Social interactions and behavioral context in a largely solitary bee, Lasioglossum (Dialictus) figueresi (Hymenoptera, Halictidae)

Understanding the development of behavioral differences among group members is a key to understanding social evolution or its loss. Social sweat bees (Halictinae) show distinct behaviors related to social competition and cooperation, and the frequencies of these behaviors differ for different functional groups (workers, guards, queens). These behaviors occur in solitary halictine bees under artificial conditions in a circular arena involving pairs of interacting bees. Reproductively active bees were tested, as were reproductively inactive bees, both from different nests and the same nests within a nesting aggregation. Among reproductively active bees, the first bee to display aggressive behavior more frequently had larger ovaries, and the first bee to withdraw from a social encounter more frequently had smaller ovaries. Body size did not influence these outcomes. The first bee placed in the arena was more likely to adopt an aggressive posture when bees first met, and the second bee placed in the arena was more likely to withdraw. Among reproductively inactive bees. females paired with a bee taken from the same nest were less likely to be aggressive than a bee paired with one from a different nest, suggesting familiarity (possibly kinship) can modulate aggressive behavior.