For highly social bee species, juvenile hormone (JH) and social cues are linked to increased expression of class-based social features. However, little data has been collected on the relationship between these variables and homologous features in non-social bees. To fill this gap in data, we studied the neuroanatomical response of Nomia melanderi, a non-social bee species, to endocrine and social treatments. Since N. melanderi is a non-social bee with pre-adaptations to sociality, such as brood care and aggregative nesting habits, its responses to hormone treatment and social cues can be used to model how neural plasticity in non-social ancestors of highly social bee species may have played a role in social evolution. Specifically, we measured volumetric difference in mushroom body structures, which are known to function in social cognition in social bees, in response to our treatments. Brains from the six treatment groups were dissected and imaged using confocal microscopy techniques. By scaling the actual distance in an image to its pixel density, reliable measurements of volume are produced from evenly spaced cross-sections of N. melanderi brain. Since data collection for the current phase of the project is still underway, it’s premature to make any conclusion about how JH and social cues influence neural plasticity in N. melanderi. However, the results of our experiment are likely to provide unique insights into the evolution of sociality in bee species generally.1
Tirrell, Justin; Hagadorn, Mallory A.; Johnson, Makenna M.; and Kapheim, Karen M., "Tracing Brain Structures of Alkali Bees to Investigate Endocrine and Social Effects on Neural Plasticity" (2017). Biology Posters. Paper 194.