Ant responses to social isolation look like those of humans

Ants respond to social isolation in a similar way to humans and other social mammals. A study by an Israeli-German research team revealed changes in the social and hygienic behavior of ants isolated from their group. The research team was particularly surprised by the fact that immune and stress genes in the brains of the isolated ants were downregulated. “It makes the immune system less efficient, a phenomenon that also occurs in the socialization of humans – especially currently during the COVID-19 crisis,” said Professor Susanne Foitzik, who led the study at Johannes Gutenberg University Mainz ( JGU) was, said. The study on a species of ant that originated in Germany was recently Molecular ecology.

The effects of isolation in social insects that have so far been little studied

Humans and other social mammals experience isolation from their group as stressful, and have a negative impact on their overall well-being and physical health. “Isolated people become lonely, depressed and anxious, develop addiction more easily and suffer from a weakened immune system and a weakened general health,” added Professor Inon Scharf, lead author of the article and collaborating partner of the Mainz Research Group in Tel Aviv, University. in Israel.

Although the effects of isolation have been extensively studied in social mammals such as humans and mice, less is known about how social insects respond in similar situations – even though they live in highly developed social systems. Ants, for example, live their entire lives as members of the same colony and are dependent on their colony mates. The working ants abandon their own reproductive potential and devote themselves to feeding the larvae, cleaning and defending the nest and seeking food, while the queen does little more than lay eggs.

The research team looked at the effects of social isolation in the case of ants of the species Temnothorax nylanderi. These ants inhabit cavities in acorns and hide on the ground in European forests and form colonies of several dozen workers. Young workers engaged in the care of hatcheries were taken separately from 14 colonies and kept in isolation for different periods, from one hour to a maximum of 28 days.

The study was conducted between January and March 2019 and highlighted three specific aspects in which changes were observed. After their isolation, the workers were less interested in their adult colony mates, but the length of time they spent in bar contact increased; they also spent less time taking care of themselves. “This reduction in hygienic behavior may make the ants more susceptible to parasites, but it is also a characteristic of social deprivation in other social organisms,” explains Professor Susanne Foitzik.

Stress due to isolation adversely affects the immune system

While the study revealed significant changes in the behavior of isolated insects, its findings regarding gene activity were even more striking: many genes related to the function of the immune system and stress response were downregulated. In other words, these genes were less active. “This finding is consistent with studies on other social animals that show a weakening of the immune system after isolation,” said Professor Inon Scharf.

The discovery by the team of biologists led by Professor Susanne Foitzik is the first of its kind, combining behavioral and genetic analyzes on the effects of isolation in social insects. “Our study shows that ants are just as affected by isolation as social mammals and suggest a general association between social well-being, stress tolerance and immune competence in social animals,” Foitzik concluded, summarizing the results of the Israeli-German study. Foitzik is also working with her Israeli partner Professor Inon Scharf and co-author and group leader Dr Romain Libbrecht of JGU on a new joint project on the fitness benefits and molecular basis of spatial learning in ants, funded by the German Research Foundation (DFG ).