Joachim Offenberg and colleagues have this season transplanted colonies of forest ants to commercial orchards to see whether they will feed on caterpillars of the winter moth (Operophtera brumata) that would otherwise eat the trees' new foliage at a time when other predators have not yet become active.
Ants are believed to help fertilise the trees with their urine and faeces, and also release antibiotics including poisons to fungi via glands and bacteria on their bodies. Previous research has shown that disease in wild trees increases substantially when ants are removed from the area.
"Ants live in close communities where disease is a risk, so are able to produce antibiotics that can control fungal diseases," said Offenberg. "If ants deposit antibiotic substances in apple trees, it is expected to provide a reduction in the prevalence of diseases, including the dreaded scab. Thus ants could also help increase organic apples' quality."
He added: "We also know that the waste of weaver ants can be absorbed through trees' leaves and improve their nutrition. If the same is true of forest ants, they could potentially reduce fertiliser requirements in organic apple production." The trial will last until the end of next year.