When I was a master-course graduate student, I was working in a Bornean rain forest, called “Bukit-Soeharto Protection Forest”, in East Kalimantan, Indonesia. The forest belongs to University Murawarman, which is a local university in East Kalimantan. There, I was studying on the foraging behavior of an interesting termite species Hospitalitermes medioflavus.
Before entering the graduate course, I had wanted to stydy in tropical rain forests, because I imagined that such rain forests showed that the highest diversity of organisms all over the world. So, I determined to join a lab at Univ Tokyo, which was studying on the ecology of social insects in tropics.
At first, I wanted to work on relatively large insects with interesting morphologies, like horned beetles, praying mantids, or leaf insects. However, it was very hard to find such insects. Instead, social insects like ants and termites were everywhere on the forest floor. But I didn’t want to work on such tiny bugs…
The only social insect species that attracted me is a black termteis that performed the large foraging march. They feed on lichens on tree trunks or rocks, and carry lichen foods in the form of small balls, back to their nests.
Thus, I decided to work on this termite species, firstly on the division of labor among workers when foraging. Among foraging workers, I found three types of workers, i.e. major, medium, and minor workers. Major and medium workers are engaged in a task carrying foodballs, while medium and small ones in a task gathering foods.
The above photo shows the foraging castes, including three types of workers and “nasute” soldiers with a frontal projection, from which defensive substances are discharged to repell predators.
My subsequent works revealed that medium and major workers are female, and minor workers and soldiers are male. Female major and medium workers, and male minor workers and soldiers are in the different stage of postembryonic development respectively.
In conclusion, it was shown that the eraborate social behavior was accomplished by the caste systems, which were determined by the sexes and the developmental stages of individual insects. Thus, my interest moved towards the developmental control of caste differentiation…