Asssesment of Initial Colony Founding by Swarming Reproductives of the Western Drywood Termite, Incisitermes minor

Abstract

Colony founding activities in drywood termite is difficult to assess, since the colony forage and nest inside the wood. Non-destructive observation using X-ray computed tomography was used to evaluate nest-gallery establishment and colony breeding of the incipient colonies. The infested timbers were marked by year of infestation and were left on its original position to allow termite colonies develop in natural environment. Selected timbers were subjected for X-ray scanning analysis in Kyushu National Museum, Japan, in which colony founding from 5 royal pairs in the first year development was monitored. The CT data of the first six months colony founding indicated two different outcome in colony founding; two colonies distributed the energy to breed and slowed down in foraging simultaneously and other three concentrated in foraging. The CT scan after one year showed that only one royal pair showed no breeding activity, while the other four had been observed to have 2 – 5 new colony members. Colony extraction also confirmed that colony size in the first and second year varied from 0 – 5 new colony members. The new colony members were mostly in larval instars, sometimes with the presence of one small soldier. Colony founding through nuptial flight is a risky process, as 59% of the observed chambers were failed colony founding, resulted from the dead of a royal pair or being abandoned (empty chamber).