Nate Lo

Origins of termites

Nasutitermes triodiae nest. Photo T. Abe	Termites are famous for their ability to destroy wooden structures. In Australia, 1 in 3 houses will eventually be affected by termites, and the annual cost of infestations is estimated at 780 million dollars. From a biological point of view, termites are important components of natural ecosystems, performing functions such as carbon recycling and soil aeration, and acting as a food source for various mammals. Termite nests are the largest non-human built structures in the world.
Macrotermes subhyalinus. Photo R. Leuthold	Along with bees, wasps and ants, termites are one of the main groups of social insects. These fascinating insects are characterized by a reproductive division of labour: the vast majority of colony members are usually sterile and perform work, while just a lucky few undertake all the reproduction. This phenomenon has traditionally been considered a kind of evolutionary conundrum. How could genes that cause sterility be passed on to offspring? The answer appears to be that such 'altruism' genes are switched off in some individuals (reproductives), and switched on in others (workers).
Cryptocercus punctulatus. Photo K. Maekawa	To aid understanding of how termites evolved, I initiated studies aimed at determining their closest living relatives. By sequencing and comparing various genes in termites, cockroaches and praying mantids, it was found that termites are most closely related to wood-feeding cockroaches of the genus Cryptocercus.
Mantis octospilota. Photo D. Rentz	Termites can thus be considered a type of derived cockroach. Cryptocercus is a sub-social cockroach: an adult male and female raise a single clutch of offspring over a period of several years. The ancestor of termites and cockroaches presumably had this characteristic. A key step in the evolution of termites would have been the production of second clutch of offspring, which would have been raised by the first group of offspring. This would have allowed the queen to focus on egg-laying, and so on.
Polyzosteria mitchelli. Photo D. Rentz

Publications relevant to this research: 6, 7, 11 15, 20