沖縄県からの特定外来種ハヤトゲフシアリの根絶宣言/ Declaration of Eradication of the Invasive Species, the Browsing Ant Lepisiota frauenfeldi, from Okinawa Prefecture
- 3月12日
- 読了時間: 3分
更新日：3月17日
ようやくこの日が来ました！2020年に、那覇市の国道で定着が確認されたハヤトゲフシアリLepisiota frauenfeldi。6年を経て、2026年3月12日、ついに根絶宣言までたどり着きました。OIST時代からこの外来アリの防除にはずっと関わりながら、6年経って今では外来生物コンサルタントという名の独立研究者。OIST、環境省、そして現在のRyukyu Nature Positive（琉球ネイチャーポジティブ）と、報道に出るたびに異なる肩書で発言していて、自分にとっては経歴記録のようです(^_^;)
このアリが見つかったとき、
「いつか根絶して一緒に記者会見やりましょう！」
と協力をお願いしたのを思い出します。
たくさんの人たちに協力してもらい、支えられて、ここまで来られたことに改めて感謝。 そして、いま、その皆さんとの約束が果たせたことにホッとしています。
We finally made it!
The Browsing ant Lepisiota frauenfeldi, whose establishment was confirmed along a national highway in Naha City in 2020.
After six years, on March 12, 2026, we have finally reached the declaration of eradication.
Having been involved in controlling this invasive ant since my OIST's days, I am now an independent researcher as the invasive species consultant after six years.
A member of the OIST, the Ministry of the Environment, and the Ryukyu Nature Positive— each time I appear in the news, I speak under a different affiliation, which feels like a career chronicle to me (^_^;)
I remember when this ant was first discovered, I asked for cooperation by saying, “Let's eradicate it someday and hold a joint press conference!”
I am deeply grateful for the support and cooperation of many collaborators.
And now, I feel relieved that I have fulfilled that promise to everyone.
If you are interested in more technical details about this control project, please check it out our scientific paper in which we describe more detailed data and their analyses!
Yoshimura M, Suwabe M, Tsuji K, Baba Y, Kakazu H, Miyagi T, Ogasawara M, Uematsu J, Economo EP, Ono K (2025) Maximum effect with minimum impact: A new selective control strategy for the Browsing ant Lepisiota frauenfeldi (Formicidae: Formicinae) minimize the impact on non-target species. PLOS ONE 20: e0337230. doi:10.1371/journal.pone.0337230.
Abstract
Early-stage control of invasive ants provides an opportunity to suppress establishment while conserving existing biodiversity. We developed and tested a selective control strategy targeting the Browsing ant Lepisiota frauenfeldi, an emerging omnivorous, polygynous, and polydomous invader, during its initial establishment in an urban area of Okinawa Island, Japan. Because the local ant community was still present when the invasion was detected, the trial aimed at reducing the competitive advantage of the target species while preserving biotic resistance from resident species. We hypothesized that weakening L. frauenfeldi through selective chemical treatment would allow existing species to occupy its vacant niches, thereby accelerating eradication. Species-specific baits were formulated using a growth regulator with protein- and carbohydrate-based substrates. Baits were placed near nest entrances identified through monthly surveys over an area of approximately 1.6 hectares. Ant community dynamics were monitored for 44 months using hand-collection and sticky-trap surveys. The invasive ant showed a strong negative response to treatment, with an estimated 92% reduction in occurrence probability, ultimately disappearing from the treated area. Several non-target ant species increased in frequency, consistent with expectation of the niche reoccupation, while most other species remained stable, indicating minimal impact on the broader community. Compared to conventional methods, this approach used drastically less chemical while achieving high efficacy. Implementation through cross-organizational collaboration enabled parallel treatment in adjacent restricted areas and contributed to the program’s success. These results highlight the practical and ecological value of nest-targeted, community-collaborative selective baiting as a strategy for managing omnivorous invasive ants during early establishment.
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