13.05.2025
New research shows that large-scale climate oscillations like El Niño–Southern Oscillation (ENSO) not only cause local weather variable but also drive migratory pest outbreaks. These pests originate in Mainland Southeast Asia and ride ENSO-altered wind patterns into China, where they inflict additional rice crop losses. The study urges international cooperation to combat this twin threat to food security.
In a study just published in Nature Food, the authors reveal a previously underappreciated cause of crop failure: periodic climate oscillations which fuel insect pest invasions across national borders. It has long been known that El Niño and similar climate cycles can bring droughts or floods that damage agriculture. Now, an international research team has found that these oscillations also catalyze outbreaks of migratory pests in one region that led to devastating crop yield losses in other regions. “Our results show a kind of double trouble,” the authors report – climate events like ENSO can hit crop yields directly via weather anomalies, and indirectly by unleashing waves of pests from distant areas.
ENSO triggers pest outbreaks beyond local weather effects
The team analyzed several decades of data on Chinese rice yields, regional climate records, and pest occurrences. Focusing on the past 40 years, they identified El Niño–Southern Oscillation (ENSO) as the primary climate oscillation linked to extreme yield losses in China, particularly in the south.
Surprisingly, those ENSO-related crop failures weren’t explained sufficiently by local weather effects. In addition to droughts or heatwaves,
the researchers observed unusually high infestations of crop pests and diseases during strong ENSO years. This pointed to an indirect pathway: something about ENSO was causing pest populations to surge.
Digging deeper, they discovered that
the pest outbreaks were not only driven by local climate anomalies. Instead, the origin was traced southwards. “We found a clear link between ENSO and pest conditions in Mainland Southeast Asia,” says Dr. Chenzhi Wang, lead author from the PB3 CSA group in ZALF.
During El Niño years, climate anomalies driven by ENSO in Southeast Asia apparently create favorable breeding conditions for certain rice pests. By the following spring, the
changing position of ENSO alters atmospheric circulation – essentially changing wind patterns – which then carry swarms of insects northward into China. In other words,
major rice pests like the brown planthopper, white-backed planthopper, and rice leaf-folder, first outbreak in Mainland Southeast Asian and then migrate to Chinese rice belts due to favorable wind conditions.
Once these migratory pests invade China, they exacerbate damage to crops associated with bad weather. The study found that years with strong El Niño events often coincided with severe pest occurrence in southern China, and those years saw significantly lower rice yields. For instance, provincial records showed rice output was substantially reduced during heavy rice planthopper outbreak years compared to normal years. Detailed analysis also confirmed that the pests themselves contributed to the yield losses: even after accounting for local climate variability, rice yields dropped further when pest occurrence was high. This two-pronged impact – direct weather stress and indirect pest damage – helps explain why ENSO years are so destructive for farmers.
International collaboration needed to protect harvests
Critically, these pest invasions represent a cross-border mechanism of crop failure, originating in pest “nursery” regions such as Vietnam, Laos, Myanmar, and other parts of continental Southeast Asia. The researchers warn that as climate change potentially increases the frequency of ENSO events, the risks posed by these transboundary pests could escalate further. “Effective adaptation will require joint pest monitoring and management efforts across countries,” emphasizes by another author, Dr. Xuhui Wang, Associate Professor at Peking University. The study advocates for cross-border collaboration between the pest source countries and the affected regions, such as China, including coordinated early warning systems, shared pest outbreak data, and enhanced technical exchanges and training programs for pest management personnel.
Dr. Chenzhi Wang further notes that similar pest-driven yield losses might threaten European agriculture. Previous research has shown migratory pests from North Africa regularly cross the Mediterranean and pose threats to European crops. Additionally, the Western Mediterranean Oscillation often correlates with crop yield declines in southern European countries. "We don’t yet know if there’s a direct link between these events, but it highlights a critical research gap. Future studies in Europe should focus more closely on understanding these connections," he suggests.
The research was conducted by an international team from ZALF, Peking University, Potsdam Institute for Climate Impact Research, and other institutions in China, France and Finland. This study has received funding from the National Natural Science Foundation of China (grant nos. 42361144876 and 42171096), Horizon Europe research and innovation program under the Marie Skłodowska-Curie grant agreement no. 101154967 and the Leibniz Female Professorship Award (application no. P102/2020)
link to publication:
