Effects of different substrates and activated charcoal on the survival of the subterranean termite Coptotermes curvignathus in laboratory experiments (Isoptera: Rhinotermitidae)

Four different substrates, namely river sand, garden topsoil, vermiculite and a mixture of plaster of Paris and activated charcoal powder, were evaluated for their suitability as substrates in laboratory experiments with Coptotermes curvignathus (Isoptera: Rhinotermitidae). Survival was highest on vermiculite, lower on sand and soil and poor on the mixture of plaster of Paris and charcoal. Estimated 50% survival times were approximately 24, 17, 15 and 11 days, respectively, on these substrates. The high survival rate on vermiculitewas associated with greater tunneling and feeding activity. Physical characteristics of vermiculite that are likely to have contributed to the higher survival of C. curvignathus on this substrate are discussed. Although survival was poor on the mixture of plaster of Paris and charcoal, the incorporation of activated charcoal powder into vermiculite increased survival in two out of three colonies and reduced instances of premature mortality, thereby reducing variation and slightly increasing the overall survival rate. Estimated 50% survival time on vermiculite with charcoal was approximately 31 days as compared to 28 days on vermiculite alone. The results suggest that where optimal survival of the termites is required in laboratory tests, the addition of activated charcoal to substrates may be beneficial.