‘Borrowed time’: crop pests and food losses supercharged by climate crisis | Food security

The destruction of food supplies by crop pests is being amplified by the climate crisis, and losses are expected to increase, analysis shows.

Researchers said the world was lucky to have so far avoided a major shock and was living on borrowed time, with measures needed to diversify crops and boost the pests’ natural predators.

The world’s major crops, wheat, rice and corn, are expected to see losses from pests increase by about 46%, 19% and 31% respectively when global warming reaches 2°C, scientists said.

Global warming helps insects such as aphids, leafhoppers, stem borers, caterpillars and locusts thrive. Greater heat allows pests to grow more quickly, produce more generations each year and attack crops for longer as winters shorten. Rising temperatures also help pests invade places farther from the equator and on higher ground that were previously too cold.

As a result, climate-driven pest proliferation will be worst in temperate regions, such as Europe and the United States, the researchers said. Temperatures may already have reached a limit for some insects in the tropics, they said, although cutting cropland to rainforests further favors the pests.

The movement of pests is also accelerating through food exports through global trade networks. At the same time, the destruction of natural habitats and the massive use of pesticides and fertilizers are crippling the pests’ natural predators, while the expansion of agricultural land is creating new areas infested by crop pests.

Pests and diseases destroy around 40% of global agricultural production, “creating a major challenge to global food security”, the scientists said. The direct impact of the climate crisis on wheat, rice and corn is expected to reduce yields by 6 to 10% for every 1°C of global warming.

“The world is focused on these major grains – wheat, rice, corn, soya – and it’s a very simplified and vulnerable system,” said Professor Dan Bebber, of the University of Exeter, UK. Monocultures – large areas growing a single variety of crop – could be wiped out by a single pest. “We’ve been lucky so far. But with the multiple threats of climate change and the many pests and diseases, we need to start thinking about a resilient system to feed everyone.”

“The green revolution, through simplification, plant breeding, massive use of fertilizers, fungicides and pesticides, saved millions of people from hunger,” he said. “But this was in a world where warming was not rapid, where parasites and pathogens were just beginning their journey globally, and where negative impacts on soils and biodiversity were not coming back to us. We were living on borrowed time, but we are heading into a critical period and we need to do things differently.”

The analysis, published in the journal Nature Reviews Earth & Environment by Bebber and international colleagues, is a conservative assessment of increased pest damage to crops due to the climate crisis because it focuses on insects and major grain crops, and does not include microbial diseases, fungi and nematodes or the full range of cultivated foods.

Crop pests have evolved alongside the plants they target, which provide high-quality food sources and can reproduce and disperse quickly. They have often developed resistance to pesticides.

The use of fertilizer and irrigation in intensive agriculture improves the quality and quantity of plants, meaning that crop pests are much less affected by the destruction of natural habitats that has led to the collapse of many wild insect populations.

Rising temperatures can cause sudden impacts, the analysis shows, with slight increases in temperature allowing insects to produce another generation over the course of a season. “When the Colorado potato beetle manages to go through another life cycle, it causes big problems,” Bebber said.

The climate crisis is increasing heat levels but also causing greater rainfall in places. These can eliminate small pests, according to the analysis, but wetter conditions benefit pests overall. Firstly, as small creatures, insects are at high risk of drying out, and secondly, the evaporation of rainwater cools the local environment, protecting them from the heat.

Scientists said that environmentally friendly protection against pests can be achieved by restoring natural habitats to increase the number of parasitic wasps and other natural predators of pests.

“Our increasingly simple agricultural systems are vulnerable but are maintained by fungicides and pesticides, which is OK as long as they work,” Bebber said. “But we are faced with evolving pesticide resistance and we now need to think seriously about whether we want to use diversification as a strategy to help make our systems more resilient.”

Diversification could also include growing different varieties of a crop together and integrating agriculture and livestock. Examples of the latter include traditional systems in Japan where ducks eat the snails and insects that attack rice and in the United Kingdom where sheep grazing on winter wheat remove leaves affected by fungal disease.

The analysis also indicates that artificial intelligence can strengthen crop protection by analyzing terrain and weather data to predict infestations and develop strategies to deal with them.