Termite salinity tolerance and potential for transoceanic dispersal through rafting

• Published in: Ecological entomology Vol. 46; no. 1; pp. 106 - 116
• Main Authors: Chiu, Chun‐I, Mullins, Aaron J., Kuan, Kuan‐Chih, Lin, Ming‐Der, Su, Nan‐Yao, Li, Hou‐Feng
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Publishing Ltd 01.02.2021; Wiley Subscription Services, Inc
• Subjects: Archotermopsidae; Blattodea; Coptotermes formosanus; Cryptotermes; Dehydration; Dispersal; Dispersion; Driftwood; entomology; Glyptotermes; Heterotermes; Hodotermopsis sjostedti; humans; Incisitermes; Insects; Invasive termites; Kalotermitidae; Land bridges; oceanic rafting; Phylogeny; Prorhinotermes; Rafting; Reticulitermes virginicus; Rhinotermitidae; Saline water; Salinity; Salinity effects; Salinity tolerance; salt tolerance; Survival; Termites; transoceanic distribution; transportation
• ISSN: 0307-6946; 1365-2311
• DOI: 10.1111/een.12946

Oceanic rafting through driftwood has been hypothesized to be a mechanism underlying the transoceanic distribution of termites (Order: Blattodea). To test this hypothesis, we examined the salinity tolerance of 12 termite species from eight genera and three families, namely Archotermopsidae, Kalotermitidae, and Rhinotermitidae. Our results revealed that the survival rates of Incisitermes inamurai (Oshima), Cryptotermes domesticus (Haviland), Prorhinotermes flavus (Bugnion and Popoff), P. simplex (Hagen), and Heterotermes sp. are not affected by treatment with 3.5% saline water, strongly supported that oceanic rafting may be a mechanism underlying the insects' transoceanic distribution. By contrast, Hodotermopsis sjostedti Holmgren, Glyptotermes satsumensis (Matsumura), Coptotermes formosanus Shiraki, Co. gestroi (Wasmann), Reticulitermes virginicus (Banks), R. leptomandibularis Hsia and Fan, and R. kanmonensis Takematsu treated with saline water showed dehydration symptoms, and their mortality rates increased significantly within 12 days after treatment. These results indicate that these species are less likely to be dispersed through oceanic driftwood and that their transoceanic dispersal is rather more likely to occur through human transportation or land bridges. Phylogenetic positions and habitats of salinity‐tolerant termites implied that the acquisition of salinity tolerance may relate to both phylogeny and coastal living. Many termite species are transoceanic distributed and proposed to disperse through rafting, and examining their salinity tolerance is crucial to test such hypothesis. This study proved that many Kalotermitidae termites and some primitive Rhinotermitidae termites are tolerant to saline water; they showed very low salinity‐induced mortality and no symptoms of dehydration. All salinity‐tolerant termites inhabit coastal areas, less likely to access freshwater.