Summary: Scientists have shown for the first time that Heliconius butterflies can learn and remember spatial locations. This experimental evidence demonstrates that these butterflies use spatial information to locate and revisit reliable food sources, a behavior that supports their long-distance foraging strategy known as traplining.
Until now, experimental work on insect spatial learning has emphasized social insects such as bees and ants. These new findings indicate that advanced spatial learning may be more widespread across insects than previously recognized.
Key Facts:
- This study presents the first direct experimental evidence of spatial learning in any butterfly or moth species.
- Heliconius butterflies learn the locations of dependable pollen sources and form long-term “traplines”—consistent, efficient routes along which they revisit food sources across days.
- Researchers tested spatial memory across three ecologically relevant spatial scales, showing that Heliconius can memorize locations of rewards from small local patches up to distances approximating their natural foraging ranges.
Source: University of Bristol
Heliconius butterflies are capable of spatial learning, researchers have discovered.
Published today in Current Biology, the study offers the first experimental confirmation that any butterfly or moth species can learn and remember spatial locations. The results also indicate that Heliconius butterflies can form spatial memories over large areas, consistent with the demands of traplining—repeated foraging within a home range that can cover several hundred square metres.
Much past research on insect spatial learning has centered on social species that navigate to and from a communal nest. By demonstrating spatial learning in a non-social butterfly, this study broadens our understanding of how complex cognitive skills—like using spatial information—have evolved across insects.
Dr Stephen Montgomery of the University of Bristol’s School of Biological Sciences, a senior author on the paper, explains: “Heliconius butterflies have evolved a unique feeding strategy among butterflies—pollen feeding. In the wild, they appear to learn where reliable pollen sources are and establish long-term traplines.”
Traplines are learned foraging routes: animals repeatedly visit the same sequence of food sources over successive days. This strategy is an efficient way to exploit scattered resources and is seen in some bees and orchid bees. Prior to this study, the spatial learning abilities of Heliconius—or any butterfly—had not been experimentally tested.
The research team ran controlled spatial learning experiments at three progressively larger scales to match behaviors Heliconius experience in nature. First, butterflies were tested on a 1 m² grid with 16 artificial flowers to simulate foraging within a single resource patch. Next, researchers presented a two-armed maze covering 3 m² to determine whether butterflies could learn to associate reward locations with the left or right side—mimicking choices among multiple nearby plants. Finally, in large outdoor enclosures at the Metatron research facility in southern France, the team used a T-maze spanning 60 m to evaluate whether the butterflies could learn reward locations over distances approaching those used during wild foraging.
Results from these experiments indicate that Heliconius butterflies can form and use spatial memories across these scales. The authors plan follow-up experiments to compare spatial learning in Heliconius with closely related species that do not feed on pollen. Those comparisons will help determine whether the evolution of pollen feeding drove enhanced spatial cognition.
Researchers also aim to uncover which navigational cues Heliconius use. Visual panorama cues are likely important, but butterflies might also use the sun or geomagnetic information to orient over larger distances.
“It’s been nearly a century since the first anecdotal observations suggested these butterflies have impressive spatial abilities,” says Dr Priscila Moura, co-lead author at Universidade Federal do Rio Grande do Norte. “Now we have experimental evidence of their spatial learning, and this is only the beginning.”
Dr Fletcher Young, co-lead author at the University of Bristol, adds: “We present the first direct evidence of spatial learning in a butterfly, and our findings align with their natural foraging patterns, showing more effective learning across larger distances.”
Prof Marcio Cardoso, co-supervisor at Universidade Federal do Rio de Janeiro, comments: “Discovering that these insects can memorize the spatial location of food sources gives us a glimpse into how much environmental information they gather and use.”
Dr Montgomery concludes: “It is fascinating to uncover the sophisticated behaviors that even small-brained animals like butterflies use in their ecosystems. These species extract and process diverse environmental cues to perform complex tasks, all with brains only a few millimetres in size.”
About this spatial learning research news
Author: Victoria Tagg
Source: University of Bristol
Contact: Victoria Tagg – University of Bristol
Image: The image is credited to Neuroscience News
Original Research: Open access. “Rapid expansion and visual specialisation of learning and memory centers in the brains of Heliconiini butterflies” by Stephen Montgomery et al., Nature Communications
Abstract
Rapid expansion and visual specialisation of learning and memory centers in the brains of Heliconiini butterflies
Evolutionary changes in the abundance, diversity and connectivity of neural cell types shape brain structure and create the foundation for changes in behaviour. While it is understood that investment in specific sensory brain regions often reflects the ecological importance of particular senses, how selection acts on integrative brain centers has been harder to resolve.
This study provides evidence for considerable, mosaic expansion of an integrative brain center among closely related butterfly species, expansions that cannot be explained simply by changes in primary sensory input regions. By compiling new neural trait datasets across the Neotropical Heliconiini tribe, the authors identified several major evolutionary enlargements of the mushroom bodies—central structures critical for insect learning and memory.
Members of the genus Heliconius, which uniquely feed on pollen and show derived foraging behaviors that depend on spatial memory, exhibit the most pronounced mushroom body enlargement. This neural expansion is associated with increased visual processing capacity, greater precision in visual discrimination, and improved long-term memory.
Overall, the results indicate that selection for novel behaviors and enhanced cognitive abilities can act through expansion and localized specialization of integrative brain centers.