Heliconiini butterflies display flight behaviours reminiscent of orientation flights when using new floral sources

Despite their small brains, many insects form long-term memories of the
spatial distribution of resources. To support this, some species display
‘orientation’ flights to increase capture of landscape cues around novel
resources. The role of orientation behaviour in spatial learning has been
broadly explored in Hymenoptera, which are well known to navigate between
their nests and floral resources. Here, we describe exaggerated flight
behaviours expressed in the foraging context in Heliconiini butterflies,
resembling orientation behaviours in Hymenoptera. Heliconiini butterflies
are of particular interest as they include the genus Heliconius, which is
reported to have a greater capacity for spatial memory in association with
a novel dietary strategy of pollen feeding, including formation of stable
foraging routes. We hypothesised that these flight behaviours we observe
may provide a strategy to memorize the location of floral resources. We
compared Heliconius and non-Heliconius butterflies to evaluate this
ability in pollen and non-pollen-feeding Heliconiini species. We
characterized three behavioural patterns that are directed towards a new
floral resource: circle flights, hovering, and feeding bouts. Although all
Heliconiini studied displayed these patterns, Heliconius spent more time
performing these flight patterns, in particular hovering before landing.
We suggest that these behaviours could provide the context in which
individuals acquired sensory information to guide future foraging events,
and our data indicate greater emphasis on this process during memory
formation. Our findings of behaviours reminiscent of orientation flights
in Heliconiini butterflies provide new avenues of research on how spatial
learning and memory have converged between Lepidoptera and Hymenoptera.