Processes and driving factors of host shift and diversification in endophytic phytophagous insects

2023 Fiscal Year Final Research Report

• Project/Area Number: 20H03321
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Review Section: Basic Section 45040:Ecology and environment-related
• Research Institution: Kyoto University
• Principal Investigator: Kato Makoto 京都大学, 人間・環境学研究科, 名誉教授 (80204494)
• Project Period (FY): 2020-04-01 – 2023-03-31
• Keywords: leaf-miner / Agromyzidae / phytophagous insect / host shift / diversification / liverwort / hornwort / bryophyte

Outline of Final Research Achievements

Through extensive search for diversity of leaf-miners, I found remarkable diversity of agromyzid flies associated with bryophytes. While only one agromyzid species had been described in the world, in Japan I found 39 bryophyte-associated agromyzid species, all of which belongs to Phytoliriomyza, and 37 among 39 were described as new species. Among the 39 spp., 36 utilize liverworts, 3 utilize hornworts, and all were highly host-specific. Molecular phylogenetic analyses revealed that host shift from angiosperm to bryophytes had occurred once, and that repeated host shifts across bryophyte genera/species caused the thallus-miner diversity.

Free Research Field

生態学

Academic Significance and Societal Importance of the Research Achievements

これまで、食植性昆虫は被子植物の多様化に追随するように多様化したと考えられてきた。しかし本研究は、コケ植物を利用するハモグリバエ類が高い多様性をもち、しかもそれぞれの種が高い寄主特異性を持っており、寄主転換の繰り返しを伴う食植性昆虫の多様化が、被子植物上だけでなくコケ植物上でも起こったことを世界で初めて明らかにした。タイ類は油体に多くの二次代謝産物を含有しているが、油体が被食防衛に深く関わってきた可能性も示された。コケ食昆虫にはコバネガ類やシトネアブ類のような中世代起源のものが知られていたが、新生代に被子植物食からコケ食になった種群もあるという今回の発見は、植物食の進化に多くの示唆を与える。