Sensory cues and memory in Lepidopteran mud puddling behavior

Abstract

Puddling is a form of supplemental feeding for nectivorous Lepidoptera to acquire necessary mineral nutrients, primarily sodium, that are otherwise absent from their nectar diets. For many species sodium is important for growth, nervous system function, and egg production. However, the mechanisms through which Lepidoptera locate puddling sites is unknown. I investigated three potential factors influencing puddling site selection: visual cues from landscape contrast, olfactory cues from bacterial volatiles, and memory. Knowing the factors that influence lepidopteran puddling site selection can help us better understand how they find the resources necessary to survive and reproduce, as well as provide insight to the learning and memory capacities of Lepidoptera. Landscape contrast had a significant effect on lepidopteran puddling site selection, with butterflies on average choosing spots lighter than the surrounding area. Temperature and shade also affected butterfly puddling, with butterflies across families showing a preference for warmer sites in direct sunlight. Between families, there were significant differences for puddling preferences for sites with certain temperatures and water contents. It is unclear if Lepidoptera use scent to find puddling sites. Overall, returns to specific puddling sites were rare and Lepidoptera do not seem to be using short term memory to relocate spots, but more data would need to be conducted to say anything conclusive.