open access

https://hdl.handle.net/2115/66511

Social-Organization Shift in the Sweat Bee, Lasioglossum baleicum (Hymenoptera, Halictidae), Corresponds to Changes in Foraging Activity of the Predatory Ant Tetramorium tsushimae (Hymenoptera, Formicidae)

英語

Ants

2011-01-01

California State University

Sociobiology

58(1)

241-250

Ecological factors, such as predation pressure or survival rate, affect social structure (e.g., gyny or founding modes) in social insects. Multiple females may cooperatively found a nest under severe ecological conditions. In bivoltine sweat-bees, most nests in the first reproductive period include a single female, but nest organization changes to cooperative in the second period. This fact predicts low predation pressures during the first period. However, few studies have examined corresponding changes between nest organization and predation pressures in social insects. Here, we compare the predation pressure between the two reproductive periods by using a sweat bee, Lasioglossum baleicum, that shifts the social organization from solitary to cooperative between the two reproductive periods.We recorded foraging activities of the predatory ant, Tetramorium tsushimae, during the whole reproductive season of L. baleicum and compared those between the first and second periods. The foraging activities of T. tsushimae were low in the first season but rapidly increased with the start of the second season. The foraging activities vary among bee populations depending on temperature conditions. The foraging activities were high during the cooperative period, suggesting that cooperation is a counter strategy to a high risk of predation. Further investigations on relationships between nest organization and strength of predation will bring us deeper insights into the effects of predators on the evolution of cooperation.

学術雑誌論文

Version of Record

0361-6525

0361-6525

AA00443211