Termites. Termites. Termites.

By S.C. Lougheed
For Ontarions, the word “termite” conjures up a negative image of ravenous insects that cause immense and costly damage to human-made wooden structures because of their propensity to eat dead wood and indeed any material that is cellulose-based (Evans 2011). The beast that we know in Ontario is the eastern subterranean termite (Reticulitermes flavipes), a species native to the eastern USA that has been introduced multiple times into Ontario (Scaduto et al. 2012) – probably first in 1938 (Urquhart 1953).

Figure 1. A particularly impressive cathedral termite (Nasutitermes triodiae) mound estimated to be over 50 years old and over 4 metres tall (Queen’s University Biology alumnus Cam Hudson, provides some idea of scale ).
Figure 1. A particularly impressive cathedral termite (Nasutitermes triodiae) mound estimated to be over 50 years old and over 4 metres tall (Queen’s University Biology alumnus Cam Hudson, provides some idea of scale ).

In other parts of the world, like the savannahs of African savannahs, the pampas of Argentina, or tropical and subtropical Australia, some termite species present another face – that of exquisite natural engineers who create magnificent and sometimes immense structures of cellulose, mud and saliva (Figure 1). These termite mounds afford many benefits to the termite colony including protection from predators and buffering from sometimes extreme environments where they are found. In the Box below I present some basic information on evolutionary affinities and diversity.

Figure 2. A field of magnetic termite mounds in Litchfield National Park, Northern Territory, Australia.
Figure 2. A field of magnetic termite mounds in Litchfield National Park, Northern Territory, Australia.

One of my favourite examples of beautifully-adapted insect architecture is the mound of the magnetic termite, Amitermes meridionalis, found in Northern Australia. Magnetic termites build their wedge-shaped mounds on seasonal flood plains that are saturated during the wet season (precluding subterranean abodes) and baked in the intense tropical sun in the dry season – an extreme environment indeed! The photo in Figure 2 shows that the mounds are all oriented in the same direction – north-south. The unique shape and orientation mean that one side is shaded and cool as the sun rises and sets, but also that when the sun is at its zenith, only the very top of the wedge receives direct sunlight. Termite mounds can be incredibly important to other organisms. Hollows within them can provide shelter for animals like goannas (monitor lizards), quolls (small marsupials), and snakes. For some species termites form a significant part of their diet (e.g. bilbies – small arid-land omnivorous marsupial) and termite mounds thus a rich foraging ground. Finally termite mounds play a significant role in enriching and cycling of nutrients, with local effects persisting decades after a colony has disappeared.

References

  1. Evans, T.A. 2011. Invasive termites, pp. 519-562. In D.E. Bignell, Y. Roisin, & N. Lo Eds., Biology of Termites: A Modern Synthesis. Springer, Dordrecht, the Netherlands.
  2. Scaduto D.A., S.R. Garner, E.L. Leach & G.J. Thompson. 2012. Genetic evidence for multiple invasions of the eastern subterranean termite into Canada. Environ. Entomol. 41: 1680-168.
  3. Urquhart, F.A. 1953. The introduction of the termite into Ontario. Can. Entomol. 85: 292-293.

Box. There are over 3000 named species of termites (also called “white-ants”), although undoubtedly there remain many others to be discovered (Krishna et al. 2013). Much of this species richness is centred in the tropics and subtropics, where termites play a major role in ecosystems as detritivores. Originally placed within their own order (Isoptera), recent molecular evidence suggests that termites are most closely allied to cockroaches with suggestions that Isoptera be subsumed within the cockroach order Blattodea (Inward et al. 2007). Termites are eusocial insects where different castes perform different roles within the colony. This phenomenon of eusociality has arisen multiple times both in insects (e.g. Hymenoptera – bees and wasps), in crustaceans (alpheid snapping shrimp), and in mammals (naked mole rats, Heterocephalus glaber).

References

Inward, D., G. Beccaloni & P. Eggleton. 2007. Death of an order: A comprehensive molecular phylogenetic study confirms that termites are eusocial cockroaches. Biol. Lett. 3: 331-335.

Krishna, K, D.A. Grimaldi, V. Krishna & M.S. Engel. 2013. Treatise on the Isoptera of the world. Bull. Am. Mus. Nat. Hist.  377: 1–2704.

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