Recently, the Proceedings of the National Academy of Sciences (PNAS) published online a collaborative research result by Professor Hu Gao's team from Nanjing Agricultural University and Researcher Feng Hongqiang's team from Henan Academy of Agricultural Sciences. The research reveals the scale and migration behavior patterns of nocturnal flying insects in the eastern region of China.
Every year, billions of insects fly across the sky, seeking breeding grounds hundreds of miles away. The massive migration of insects can lead to explosive agricultural pests, causing devastating losses; serve as vectors for diseases affecting humans, livestock, and plants; or provide specific ecological services as pollinators or natural enemies of pests.
Due to the unique atmospheric and geographical conditions in East Asia (East Asian monsoon climate and relatively flat terrain), most major outbreak pests in China exhibit migratory behavior, posing a serious threat to China's food security. However, due to the small size of individual insects and their migration at high altitudes spanning hundreds to thousands of kilometers, monitoring their long-distance aerial migration process directly is challenging, and the scale and behavior of airborne insect populations remain understudied.
Insect radar is a powerful tool for monitoring insect aerial migration, capable of monitoring insect flights around the clock. Based on insect vertical radar monitoring data from the Plant Protection Institute of Henan Academy of Agricultural Sciences in Xinxiang from 2015 to 2017, the study successfully estimated the number and biomass of airborne migrating insects in the eastern region of China: approximately 9.3 trillion insects engage in long-distance aerial migration over eastern China each night, with a biomass of about 1.5 million tons.
Compared to the previously estimated migratory insect scale in southern England by the Hu Gao team, the number and biomass of nocturnal migrating insects in eastern China are 5.15 and 8.02 times that of the UK per unit area, respectively. Furthermore, the study found that the dominant insect group in China's migratory insects is Lepidoptera pests, accounting for 76.2% of the insect population. Larger insects (weighing over 10mg) exhibit seasonal directional behavior, migrating north in spring and summer and returning south in autumn, with the biomass of southward migration being only 66% of that of northward migration in spring and summer.
The Hu Gao team has long been engaged in the study of migratory insects and early warning of pest outbreaks. The team has developed high-throughput data analysis software for insect vertical radar, optimized algorithms for calculating airborne insect population and biomass, and analyzed migration behavior, achieving efficient and standardized analysis of massive radar monitoring data. This study, for the first time internationally, estimated the number and biomass of airborne insect populations, revealing the significant ecological functions of insect migration.
The research uncovers the aerial patterns and migration behavior of Chinese migratory insects, confirming the reliability and application value of Chinese insect vertical radar technology. This will further promote the construction of China's insect radar monitoring network and advance the upgrading of monitoring and early warning technologies for migratory pests in China.
Dr. Huang Jianrong from Henan Academy of Agricultural Sciences is the first author of the paper, with Feng Hongqiang, Hu Gao, and Visiting Professor Jason Chapman from Nanjing Agricultural University as corresponding authors.
Related paper information: https://doi.org/10.1073/pnas.2317646121
