Frontal-pore formation during soldier differentiation induced by juvenile hormone III in the termite Reticulitermes speratus (Isoptera: Rhinotermitidae)

Termites show a highly controlled society. It is thought that the regulation of caste differentiation is fundamental to termite societies. To understand the proximate mechanisms of caste differentiation, this study focused on soldier differentiation induced by juvenile hormone (JH) III in the termite Reticulitermes speratus. To understand the differences between newly molted workers (before pigmentation) and presoldiers with various mandibular lengths induced by JH III, the frontal pore of each individual was observed by low-vacuum scanning electron microscopy. Frontal-pore formation was observed in newly molted individuals with elongated mandibles even in the individuals with relatively short worker-like mandibles. From this study, frontal-pore formation is suggested to be the indicator to identify the worker-presoldier molt induced by JH III. The present findings also showed that higher JH III concentrations are needed for mandibular elongation than for frontal-pore formation during presoldier differentiation. On the basis of these results, JH-regulated organ developments duringsoldier differentiation in R. speratus are discussed.