When American ‘troublemakers’ fly into Chinese maize fields
I knew he didn’t mean to be offensive, nor was he the type to gloat; there was more of a mocking tone towards the reality he had witnessed in his joke.
A few years ago, while managing a farm in Heyuan, Guangdong, he heard from the “workers” operating the crop-spraying drones that a formidable pest had appeared in the maize fields. It required a massive dose of chemicals to kill, and a portion of that field was growing fresh maize for human consumption.
From then on, Old Lei remembered not to buy maize from outside, but he didn’t give the insect much thought—he didn’t even remember its name. It wasn’t until two years later, after returning to his hometown in Liuzhou, Guangxi, that he encountered the pest again in his own maize fields. Local villagers told him that in the two years he had been away, this insect, known as the Fall Armyworm, had run rampant through their village.
“In my memory, maize didn’t need much spraying in the past. Now that this bug is here, you definitely have to spray more. One crop of maize needs at least six treatments; for one mu of land, you use roughly a whole jug of solution.” This direct confrontation gave him a true sense of the Fall Armyworm’s power. “The most hateful thing about this pest is that it eats the heart leaf of the maize, so you have to spray at intervals starting from the seedling stage; otherwise, the maize is eaten away just a week after sprouting. Not spraying basically means a total crop failure.”
II. Climate Change: Accelerating the ‘Pesticide Treadmill’
The Fall Armyworms that invaded China primarily target maize. Last September, while conducting household surveys in Yanta Village, Kunming, Yunnan, the villagers’ brows furrowed and their gazes sharpened the moment the Fall Armyworm was mentioned.
According to the aunties and uncles of Yanta Village, the Fall Armyworm can cause maize yields to drop by 10% to 15%, and in severe cases, lead to total crop failure—a situation very similar to what Old Lei described. One auntie said: “In earlier years, we had pests like aphids and leafhoppers, but one round of pesticide was enough. But when the Fall Armyworm first appeared, ordinary pesticides didn’t work, and we had no way to deal with it.”
This is where the trouble lies. The intensive agriculture of the Americas, with its massive use of insecticides, acted as a breeding ground that gifted the Fall Armyworm with powerful drug-resistant capabilities. This is one reason why they were able to sweep across several continents in just a few years. People use the term “treadmill” to describe the vicious cycle of over-reliance on pesticides: as insects develop resistance, people spray more pesticides until the insects become immune to everything, prompting the development of new chemical agents. The Fall Armyworm is a prime example. Because it has severely threatened global food production, the Food and Agriculture Organization of the United Nations launched a global joint action against the pest, yet it still cannot halt the insects’ advance.
And just as humans find themselves at their wits’ end facing the Fall Armyworm, climate change is accelerating the “pesticide treadmill”.
Generally, rising temperatures facilitate the migration of pests to higher latitudes and altitudes. For every 1°C increase in temperature, losses in wheat, rice, and maize caused by pests increase by 10% to 25%. The Fall Armyworm is no exception; they prefer warm environments, and their development speed accelerates significantly as temperatures rise. Research predicts that under the trend of global warming, the suitable habitat for the Fall Armyworm in China will expand further. The high temperatures and low rainfall in Yunnan in 2019 were likely key reasons why the Fall Armyworm’s growth and development accelerated, its fertility increased, and its population surged in a short period.
3. “Without chemicals, you’ll lose everything down to your underwear”
Like most farmers, Old Lei did exactly that. Despite his extensive experience in ecological farming and his knowledge of using pest-repellent enzymes to control infestations, he found he had no choice but to compromise.
“If pesticides can’t handle those bugs, pest-repellent enzymes certainly won’t,” he explained. In his own vegetable garden, Old Lei insists on going pesticide-free, but the result is that the Fall Armyworms burrow into his chillies and devour them; within a couple of days, the chillies rot and drop to the ground.
Consequently, while Old Lei doesn’t buy fresh maize from the market, he understands the position of that large-scale grower in Guangdong: “Unless you’re just doing it for fun, when you’re farming on a large scale—over 100 mu—with that much investment, who would dare not use pesticides?”
Because the overuse of pesticides over the past few decades has had severe environmental and health impacts, China began implementing a pesticide reduction plan in 2015. The challenge in combating the Fall Armyworm, therefore, lies in controlling the pest population and safeguarding food production without increasing the amount of pesticide used.
Since the Fall Armyworm invaded China, the government has invested huge sums of special funding and mobilised agricultural researchers nationwide, incorporating the pest into a monitoring and early warning network spanning more than 3,000 agricultural counties in an effort to halt its northward advance. The Ministry of Agriculture and Rural Affairs publishes annual technical schemes for the prevention and control of the Fall Armyworm. Core measures include ecological control (leveraging farmland biodiversity, such as pest-resistant varieties, intercropping, and trap crops on field margins), seed treatment, physical and chemical trapping, biological control, and the scientific application of pesticides. Some experts suggest prioritising physical and biological controls, resorting to pesticides only as a last resort.
