The mechanism determining the density of generalist predators in rice-paddy dominated landscapes: a food resource-mediated indirect effect

2015 Fiscal Year Final Research Report

• Project/Area Number: 25850237
• Research Category: Grant-in-Aid for Young Scientists (B)
• Allocation Type: Multi-year Fund
• Research Field: Environmental agriculture(including landscape science)
• Research Institution: National Institute for Agro-Environmental Sciences
• Principal Investigator: Baba Yuki 国立研究開発法人 農業環境技術研究所, その他部局等, 研究員 (70629055)
• Project Period (FY): 2013-04-01 – 2016-03-31
• Keywords: 景観構造 / 広食性捕食者 / アシナガグモ / 環境保全型農法 / ユスリカ / 間接効果 / GIS / 捕食率

Outline of Final Research Achievements

I tested the potential effect of landscape structure on the density of generalist predators (Tetragnatha spiders) in rice paddy fields mediated by food resource availability. I surveyed abundances of Tetragnatha spiders and their potential prey in 20 rice fields along a gradient from simple arable-dominated to forest-rich landscapes in Tochigi prefecture, and analyzed the relationships among landscape structure, spider abundance and prey availability. Results of landscape analysis showed that forest areas within a 200 m around study fields positively affected the abundance of spiders. Path analysis revealed that the increase in spider abundance was attributed to the increase in abundances of chironomid flies that are important alternative prey of the spiders. On the other hand, PCR-based gut-content analysis of spiders failed to detect the increase in predation rate of chironomid flies by spiders. Further improvement is needed in the evaluation method.

Free Research Field

生態学