Extinction of Innate Floral Preferences in the Generalist Solitary Pollinator Eristalis tenax.

Abstract

Innate behaviours allow solitary animals to complete essential tasks in the absence of social learning. However, we know little about the degree to which ecologically relevant innate preferences can change, and a complete extinction of innate preferences has rarely been shown. The hoverfly Eristalis tenax, a solitary generalist pollinator, is an ideal model for studying innate behaviour in a naturalistic context because its survival depends on the innate ability to identify flowers across many habitats, which could necessitate both learning and unlearning floral objects. Innate behaviour in E. tenax has previously been considered inalterable, but we hypothesised that E. tenax could modulate their innate behaviour after training to a multimodal object derived from chemical and visual cues previously shown to be attractive to hoverflies in field and laboratory assays. To test this, we examined whether E. tenax can extinguish an innate proboscis extension response (PER) to a floral object after undergoing aversive absolute conditioning with quinine, and if flies can acquire PER to an innately unattractive object using sucrose as reinforcement. Finally, we assessed long-term memory retention of these learned behaviours. Here, we report a complete extinction of the PER to an innately attractive floral object following aversive training. Eristalis tenax can also acquire PER to an innately unattractive object after appetitive training. Flies can retain these memories for days after training, and aversive memories last longer than appetitive memories. Ultimately, these findings improve our understanding of how animals integrate innate and learned behaviours to navigate the uncertainties of dynamic objects found in their natural environment.