Termite Salinity Tolerance And Potential For Transoceanic Dispersal Through Rafting

1. 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. 2. Our results revealed that the survival rates ofIncisitermes inamurai(Oshima),Cryptotermes domesticus(Haviland),Prorhinotermes flavus(Bugnion and Popoff),P. simplex(Hagen), andHeterotermessp. are not affected by treatment with 3.5% saline water, strongly supported that oceanic rafting may be a mechanism underlying the insects' transoceanic distribution. 3. By contrast,Hodotermopsis sjostedtiHolmgren,Glyptotermes satsumensis(Matsumura),Coptotermes formosanusShiraki,Co.gestroi(Wasmann),Reticulitermes virginicus(Banks),R. leptomandibularisHsia and Fan, andR. kanmonensisTakematsu 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. 4. Phylogenetic positions and habitats of salinity-tolerant termites implied that the acquisition of salinity tolerance may relate to both phylogeny and coastal living.