Studies on the ecosystem functions of abandoned paddy fields: Clarifying the effects of pest predation

2023 Fiscal Year Final Research Report

• Project/Area Number: 20K06340
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 41050:Environmental agriculture-related
• Research Institution: Ryukoku University (2022-2023); Niigata University (2020-2021)
• Principal Investigator: Kishimoto Keiko 龍谷大学, 先端理工学部, 准教授 (80525692)
• Project Period (FY): 2020-04-01 – 2024-03-31
• Keywords: 生態系機能 / 耕作放棄地 / 捕食性節足動物 / 景観構造

Outline of Final Research Achievements

This study aimed to propose abandoned land management methods to enhance the pest control function of rice paddies. It focused on natural enemies such as 1) amphibians (Sado wrinkled frog) and 2) predacious arthropods such as spiders dwelling and building nets on plants in abandoned rice paddies in Sado City, clarifying their habitat conditions and diet within the abandoned fields. For 1), it was suggested that the frogs migrate to the abandoned fields depending on the season and use fields with water pools that are not mown as overwintering sites. Predation on pest species was also confirmed. For 2), it was shown that the number of spiders on plants had a positive correlation with the area of surrounding abandoned fields and was higher in wet abandoned fields. Results from DNA metabarcoding analysis of the spider's stomach contents indicated that the number of prey OTUs was higher in wet areas.

Free Research Field

昆虫生態学

Academic Significance and Societal Importance of the Research Achievements

本研究では、サドガエルが水田の害虫抑制に寄与することを示した。野外調査や操作実験の結果から、それらの個体群維持には、草刈りをしない粗放的な管理が可能であることを示した。捕食性節足動物群は分類群によって傾向は異なるものの、少なくとも植物上のクモ類密度を高めるためには、草刈回数を少なくすることや湿性の放棄地を残すことが有効であると示された。また、害虫抑制効果の観点からも、湿性の放棄地の維持が重要であると考えられた。本研究は、このように天敵群を維持するための具体的な草刈回数や管理対象の放棄地の状態を明らかにし、地域の放棄地管理につながる基礎情報を提供することができた。