- Climate change is colliding with land use practices, deforestation and biodiversity loss to drive a rapidly growing threat of crop pests.
- Future warming of 2° Celsius (3.6° Fahrenheit) above preindustrial levels (likely by the 2040s or 2050s, according to current projections) could see substantial losses of staple crop yields for wheat (an estimated 46% loss), rice (19%) and maize (31%) due to pest infestations, according to a recent paper.
- Temperate regions are likely to see the greatest increases in crop pests as warming creates conditions for migrating subtropical species to establish themselves in previously unhabitable areas.
- The authors underline the need for more pest monitoring, diversification of farmland crops and biotechnological solutions to meet this growing threat.
Climate change, land use change and biodiversity loss are combining to drive an increase in agricultural pests and expansion of their ranges with concerning implications for future global food security.
In a recent paper published in the journal Nature Reviews Earth & Environment, an international team led by researchers at China’s Hebei University assessed that 2° Celsius (3.6° Fahrenheit) warming over preindustrial levels could lead to increased pest damage and global crop yield losses of 46% for wheat, 19% for rice and 31% for maize.
The complex causes for this pest population explosion: Temperature increases are enabling crop pests to move from the subtropics into higher latitudes and to higher ground, while agricultural expansion and biodiversity loss drives down natural pest controls. International trade networks are also exacerbating the introduction of destructive invasive species, with major economic consequences, the researchers write.
“Crop pests are increasing in abundance, geographical range and reproductive capacity due to climate warming, land conversion and agricultural intensification,” Daniel Bebber, an ecology professor at the University of Exeter and a study author, told Mongabay.
It is estimated that 40% of crops may already be destroyed before harvest due to pests globally, resulting in billions of dollars in losses annually.
“Anything that’s going to increase that loss is problematic,” says Sanford Eigenbrode, distinguished professor of entomology, plant pathology and nematology at the University of Idaho, U.S., and a study author. Unpacking the implications of these projected large-scale staple crop losses on global food security and food prices is a “whole other paper,” he says.
A question of latitudes
Temperate regions are expected to be worst hit by increasing pest populations, as a global warming-wielded double-edged sword extends temperate growing seasons but also enables pest species proliferation. “Temperate regions will see both potential increases in crop yields and an increase in the pests that attack the crops,” during a longer growing season, Bebber says.
A different scenario is likely to play out across the tropics.
“Pests at mid-high latitudes [will] respond more positively to warming than those in the tropics,” says Chinnu Raju, a researcher at the Agro Climate Research Centre at Tamil Nadu Agricultural University, India. However, in tropical regions, a decrease in pest growth rate will likely occur under future warming because temperatures have “already reached the optimum level for pest development.” Combined with changing climatic patterns, including rainfall frequency and intensity, that may drive down numbers of some pests in the tropics, particularly smaller species.
Raju was not involved in the recent study but authored a 2024 paper describing climate change as an “existential” threat to tropical fruit crops. “Climate change directly affects pest reproduction, development, survival and dispersal and indirectly affects natural enemies, predators, competitors, vectors and mutualists,” he says. Consequently, it’s a threat to the existence of crops that can ultimately affect global food and nutritional security as well as farmer livelihoods.
The scientist points to the example of Pentalonia nigronervosa, an aphid responsible for transmission of banana bunchy top virus. This disease is considered one of the major threats to banana crops and can cause yield losses upward of 90%. Outbreaks in East Africa between 2005 and 2010 wiped out entire crops, sparking a food crisis.
However, the aphid transmits the virus more efficiently at temperatures between 25°C and 30°C (77°F and 86°F), he says. “Hence, the rise in temperature [due to climate change] can accelerate infestation of some pests in the tropics, but if the temperature goes beyond its maximum threshold level the reverse effect will be observed.”
Simply put, under future warming in the tropics, both crops and pests wither: “It just gets too hot for everything,” Bebber says.
In temperate regions, a lot of uncertainty remains, and generalizing the spread of pests is difficult, though it is expected climate change will increase pest range and abundance and alter pest stages of development, Eigenbrode says. Many subtropical pests migrating into temperate zones will arrive in regions at the lower end of their thermal range, so these species will have lots of capacity for population growth.
One example is the fruit fly Drosophila suzukii. Originating in Asia, this pest arrived in Europe around 2008, significantly affecting fruit yields in many countries. A paper published in 2023 indicates that warmer European winters reduce the pest’s need to become dormant, favoring its reproduction and further spread.
It’s expected that climate extremes, such as drought and heat waves, could add to a proliferation of some pest species. On the flip side, however, these extremes could also drive down pest numbers or change the prevalence of certain species in some areas.
Careless land use change and agricultural practices, such as extensive reliance on monocultures and continued conversion of forests to farmland, could also minimize the number of natural pest predators, adding to crop damage.
Tackling pests, tackling climate change
In Bebber’s view, the looming pest threat confronted at 2°C could be combated with multiple solutions focused on better landscape management techniques and biotechnology, both of which should be implemented quickly to reduce risk. This “two-pronged” approach is needed to “get us out of this dead end of oversimplified, genetically uniform production systems, which are highly vulnerable,” he says.
The recent study lays bare the need for a diversified approach that addresses both the root causes of climate change and that introduces proactive changes to agricultural practices to buffer against the pest menace.
“We need to get much better at implementing integrated pest management and biological controls,” Bebber says. “Then we need to think more deeply about the role of diversity and diversification from the genetic level all the way up to the landscape level to give us some resilience to unexpected impacts.”
The research team also called for increased pest monitoring and “climate-smart management” strategies focused on key crops such as wheat, rice, maize and soy. And, “Where climate change actually results in a mitigation of pest pressure for whatever biological reason or management reason, we should be attentive to the opportunities that presents to reduce our reliance on insecticides,” Eigenbrode adds.
Diversifying farmlands and moving away from monocultures could offer protection against pests, along with climate and economic shocks, Bebber says. While land use changes, such as deforestation and cropland expansion, can boost the proliferation of pests, crop diversification can promote natural pest control, the study notes.
Raju agrees that genetics research and changes in land management practices are key. “Breeding techniques could be adopted to develop [crop] varieties that can endure both biotic and abiotic stresses like high temperature, drought, salinity, pest and diseases,” he says. “Integrated pest and disease management along with choice of tolerant cultivars will help ensure good yield and avoid economic losses.”
“Creating an agricultural landscape which is more diverse and more resilient is something we really need to think about and implement more widely,” Bebber says.
Banner image: A fall armyworm on a maize leaf it has just destroyed on a farm in Kenya. Image by Jennifer Johnson/CIMMYT via Flickr (CC BY-NC-SA 2.0).
Agroecological solutions better than pesticides in fighting fall armyworm, experts say
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Raju, C., Pazhanivelan, S., Perianadar, I. V., Kaliaperumal, R., Sathyamoorthy, N. K., & Sendhilvel, V. (2024). Climate change as an existential threat to tropical fruit crop production—A review. Agriculture, 14(11), 2018. doi:10.3390/agriculture14112018
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