The Protozoacidal Effect of Tripropylisocyanurate (TPIC) on Symbiotic Protozoa in Japanese Subterranean Termites

抄録

To determine the protozoacidal effect of tripropylisocyanurate (TPIC) on symbiotic protozoa in two Japanese subterranean termites, Coptotermes formosanus and Reticulitermes speratus (RHINOTERMITIDAE), we examined the movement of the protozoa by microscope. After exposing the termites to TPIC (40 mg/filter paper), the protozoa, Pseudotrichonympha grassi in C. formosanus and Trichonympha agilis in R. speratus, significantly decreased their movement (p<0.05) after 2 and 8 hr, respectively. These protozoa are considered to play a crucial role in cellulose digestion in the termites. TPIC was therefore considered to damage the cellulose metabolism of the termites by affecting their symbiotic protozoa. The termite C. formosanus did not become moribund or die within 24 hr after exposure to TPIC (40 mg/filter paper), so the effect of TPIC thus emerged in the symbiotic protozoa much earlier than in the termites themselves. R. speratus, however, became moribund within 2 hours after TPIC (40 mg/filter paper) treatment, and it was concluded that TPIC first exerted its effect on R. speratus themselves before affecting the symbiotic protozoa.