Effects of Early Developmental Isolation on Social Behavior in Bumblebees, Bombus impatiens

Abstract

Early life experiences that come from social and environmental stimuli are critical to the development of the brain. As shown by studies of orphaned children and animal experiments, organisms are unable to develop full brain functions in adulthood if they are deprived of natural experiences early on. While the effects of somatosensory deprivation have been widely investigated, social deprivation, which may be more relevant to social isolation in humans, has been more difficult to study due to the lack of social complexity in model organisms. However, bumblebees offer a unique opportunity to study social development as they show high degrees of behavioral plasticity, live in socially structured colonies, and share molecular mechanisms that shape neural development with vertebrates. My thesis uses bumblebees in order to examine the behavioral differences that occur from social isolation by comparing isolated bumblebees to colony-raised equivalents in terms of exploratory behavior and indicators of sociability. Pupae were collected 24 hours post-eclosion and isolated for nine days, the duration of adult brain development in bumblebees. After first rounds of testing, a cohort of isolated bees were also returned to their natal colonies and retested after five days of “typical” social exposure in order to test for resilience, or recovery from deprivation. I observed that isolated bees showed lower levels of activity as well as lower motor function than colony-raised bees and also had impaired recognition capabilities. No recovery in behavior was made despite the five-day restoration of social input at 10 days old.