A juvenile hormone analogue with potential for termite control: laboratory tests with Reticulitermes santonensis, Reticulitermes flaviceps and Coptotermes formosanus (Isopt., Rhinotermitidae)

Abstract

Laboratory experiments with three species of termites were conducted to study the efficacy of a carbamate derivative of 2‐(4‐hydroxybenzyl)‐1‐cyclohexanone (W‐328). The compound has been found to be highly active causing differentiation of termite workers into presoldiers, soldiers and/or soldier‐intercastes. Differentiation of excessive soldiers induced by juvenile hormone analogues (JHAs) may disrupt the social homeostasis and consequently cause death of the whole termite colony. W‐328 induced differentiation into soldiers in 41–100% of individuals when applied in range of 50–500 ppm to a feeding substrate of wood in force‐feeding and choice bioassays with groups of Reticulitermes santonensis Feytaud and R. flaviceps (Oshima). Efficacy of W‐328 was also confirmed in choice bioassays with isolated groups of workers and soldiers and with incipient colonies of Coptotermes formosanus Shiraki. A high proportion of JHA‐induced differentiation into soldier caste was accompanied by increased mortality. Termites accept a matrix treated with W‐328 quite well. Significant feeding deterrence of the compound was observed only at higher concentrations: 500 ppm in some tests with Reticulitermes spp. and 5000 ppm in colonies of C. formosanus. Adequate persistence of W‐328 in corrugated cardboard (a potential feeding substrate for baits) was confirmed by bioassay with R. santonensis and by chemical analysis. The residue levels of the compound, applied at 500 ppm concentration, after 27 days of conditioning remain high enough to result in significant soldier differentiation.