DR’s nature program “Dyrenes Danmark” aired a segment on August 16, 2026, in which Danish researchers use forest ant nests in apple orchards as a pesticide-free way to protect trees from pests and disease.
According to DR, host Vicky Knudsen follows senior researcher Joachim Offenberg from Aarhus University into the field. Offenberg, who specializes in ants, has moved an ant nest into a fruit plantation for the program.
He explains that a single ant is fairly unintelligent, but that colonies develop what researchers call collective intelligence. Getting the queen along is essential, since she can produce more than a million workers during her life. Even after the nest is disturbed by the move, the ants quickly rebuild their society and begin patrolling the trees for prey.
Offenberg tells DR that the ants do more than eat pest insects. They have lived in dense societies for 100 million years and have a gland that secretes broad-spectrum antibiotics, alongside antibiotic-producing bacteria on their bodies. He describes the insects as a walking pharmacy that leaves these substances behind on apple trees, and says trees tended by ants show less apple scab and apple rot.
A press release from Aarhus University, issued in April 2026, states that ants inhibit at least 14 different plant diseases. The university points to antibiotic substances in the ants’ trails as the likely mechanism, and confirms earlier trials where relocated forest ants reduced scab and rot in an apple plantation.
From PhD project to subscription nests
The program also features biologist Ida Cecilie Jensen, who has written her bachelor’s thesis, master’s thesis and PhD on ants. Her PhD project won DR’s “Forskerfesten 2026” earlier this year, an event held with Dagbladet Information and Lundbeckfonden. She now runs her own company, renting out ant nests to fruit plantations on subscription.
Jensen says that once the nests are installed, growers avoid driving machinery and spraying, because the ants do the work. Since the insects need more energy than their prey provides, she installs dispensers with sugar water in the orchards. A 2025 profile in Berlingske described the company AgroAnt, which supplies nests together with the sugar dispensers, reducing the ants’ need to farm aphids.
Jensen adds that research shows the smell of ants alone can keep certain pest insects away. How strong that odor must be to deter pests is part of her ongoing research, she says in the program.
Project news published in December 2025 by ICROFS describes the MothStop project, in which forest ants are used in organic apple orchards against frost moth larvae and scab. ICROFS notes that cost-benefit analyses find established ant colonies both cheaper and more effective than pesticides. The work forms part of wider Danish research into lowering chemical use and costs for farmers.
