Agricultural pests that devour major food crops are moving north, becoming more widespread as the climate warms, new research warns.
Milder winters could threaten crop yields as herbivorous insects spread north and become more voracious, the researchers say.
The fall armyworm ( Helicoverpa zea ) is among the most common agricultural pests in the US, devastating crops such as corn, cotton, soybeans and other vegetables. It winters underground and is not known to survive in states beyond a latitude of 40 degrees north (which extends from Northern California through the Midwest to New Jersey), but that is changing as the soils warm. and spread to new areas, according to research. . administered by North Carolina State University.
The report follows for research at the University of Washington in 2018 which found that 2°C (3.6°F) of warming would increase the number and appetite of insects worldwide, causing them to destroy 50% more wheat and 30% more corn than they do now. Rising heat stress is already taking a toll on yields, with staple crop harvests in Europe this year as a result of heat waves and drought.
Pest invasions have serious implications for food safety
“As the climate changes, hibernation zones are likely to shift northward,” said co-author Anders Huseth, an entomologist at North Carolina State University. “This is the canary in the coal mine for agricultural pests.
“Understand what is happening with [el gusano cogollero] It is very important for agricultural producers.” Other pests that can spread north in a similar way include the fall armyworm, green clover, Soy and the velvet bean caterpillar.
The researchers created maps that show three distinct geographic zones in the US: the “southern range”, where fall caterpillars survive the winter, a “transition zone”, where they can survive the winter, and the “northern range”, where they generally cannot survive the winter. because soil temperatures drop below zero.
The researchers already knew that warmer winter soils meant that soil-dwelling insects were more likely to survive. Using four decades of soil temperatures and fall armyworm monitoring data, the researchers predicted future pest distribution.
The southern mountain range has grown by 3% since 1981 and is expected to double in size by the end of the century as other areas get smaller, according to the article, published in Proceedings of the National Academy of Sciences . Fall armyworm moths can disperse up to 600 miles (1,000 km) using seasonal winds, meaning they can spread quickly if conditions are good.
In the coming decades, the model illustrates that this insect could expand its hibernation area in the US corn belt to Ohio, Indiana, Illinois, Missouri and Iowa. In Minnesota, for example, no fall caterpillars have survived its harsh winters, but models suggest the entire state will be in the transition zone by the end of the century.
Increased use of pesticides and lower yields
“If intensive corn production also doesn’t shift north with climate change, we expect the fall armyworm to become a more prevalent and important problem in these states,” said Dr. Douglas Lawton, former postdoctoral fellow at North Carolina State University and co-author of the paper.
“Organic growers have a big challenge controlling this pest and often accept significant crop losses when infestations are high,” he said.
Monitoring soil temperature can help predict the spread of pests, helping farmers to control them more effectively, the report suggests. Huseth said: “We would like to create a better prediction tool for this pest, along with a risk prediction model, to provide growers with better information about the spread of pests. Success here can reduce costs for farmers and pesticides on the environment.”
By Phoebe Westton. Article in English