It is comparable to going to the chemist. Sick grey-black slave ants (Formica fusca), a common species of wood ant in Europe, look for their medicine in a targeted manner. "We were able to see that the ants that were exposed to a fungal pathogen changed their diet, which was more enriched with aphids," summarises Jason Rissansen, PhD student at the Institute of Biology at the University of Graz.
To this end, the ants were offered food in three different aphid concentrations. As they were infected, they consumed food with a higher proportion of crushed aphids during the acute phase of the infection. Hydrogen peroxide, which is contained in the tiny animals and has a disinfectant effect, could possibly play a key role in combating the disease. "The mortality rate among the diseased ants was significantly reduced thanks to the change in composition," reports Rissanen, a member of the team led by zoologist Dalial Freitak. "Once the insects were healthy again after a few days, they stopped eating the aphid diet of their own accord."
Jason Rissansen is leading author of the international study, which was conducted jointly with the Universities of Helsinki and Oulu (both Finland), Wageningen University (Netherlands) and the Julius Kühn Institute in Quedlinburg (Germany) and recently published in the journal Biology Letters.