Heliconius butterflies are capable of spatial learning, scientists have discovered. The findings, published in Current Biology, also suggest Heliconius butterflies may be able to learn spatial information at large scales, consistent with the apparent importance of long-range spatial learning for traplining, which involves foraging within a home range of a few hundred square meters.
Spatial learning is known in insects, but much of the research has focused on ant and bee species which live socially in a communal nest. This study provides the first direct evidence of spatial learning in butterflies or moths, and suggests that complex learning skills, such as the use of spatial information, may be more common in insects than previously thought. Dr. Stephen Montgomery of the University of Bristol’s School of Biological Sciences, a senior author, explained, “Heliconius butterflies have evolved a novel foraging behavior among butterflies—feeding on pollen … Wild Heliconius appear to learn the location of reliable pollen sources and establish long-term ‘traplines’.”
The team conducted spatial learning experiments in Heliconius butterflies over three spatial scales representing ecologically-relevant behaviors. First, they tested the ability of Heliconius to learn the location of a food reward in a 1 m2 grid of 16 artificial flowers, representing foraging within a single resource patch. Second, they increased the spatial scale and tested whether Heliconius could learn to associate food with either the left or right side of a 3 m2 two-armed maze, representing multiple plants at a single locality. They then increased the distances again and, using large outdoor cages at the Metatron in southern France, tested if Heliconius could learn the location of food in a 60 m wide T-maze, representing foraging between localities and approaching the scales over which wild Heliconius forage.
Now the team plans to test whether Heliconius are more proficient spatial learners than closely related species that don’t feed on pollen. This would help to reveal how the evolution of enhanced cognitive abilities can be shaped by an animal’s ecology. Additionally, the research group aims to uncover the mechanisms by which Heliconius navigate, which are unknown. Visual cues, such as panoramic views, are believed to be important for Heliconius, but they may also rely on other cues such as a sun or geomagnetic compass.
