10 2 / 2022 // LEOPOLDINA / NEWS
“ More respect for nature and its smallest creatures ”
Leopoldina member Lars Chittka on the sensory perception and psychology of insects
The new members of Class II met in May for the Life Science Symposium at the Leopoldina in Halle ( Saale ). The evening lecture , which was again open to the public , was given by Lars Chittka ML . In the interview , the biologist , who specialises in the sensory perception and psychology of animals , talks about his research .
Social insects are traditionally viewed as reflex-driven individuals that are able to build complex nests and organise efficient division of labour , but which are individually stupid . Is this view correct ? Lars Chittka : Following new findings about the intelligence of insects , this historical opinion must be revised . We were able to prove , for instance , that bees can count and recognise images of human faces . Bumble-bees are even capable of using simple tools . We are researching the question of whether a form of consciousness can be found in bees – in other words whether they can think and feel .
How would you define ‘ think ’? Chittka : Thinking is a kind of inner world which happens within a brain . We have seen that bees are able to flexibly access autobiographical memories and plan for the near future . They solve tasks in a way that cannot be simply explained by trial and error , but by exploring the desired outcome by thinking and understanding . These are things that ten years ago nobody would have thought possible .
What experiments did you develop to find this out ?
Bumble-bees quickly learn how to pull a thread in order to access nectar .
Image : Sylvain Alem , Lars Chittka
Chittka : One of our experiments consisted of a large container with nectar being placed underneath a glass table . Bumblebees had to pull at a thread in order to access the nectar . This is the type of intelligence test usually performed to test primates or birds . Bumble-bees learnt to do this quickly , and they were even able to imitate other bumble-bees behaving in this way .
What does an insect feel ? Chittka : We were able to show that surprising rewards trigger an “ optimistic state of mind ” in bumble-bees , causing them to show spontaneous curiosity in the face of new stimuli . Attacks by predators can induce a negative state of mind . There are spiders that sit on flowers in order to catch pollinating insects . We imitated this in the laboratory and designed a plastic model of a spider with a mechanism that briefly held onto a bumble-bee before releasing it . The bumble-bee ’ s behaviour changed fundamentally : The bumble-bee seemed more nervous and more ready to take flight from an existent threat , even from a flower that did not contain a spider . It looked like post-traumatic stress disorder .
How sure can you be that this kind of assumption is accurate ? Chittka : It is always difficult because there is no formal proof of an animal ’ s emotions . We have to use our common sense and base our arguments on probability to corroborate observations using physiological or neuronal studies in order to prove that this kind of adaptive behaviour also makes sense for animals . If all of that is correct , it becomes quite probable that we are observing emotional states here . Nature does not indulge in equipping animal species with psychological behaviours that just seem like they are based on emotions .
What conclusions does this bring you to with respect to the protection of insects ? Chittka : We assume that bees know from experience that they suffer as a