Effects of an invasive ant on land snails in the Ogasawara Islands

Shota Uchida, Hideaki Mori, Tsubasa Kojima, Kayo Hayama, Yuko Sakairi, Satoshi Chiba

Research output: Contribution to journalArticlepeer-review

11 Citations (Scopus)


We investigated how Pheidole megacephala has affected endemic achatinellid snails because these snails are excellent indicators of the impact of ants and they have high conservation value in Ogasawara. In 2015 we surveyed the Minamizaki area of Hahajima Island of Ogasawara, designated a core zone of the World Heritage Site, for P. megacephala. In Minamizaki, we determined the distribution and density of achatinellid snails in 2015 and compared these data with their distribution and density in 2005. Land cover in the survey area was entirely forest. We also tested whether P. megacephala preyed on achatinellid snails in the laboratory. P. megacephala was present in the forested areas of Minamizaki. Achatinellid snails were absent in 19 of 39 sites where P. megacephala was present, whereas in other areas densities of the snails ranged from 2 to 228 individuals/site. In the laboratory, P. megacephala carried 6 of 7 achatinellid snails and a broken shell was found. Snail distribution and density comparisons and results of the feeding experiments suggest that the presence of P. megacephala has contributed to the decline of achatinellid snails in forests in the survey area. Yet, P. megacephala is not on the official list of invasive non-native species. Stakeholders using the list of invasive species to develop conservation programs should recognize that invasiveness of non-native species differs depending on the ecosystem and that official lists may not be complete.

Original languageEnglish
Pages (from-to)1330-1337
Number of pages8
JournalConservation Biology
Issue number6
Publication statusPublished - 2016 Dec 1


  • achatinellidae
  • achatinellidae
  • dispersión pasiva
  • especie introducida
  • Hahajima Island
  • introduced species
  • Isla Hahajima
  • isla oceánica
  • oceanic island
  • passive dispersal
  • Sitio UNESCO de Patrimonio Mundial
  • UNESCO World Heritage Site


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