米国の蝶の個体数が急激に減少 (U.S. Butterfly Populations Are Severely Declining)

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2025-03-06 ワシントン州立大学 (WSU)

米国の蝶の個体数が急激に減少 (U.S. Butterfly Populations Are Severely Declining)
The Oregon silverspot butterfly. (Photo by Cheryl Schultz, Washington State University)

ワシントン州立大学の研究者たちは、米国の蝶の個体数が過去20年間で22%減少したことを明らかにしました。この減少は、76,000件以上の調査と340種以上の蝶を対象とした包括的な研究に基づいています。主な原因として、生息地の喪失、農薬の使用、そして気候変動が挙げられています。特に、南西部の州(アリゾナ州、ニューメキシコ州、オクラホマ州、テキサス州)では、個体数の減少が顕著で、これらの地域では50%以上の減少が報告されています。さらに、フロリダホワイトやミッチェルズサテュルなどの種は、個体数が99%以上減少しており、絶滅の危機に瀕しています。このような蝶の減少は、食物連鎖や生態系全体に深刻な影響を及ぼす可能性があります。蝶は重要な送粉者であり、その減少は植物の多様性や農作物の生産性にも影響を与える可能性があります。研究者たちは、生息地の回復や気候変動への対策など、蝶の個体数減少を逆転させるための行動が必要であると強調しています。

<関連情報>

21世紀におけるアメリカ全土でのチョウの急激な減少 Rapid butterfly declines across the United States during the 21st century

Collin B. Edwards, Elise F. Zipkin, Erica H. Henry, Nick M. Haddad, […], and Cheryl B. Schultz
Science  Published:6 Mar 2025

Editor’s summary

Reports of declining insect populations have received widespread media attention, but evidence for declines has been variable across regions and taxonomic groups. Edwards et al. examined trends in the most surveyed taxon: butterflies (see the Perspective by Inouye). Combining data from 35 citizen science programs across the continental US, the authors found declines in overall butterfly abundance over the past 20 years across almost all major regions. Two-thirds of studied species showed declines of more than 10%. Many insects have the potential for rapid population growth and recovery, but habitat restoration, species-specific interventions, and reducing pesticide use are all likely needed to curb population declines. —Bianca Lopez

Abstract

Numerous declines have been documented across insect groups, and the potential consequences of insect losses are dire. Butterflies are the most surveyed insect taxa, yet analyses have been limited in geographic scale or rely on data from a single monitoring program. Using records of 12.6 million individual butterflies from >76,000 surveys across 35 monitoring programs, we characterized overall and species-specific butterfly abundance trends across the contiguous United States. Between 2000 and 2020, total butterfly abundance fell by 22% across the 554 recorded species. Species-level declines were widespread, with 13 times as many species declining as increasing. The prevalence of declines throughout all regions in the United States highlights an urgent need to protect butterflies from further losses.

1903自然環境保全
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