Research

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.

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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).

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Figure 1. Range of Easter Subterranean Termite

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Movement Patterns in Statesville, NC

Animals move for a variety of reasons. Some of these reasons include finding food, finding shelter, and avoiding predators and/or competitors. We are interested in not only what types of animals can be found in and around Statesville, but also when these animals move. We are really interested in exploring patterns of animal movement in Statesville compared with more rural areas of the county.

This past semester (Fall 2015), student research teams placed motion-activated trail cameras throughout the city to gather preliminary data. The figures below show animal activity patterns in greenway spaces throughout the city. Around 2000 pictures were analyzed for these figures.

Figure 1 shows the daily activity patterns of six animals. Some of these activity times were expected. For example, we expected to see high raccoon activity during the overnight hours and high grey squirrel activity during the daytime hours. We did detect several coyotes during the day, but they tended to be more active in the dark. This may be due to the fact that the cover of darkness provides better hunting opportunities and also allows them to avoid humans in the greenway areas. Even though opossums, red foxes, and grey foxes were not as abundant (on camera anyway), we did “catch” several.

Figure 1

Figure 1

If we delete raccoon and opossum activity (Figure 2), we can look at times of movement between three predators and one potential prey (squirrel). Even though both the sample size (2000 pictures) and the length of time (Aug.-Dec., 2015) are both too small to understand completely, figure 2 allows us to ask (and try to answer) some questions. For example, it looks as though squirrels do a really good job at avoiding times when coyotes are active. This makes sense. If you are a squirrel you would do well to avoid a major predator. It looks like red foxes and grey foxes are avoiding each other. Maybe this is because they are competitors. Among the competitors, coyotes were detected more often. Clearly, they are the dominant predator in this particular ecosystem.

Figure 2

Figure 2

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