Foraging choice and replacement reproductives facilitate invasiveness in drywood termites

All highly cryptic drywood termites derive their food and water from a single piece of wood. Despite the fact that most species share the same life cycles, only a few have become invasive tramp species. Variation in production of replacement reproductives and food size choice were determined for nine species of the important drywood genus Cryptotermes in a test with two different sized wooden blocks. Four native, non-pest species produced one or two reproductives, gnawed short tunnels and chose large blocks; four tramp pest species produced three or four reproductives, gnawed long tunnels and two species chose small blocks whereas the other two species chose both blocks; the ninth species, a native pest, was similar to tramp species. Longer tunnels and more replacement reproductives corresponded with pest status, acceptance of small blocks with tramp status. Although counter-intuitive, the foraging acceptance or preference for small blocks of wood corresponds with higher propagule pressure and an increased chance of (unwitting) human assisted transport, and therefore may be an important factor in determining tramp status of drywood termite species.