In regions such as Guangxi, Yunnan, and Henan, biological control methods are being developed and promoted to address the increasing resistance of the Fall Armyworm to chemical pesticides. These include the introduction of natural enemies—such as parasitoid wasps, predatory bugs, and parasitoid flies—as well as the development and demonstration of biopesticides, including formulations based on *Metarhizium anisopliae*, *Beauveria bassiana*, and nucleopolyhedrovirus (NPV).
The fall armyworm creates a genuine sense of urgency for farmers, stemming not only from its pesticide resistance but also its extraordinary ability to breed and spread. Its biological characteristics are summarised as being “exceptionally mobile, voracious, and prolific”. In Lao Lei’s words: “If you spot a fall armyworm on one maize plant today and ignore it, in two days, all the surrounding maize will be infested; a few days after that, the whole field will be beyond saving. You have to spray the moment you see them.”
Farmers in Yunnan have also suffered under this plague. When the fall armyworm first arrived in Yunnan, they found that even if they killed the pests today, more would fly in from nearby tomorrow. It was only after the government hired professionals to carry out uniform spraying across the entire infested region that the situation improved. This is known as “Unified Prevention and Control”—professional, coordinated spraying designed to tackle explosive pest outbreaks. Otherwise, if smallholders only “sweep the snow from their own doorstep”, they are forced to spray more frequently, which only accelerates the development of pesticide resistance.
However, Unified Prevention and Control is best suited for large-scale monoculture regions; smallholders may not always benefit from this “perk”. For instance, in Yunnan Province, agricultural expert Li Chunliang believes that such coordinated control is difficult to implement. Where fodder maize is grown, smallholders’ plots are typically scattered, making uniform spraying impractical. For fresh maize grown for human consumption, the dose of pesticide required varies according to the growth cycle, making farmers even more hesitant to spray blindly.
In such cases, Li Chunliang argues that the only solution is to teach smallholders scientific application techniques, such as selecting the correct pesticides and rotating them, to control pests without relying on excessive chemicals.
And in truth, farmers do not want to use so many pesticides. According to Lao Lei’s calculations, the cost of pesticides per mu has risen to around 200 yuan, and in many cases, growing maize has become a loss-making venture for smallholders.
IV. More Than Just Insects Spreading
At the end of 2023, the Ministry of Agriculture and Rural Affairs approved business licences for genetically modified maize and soya for 26 companies. In 2024, another batch of biosafety certificates for GMOs was issued, signalling the full-scale promotion of GMO seeds in China. Consequently, last year has been dubbed the “first year of GMO commercialisation” in China. Accordingly, the 2024 technical plan for fall armyworm control has been updated to include a new priority: “preferentially use pest-resistant GM maize”.
However, a control guide published by the Food and Agriculture Organization of the United Nations suggests that it is too early to conclude whether GM maize can effectively control the fall armyworm: “Bt maize has been shown to reduce damage from fall armyworms, but the African fall armyworm has developed resistance to some Bt maize varieties.” (Note: Bt refers to *Bacillus thuringiensis*, a beneficial insecticidal microbe widely present in soil. Scientists transfer the insecticidal protein gene from Bt into maize, enabling the plant to produce this protein. Since its commercial approval in the US in 1996, Bt maize has been widely planted in many countries.)
But for Lao Lei, the frequency of spraying per maize crop has increased from once to six times; scientists are racing to develop new pesticides to keep up with the insects; and finally, we resort to altering the genetics of the seeds. Is this the kind of adaptation we hoped for?
This is precisely what is worrying: not every effort to use technology to solve a crisis leads to a positive outcome. Reflecting on the history of the fall armyworm’s increasing resistance over the past few decades seems to confirm one fact: humanity’s attempt to seek production certainty by controlling nature has ultimately led to an ecological crisis that leaves us living in an increasingly uncertain world. We must ask: will the “pesticide treadmill” run forever? And if it does stop, in what way will it be?
References
https://d.wanfangdata.com.cn/periodical/rdzwxb201906028
http://www.ere.ac.cn/cn/article/pdf/preview/10.19741/j.issn.1673-4831.2019.0487.pdf
https://www.fao.org/fall-armyworm/monitoring-tools/faw-map/en/
http://journals.caass.org.cn/zgnxtb/CN/10.11924/j.issn.1000-6850.casb20191100857
http://www.moa.gov.cn/nybgb/2022/202212/202301/t20230104_6418252.htm
https://www.sciencedirect.com/science/article/pii/S2351989421005448
Editor: Ling Yu