Rafting on floating fruit is effective for oceanic dispersal of flightless weevils

Hui Ying Yeh, Hui Yun Tseng, Chung Ping Lin, Chen Pan Liao, Jung Ya Hsu, Wen San Huang*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

20 Citations (Scopus)


Terrestrial species, especially non-vagile ones (those unable to fly or swim), cannot cross oceans without exploiting other animals or floating objects. However, the colonisation history of flightless Pachyrhynchus weevils, inferred from genetic data, reveals their ability to travel long distances to colonise remote islands. Here, we used captive-bred Pachyrhynchus jitanasaius to analyse (i) the physiological tolerance of weevils (egg, larva and adult stages) to different levels of salinity; (ii) the survival rate of larvae in a simulated ocean environment in the laboratory; and (iii) the survival rate of larvae in a field experiment in the ocean using fruit of the fish poison tree floating on the Kuroshio current in the Pacific Ocean. We found that the survival rate of larvae in seawater was lower than in fresh water, although if the larvae survived 7 days of immersion in seawater, some emerged as adults in the subsequent rearing process. No adults survived for more than 2 days, regardless of salinity level. After floating separately for 6 days in salt water in the laboratory and in the Kuroshio current, two of 18 larvae survived in the fruit. This study provides the first empirical evidence that P. jitanasaius larvae can survive ‘rafting’ on ocean currents and that the eggs and larvae of these weevils have the highest probability of crossing the oceanic barrier. This ability may facilitate over-the-sea dispersal of these flightless insects and further shape their distribution and speciation pattern in the Western Pacific islands.

Original languageEnglish
Article numberjeb190488
JournalJournal of Experimental Biology
Issue number24
Publication statusPublished - 2018 Dec


  • Barringtonia asiatica
  • Fish poison tree
  • Kuroshio current
  • Oceanic islands
  • Pachyrhynchus jitanasaius
  • Salinity tolerance
  • Taiwan

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics
  • Physiology
  • Aquatic Science
  • Animal Science and Zoology
  • Molecular Biology
  • Insect Science


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