Heliconius butterflies have a surprising aptitude for learning and remembering

In a new study published in the journal Current Biology, researchers have unveiled the remarkable ability of Heliconius butterflies to recall locations over extensive areas. 

This discovery provides the very first experimental evidence of spatial learning in butterflies, a capability previously unattributed to these insects.

Focus of the study 

While spatial learning has been documented among insects, the studies were often focused on ant and bee species, which have communal nesting habits. 

The recent study on Heliconius butterflies extends our understanding of spatial learning within the insect domain. It also suggests that intricate cognitive skills, such as utilization of spatial data, might be more pervasive among insects than was once believed.

Evolutionary behaviors 

“Heliconius butterflies have evolved a novel foraging behaviour amongst butterflies – feeding on pollen. Wild Heliconius seem to ascertain the position of steady pollen sources, subsequently establishing enduring ‘traplines,’ explained Dr. Stephen Montgomery from Bristol’s School of Biological Sciences.

“These traplines are memorized foraging trails revisited repeatedly over consecutive days, mirroring the efficient foraging techniques observed in some orchid bees and bumblebees.”

However, until this groundbreaking research, the spatial memory and learning aptitude of the Heliconius butterflies remained unknown.

How the study was conducted 

The researchers meticulously designed experiments spanning three spatial scales to imitate ecologically relevant behaviors of these butterflies. 

In one trial, the butterflies’ capacity to identify a food reward within a 1 m^2 grid consisting of 16 artificial flowers was gauged. Another test scaled up to a 3 m^2 two-armed maze to determine if the butterflies could associate food with either its left or right section, simulating multiple plants within a single area. 

The grandest of these experiments used vast outdoor enclosures at the Metatron in southern France, where the butterflies were tested on their ability to locate food in a 60 m wide T-maze, which corresponds to their foraging habits in the wild.

Future research 

Next, the researchers plan to discern if Heliconius butterflies, owing to their pollen-based diet, possess superior spatial learning capabilities compared to their non-pollen feeding relatives. 

Such insights would deepen the understanding of how an organism’s ecological dynamics might shape its cognitive evolution. 

The research team is also planning to explore the navigation mechanisms used by Heliconius. While visual stimuli, like panoramic vistas, seem vital for these butterflies, the potential usage of other cues like geomagnetic compass cannot be ruled out.

Thrilling results

“It’s been almost a century since the publication of the first anecdotal story on the spatial capabilities of these butterflies. Now we are able to provide actual evidence on their fascinating spatial learning. And this is just the beginning,” said Dr. Priscila Moura, based at Universidade Federal do Rio Grande do Norte.

Professor Marcio Cardoso from Universidade Federal do Rio de Janeiro said that his team is thrilled to find out that these insects can memorize the spatial location of food sources. “We are just beginning to get a glimpse of the kinds of information they gather about their surroundings.”

“It’s fascinating to learn about the complex behaviors that even familiar animals like butterflies express as part of their natural ecologies,” said Dr. Montgomery. “These species are extracting and processing diverse information from their environment and using them to perform complex tasks – all with brains a couple of millimeters wide.”

More about Heliconius butterflies 

Heliconius butterflies, often referred to as longwings or passion flower butterflies, are a captivating group of colorful butterflies native to the tropical and subtropical regions of the Americas, from South America to the southern parts of North America. 

These butterflies are distinguished not only by their vibrant patterns and colors but also by their unique biological and ecological attributes. 

Mimicry

Many species of Heliconius butterflies exhibit Müllerian mimicry, a form of mutualistic mimicry where two or more harmful species resemble each other. This allows them to share the cost of teaching predators that they are unpalatable.

Dietary habits

Unlike most butterflies that feed solely on nectar, some Heliconius species have evolved to feed on pollen as well. This diet provides them with amino acids, enhancing their longevity and reproductive capabilities.

Lifelong mating

Certain species of Heliconius butterflies are known to engage in a behavior called “pupal mating,” where males mate with female pupae just before they emerge as adults. After mating once, many Heliconius females will not mate again, storing the sperm to use over their lifetime to fertilize their eggs.

Warning colors

Their bright and contrasting color patterns serve as a warning to potential predators that they are unpalatable or toxic. This is a result of the toxins they accumulate from the passionflower leaves their caterpillars feed on.

Egg cannibalism

Some Heliconius caterpillars exhibit cannibalistic behavior. When a female butterfly lays her eggs on a passionflower that already has eggs, the newly hatched caterpillars might consume the other eggs for nutrients.

Cultural significance

Due to their vibrant colors and patterns, Heliconius butterflies have cultural importance in many of the regions they inhabit. They are often seen as symbols of transformation, beauty, and nature’s splendor.

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