Comparison of the Efficacy of Eleven Soil Termiticides on the Formosan Subterranean Termite (Coptotermes formosanus)

Using the tunneling test, the standard test method recommended by the JWPA ( JWPS-TS-S), the minimum effective concentrations of 11 chemicals, known as major soil termiticides in Japan, were determined. Addition of the emulsifying agent, Tween 80, to the low water solubility chemicals among the termiticides yielded a 2- to 8-fold increase in their termiticidal efficacies. In contrast, addition of Tween 80 to the high water solubility chemicals produced no such enhancement of their termiticidal efficacies. In the confined test, in the case of the repellent-type chemicals of the 11 chemicals, all the test termites (10 workers and 2 soldiers) became intoxicated or paralyzed and moribund within one hour of exposure to the minimum concentration fulfilling the criteria of the JWPA standard test method. In the case of non-repellent type chemicals, all the workers became moribund within 2 hours of exposure to the minimum concentrations fulfilling the criteria of the standard test method; in contrast, it took 4 – 24 hours before the soldier termites became moribund.