Ants could help apple growers cut pesticide use

Ants could help protect apple trees from pests and diseases, potentially reducing the need for pesticides, DR reports. Researchers say the insects eat harmful pests and produce antibiotics that may help prevent common apple diseases.

Joachim Offenberg, a senior researcher specialising in ants at Aarhus University, says ants display what is known as collective intelligence when they work together in colonies.

As part of the programme Dyrenes Danmark, Offenberg moved an anthill to an orchard. The queen must be moved with the colony because she can produce more than one million workers during her lifetime.

Although the move temporarily disrupts the colony, the ants quickly rebuild their society and begin patrolling the trees for prey. They eat many of the insects that attack apples.

Offenberg says ants may also have developed an important defence against disease after living in densely populated colonies for 100 million years. They have a gland that produces broad-spectrum antibiotics, while bacteria on their bodies also produce antibiotics that can combat disease.

“We can see that apple trees cared for by ants have fewer diseases, such as apple scab and fruit rot,” Offenberg says.

Biologist Ida Cecilie Jensen has also researched ants as an ecological alternative to pesticides in fruit growing. Her doctoral project won the 2026 Forskerfesten competition, organised by DR in cooperation with Dagbladet Information and the Lundbeck Foundation.

Jensen now runs a company that rents out anthills to orchards on a subscription basis. Once the colonies are installed, growers no longer need to use machinery or spray the trees, she says, because the ants do the work.

The ants need more energy than they can obtain from the insects they eat, so Jensen provides them with sugar-water dispensers. Research also suggests that the smell of ants alone may deter some insect pests. Jensen says her company is studying how strong this effect can be.