Although the weather is hot, their work is absolutely unambiguous.
Night is the active time of Spodoptera frugiperda. They often rush to check data and complete related topics during this time period.
Yuanjiang County of Yunnan Province is located in a low-heat valley area. It often does not rain for more than 40 days in midsummer, and the average temperature in summer is as high as 37°C.
"In the beginning we were still wearing long sleeves, trousers, and hats to work, but then we felt too hot and gave up." Until now, Chen Hui still has spots on his arms that were exposed in the heat.
However, in the construction of monitoring points in the field, the incomplete tools made the doctoral student experience the distress of a "barefoot doctor".
This feeling is especially strong when recording the route of migrating insects.
To record the migration route of insects, a professional flight simulator is required.
Chen Hui’s laboratory has imported flight simulators, but he can’t bring them to the field. He can only make flight simulators manually.
In the process of developing a flight simulator, the most difficult part is to solve the problem of how to use the microcontroller.
That is, how to connect the MCU and the encoder in the flight simulator, and how to transmit data to the computer.
"Data collected, cannot be uploaded visually, and all previous efforts will be lost."
Chen Hui bought an online course and bought a 51 single-chip learning machine. However, there are many key problems that can't rely on self-study. The online course lacks feedback and there is no place to ask when encountering difficulties.
None of the laboratory members, including Professor Hu, have relevant experience.
By coincidence, one day Chen Hui saw a friend repost related knowledge while browsing Moments, and he hurriedly contacted this friend.
Finally, Chen Hui took down the single-chip part of the flight simulator device.
This allows all the data he collected to be transformed into a chart and a flight path diagram that can be studied.
Throughout the process, Chen Hui received a lot of help from Professor Hu Gao: "He is very supportive of the students' ideas. When I was working on a flight simulator, he asked me to boldly let go of it."
It is the "monitoring network" built by Professor Hu Gao and his team in different places that makes data prediction possible.
Turn passive pest control into active sanitation
At present, Professor Hu Gao and his team have set up more than a dozen test plots in the experimental area of Yunnan, using methods such as insect traps, high-light lamps, and sex attractants to catch Spodoptera frugiperda, and then count the numbers.
The monitoring point has been built, integrating the countless migration paths of the grasshopper moths. This is the flight migration route map.
This is a long and tedious process.
Professor Hu Gao said: “The amount of data is large, the number of entries is frequent and the data structure is complicated. A graduate student modified the data entered 9 times in one night.”
According to the constructed prediction model, in January, in southern South China, including Guangdong, Guangxi, Yunnan, Fujian, Taiwan and other provinces, as well as Hainan Island, there were local populations of Spodoptera frugiperda who were overwintering. In March and April, there began to be overseas The insect source of Spodoptera frugiperda migrated to China.
In most areas south of the Yangtze River, adults can migrate in March, and the main migration period is April or May.
The Jianghuai, Huanghuai area, North China Plain, Sichuan Basin and most areas of Guizhou Province have sporadically migrated from the area south of the Yangtze River from April to May. The main migration period is May and June.
The main migration period for areas north of the Yellow River is July, while in eastern Gansu Province, northern Ningxia Hui Autonomous Region, Shaanxi, Shanxi and Hebei provinces, southern Inner Mongolia Autonomous Region, and northeastern regions, adults may not migrate until July.
Their prediction results are basically consistent with the trend of the outbreak of Spodoptera frugiperda in the past two years, providing strong theoretical support for the formulation of the national three-zone and three-zone defense plan for Spodoptera frugiperda.
Professor Hu Gao believes that the wintering area in South China, the Huanghuaihai area, and the southwest and northwest corn areas are the focus of the prevention and control of Spodoptera litura.
In the current situation that Spodoptera frugiperda has not yet settled in our country, a comprehensive control technology system with chemical control, physical control, biological control and agricultural control should be established within one or two years.
The basic prevention and control idea is to implement zoning management according to local conditions, early monitoring and trapping of adults, preventing the large-scale migration of Spodoptera frugiperda, focusing on the control of larvae, and avoiding explosive hazards.
While understanding pest dynamics and migratory behavior, Professor Hu Gao, based on the meteorological data provided by the US NOAA database for the past 5 years, adopted the insect migratory trajectory algorithm to calculate and analyze the insect's own flight ability as a parameter to make accurate calculations. prediction.
Professor Hu Gao hopes that in the future, through the prediction of big data, we can make preparations before the arrival of pests and turn passive pest control into active defense.
"Now, at least, we can say that the time and location of the attack of Spodoptera frugiperda next year are predictable." Professor Hu Gao said.
The fight between the migrating pests and the farmland guards is surging in the quiet field.
Lei Haoran, China Youth Daily·China Youth Daily reporter Li Runwen Source: China Youth Daily