Summer Research

* Student(s): Rebecca Parkhurst , Reagan Sayles
Advisor: Herman Lehman

Title: Neurohormonal Control of Aggression in Solitary and Social Insects


Insects are a remarkably diverse group of animals and inhabit essentially every environment on earth. In addition, many insects live in highly social communities, where community members display highly cooperative behaviors essential for the success of the group (e.g. honey bees) (Alcock, 1975). In contrast, other bees are solitary and do not exist in large communities. They build nests in the ground, cracks and crevices and support only their own offspring (

We suspect that social insects are more aggressive animals based on their relatively large investment into their community structure. On the other hand, solitary insects appear be less aggressive as they have less invested in their community structure and nest. Solitary bees are capable of stinging but will only sting if they are trapped or threaten. (

Studies of Kravitz and colleagues have shown that hormones play a fundamental role in aggressive behavior in another arthropod, the America lobster. More specifically, exogenous octopamine and serotonin generate dominant and subordinate postures (Livingstone, et al Science 76, 1980). In this study, we have begun to test the notion that hormones underlie aggressive behavioral differences in social and solitary insects.

To test our hypothesis we have examined the brain structure and octopamine levels in the brains of honey bees (social insect) and carpenter bees (solitary insects). The levels of octopamine were variable and did not appear to be different between the two insects, however, we cannot discount variations in handling. Histological examinations of the nervous systems of these insects are continuing. In summary, the large differences in the behaviors of these closely related bees strongly suggest large differences in nervous system function. This study will continue to explore the neurobiological underpinnings of aggression in solitary and social bees.

Student stipend support provided by NSF/STEP.