Estimating Population Size and Forager Movement in a Tropical Subterranean Termite (Isoptera: Rhinotermitidae)

Colony population size of Coptotermes acinaciformis (Froggatt), a species of mound-building, wood-eating, subterranean termite from tropical Australia, was estimated using a mark–recapture protocol and by direct counts of individuals collected from mounds. The mark–recapture estimates varied widely within and between colonies (0.4–19.1 million), depending on definitions of recaptures (intensity of color), and could be 10 times larger than the direct counts (1.2–1.6 million). Assumptions of the mark–recapture protocol were shown to be violated in field and laboratory tests. Nile blue A, a fatstain marker, did not persist and was transferred by cannibalism. Marked individuals did not mix uniformly with unmarked individuals; instead, foragers displayed feeding-site fidelity. The likelihood of recapture differed between castes and instars, there was a higher recapture rate of large workers and soldiers relative to small workers. These violations would increase population estimates from mark–recapture protocols. These results agree with those found for temperate species, suggesting that the difficulties with mark–recapture protocols are not limited to 1 habitat type or species, and that mark–recapture protocols do not estimate population size accurately.