Team Building: Symbiosis between Termites and Microbes

Microorganisms subsist in the guts of some insects and help with the breakdown of cellulose and lignin and with nitrogen fixation. These particular insects and microorganisms developed a need for each other somewhere along evolutionary lineages, and now they actually benefit from each other in symbiotic relationships. Termites are one example of insects with protists, fungi, and bacteria living in their hindgut. Because termites diverged from cockroaches about 250 million years ago, exploring the similarities and differences of these two insects helps shed light on the evolution of microbial communities in their hindguts and the state of symbiosis in which they exist.

First, it is necessary to understand the digestion of these insects. Termites and cockroaches contribute to the degradation of wood because they have the ability to digest cellulose, a complex carbohydrate that makes up the cell walls of plants and is therefore the major component of wood. The diet of termites is usually high in cellulose because their food is mainly woody material. Cellulose is the most abundant form of carbon on Earth, excluding fossils (Martin, Jones, and Bernays 1991). Termites digest cellulose more efficiently than any other animal, and most animals are not able to digest this bountiful resource. Martin, Jones, and Bernays propose four ways that cellulose is digested in termites.



Termites in Anoxia?

The ability to survive changing environmental conditions has enabled certain insects to exist for millions of years. Termites, for example, have inhabited Earth for around 200 million years, and some species have the ability to survive periods of anoxia (Henderson 2001). Termites cost the United States close to 2 billion dollars annually (Kowalsick 2004). The reason for this is because landscape mulches are a source of cellulose, which attracts termites and may lead to house damage (Duryea et al 1999). In areas that flood for days or weeks at a time, termites can still pose problems to wooden structures. Therefore, it is beneficial to understand the physiology of termites and to explore how anoxic conditions affect the consumption rate of termites.

The Eastern subterranean termite, Reticulitermes flavipes, is native to the United States. It is one of the most common and widespread species of termites in the eastern region of North America and ranges from Toronto, Ontario to the gulf coast and eastward from the Great Lakes to the Atlantic coast (Krishna 1970). Along with the southern subterranean termite, R. virginicus, R. flavipes has the ability to forage for food 75 meters from the colony. Ninety-five percent of termite damage to wood comes from these two species (Duryea et al 1999).

Figure 1. Range of Easter Subterranean Termite