Recently, a research team from Nanjing Agricultural University and their partners from Henan Academy of Agricultural Sciences have carried out a study. The research successfully deciphered the scale of nocturnal migrating insect populations in eastern China and their migration behavior patterns, and this landmark achievement has been published online in the Proceedings of the National Academy of Sciences of the United States of America.
The study reveals that every year, an astonishing number of insect swarms fly through the night sky seeking distant breeding grounds. These massive swarms of insects may not only become triggers for large-scale outbreaks of agricultural pests, causing substantial crop damage, but can also act as vectors spreading widespread diseases among humans, livestock, and plants. Additionally, the swarms include pollinating insects and natural pest control agents that provide ecological services.
Since most of the outbreaking pests in China are migratory, this poses a severe threat to China’s food security. However, monitoring their migration is extremely difficult because insects are tiny and can migrate at heights of several hundred or even thousands of meters, which leads to a lack of understanding of the scale of airborne insect swarms and their migratory behaviors. Insect radar, as a powerful monitoring tool, can assist in the all-day monitoring of insect migration.
Based on data from vertical insect radar from 2015 to 2017, the research team estimated the numbers and biomass of nocturnal migrating insects in eastern China. The results show that about 93 trillion insects migrate long distances through the night sky annually, with a total biomass of around 15,000 tons. Compared to related research data from the southern region of the UK, the numbers and biomass of nocturnal migrating insects in eastern China are 5.15 times and 8.02 times higher, respectively.
The study also found that the dominant groups during insect migration were pests from the Lepidoptera order, accounting for 76.2% of the total. It also indicated that larger insects exhibit clear seasonal directional migration behaviors. They tend to migrate north in spring and summer, while in autumn, they often choose to return south. However, the total biomass recorded migrating south is only 66% of the volume migrating north during spring and summer.
In summary, this study not only showcases the aerial patterns and migration behavior of migrating insects in China but also validates the application value and reliability of vertical insect radar technology in China. This will provide important support for the establishment of China’s insect radar monitoring network and promote the development of monitoring and early warning technologies for migrating pests.