Estimation of mongoose-population utilizing exclusion of a necrophagous insect through competition on food resources

2019 Fiscal Year Final Research Report

• Project/Area Number: 17K07864
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Forest science
• Research Institution: Forest Research and Management Organization
• Principal Investigator: Ueda Akira 国立研究開発法人森林研究・整備機構, 森林総合研究所, 主任研究員 等 (90353599)
• Project Period (FY): 2017-04-01 – 2020-03-31
• Keywords: マングース / ネパールモンシデムシ / 絶滅 / 沖縄島 / 奄美大島 / 外来種 / 希少種保全 / 競争排除

Outline of Final Research Achievements

One of the necrophagous beetles, Nicrophorus nepalensis, uses a dead body of small vertebrates like mouse for its reproduction. Under the hypothesis that this beetle is locally extinct through feeding of dead bodies by the introduced mongoose, Herpestes auropunctatus, I collected the beetles to investigate their abundances and observed who used a dead body of mouse lied on the ground on Okinawa and Amamiohshima isles. As the results, no or few beetles were collected and almost dead bodies were fed by mongoose at areas where no control procedures of mongoose were done. On the contrary, a lot of beetles were collected and many dead bodies were used for reproduction of the beetle at the controlled areas. These cleared that the beetle suffers competitive exclusion by mongoose. Next, I tried to develop a model estimating mongoose-population from the beetle catches but failed to get good models.

Free Research Field

森林昆虫学

Academic Significance and Societal Importance of the Research Achievements

生物の絶滅要因として、環境の変化、捕食・採集圧、疫病、競争があげられる。そのうち競争による絶滅、すなわち競争排除の例は、近縁種や近縁分類群間で知られているが、哺乳類と昆虫間については未だ報告がない。本研究で、マングースによる小型脊椎動物死骸の摂食がネパールモンシデムシの繁殖資源を奪い、地域的な絶滅を生じさせているという競争排除が証明された。これは、食物資源をめぐる哺乳類と昆虫の競争で一方が絶滅するという生態学上非常に重要な発見となり、分類群が大きく異なる生物間でも競争排除が生じる事例として生態学の発展に大きく貢献するものとなった。