Microbes & Management

Termites create a significant ecological impact in their habitat (Bourguignon et al. 2015). Besides feeding on dead wood and logs, several species of termites feed on wood from man-made structures, resulting in significant economic damage. Around the world, the economic damage of pest termites exceeds $30 billion per year (Rust and Su 2012). In response to the impact termites have on human habitats, researchers have spent decades learning as much about termite behavior and physiology as possible in order to develop potential control solutions. Recent research suggests the potential to mitigate insect damage by exploiting the basic termite biology (Scharf 2015).

A unique characteristic that distinguishes termites from other animals is their ability to digest lignocellulose — the tough material present in the cell walls of wood. Only worker termites feed on lignocellulosic materials in a termite colony, whereas soldiers defend the colony from foreign invaders and reproductives maintain the population (Roisin 2000, Lainé & Wright 2003).

The guts of termites harbor numerous symbionts — tiny bacteria and other microbes living in a consortium — to help them digest these lignocellulosic materials (Ohkuma 2008, Brune, Scharf & Tartar 2008, Ohkuma 2010). Termites, along with their gut symbionts, produce cellulase enzymes that break down cellulose and increase the digestive ability of the termite. The protist symbionts in termites are reported to contribute to cellulose degradation (Inoue et al. 1997, Inoue et al. 2000). Bacterial symbionts contribute to nitrogen fixation and some bacteria also protect the host against fungal pathogens (Doolittle et al. 2008, Peterson and Scharf 2016). Researchers are constantly examining the relationship between termites and their gut microbes to identify other potential interactions and connections.

In addition to digestion, numerous gut symbionts protect termites from pathogens and other infections (Chouvenc et al. 2013, Peterson and Scharf 2016). Disruption of these microbial communities may impact termite physiology, fitness and survivorship (Rosengaus et al. 2014, Peterson et al. 2015, Sen et al. 2015). These gut symbionts — both bacteria and protists — are shown to be disrupted by antibiotic treatments. Recent research has also shown that the digestive capacity of termites is compromised with antibiotic treatments (Peterson et al. 2015).

WORK IN PROGRESS. While the direct field use of antibiotics and other antimicrobials is not practical from a pest control standpoint, the investigation of these agents as potential synergists is well underway. These scientific insights allow for research on formulations that may include antimicrobial chemicals in addition to an insecticide, or even the development of a novel antimicrobial product specifically aimed at termite control.

For example, the Husseneder lab at Louisiana State University was able to engineer a termite gut bacterium which, when fed to termites, killed the protists that digest lignocellulose (Tikhe et al. 2017). The more we learn about the mutualistic properties between termites and their microbes, the more tools we will have available in our toolkit to limit termite damage to urban structures.

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The authors are both Ph.D. students at Purdue University, West Lafayette, Ind.