Intrinsic and Extrinsic Factors Shaping Behavior in Social and Solitary Halictid Bees

Abstract

Social behaviors are integral to the interactions among numerous species, supporting dynamics between individuals as well as among the functioning of populations. However, it is not well understood how internal and environmental factors interact to shape social behavior, and what underlies variation in responses to social situations. This study builds upon previous evidence of queen control of expression of worker behavior in halictid bees, and analyzes behavioral circle tube assays of closely-related social (Augochlorella aurata) and solitary (Augochlora pura) halictid species to determine intrinsic differences between the two species. The study examines first the effects on behavior of a bead coated in the cuticular hydrocarbons (CHCs) of each species mimicking dominant queen backing behavior in a solo circle tube assay, to understand the role of chemical cues and behavior of an unfamiliar conspecific on individual behavior. Secondly it investigates the effects of juvenile hormone (JH), shown to be a component of reproductive development and caste differences in Hymenoptera, on behavior across species through a paired circle tube assay, in which two individuals of the same species, one treated with precocene, an inhibitor of JH synthesis, and one treated with precocene and JH were paired in a circle tube. In the first experiment, it was found that time of season significantly affected c-posture behavior in A. pura, and a similar trend was observed in A. aurata, consistent with previous findings of other Augochlorini bees. The second experiment found that three behaviors (pass, c-posture, and nudge) were significantly affected by JH treatment.