Isoptera Defense Strategies

Termite defense mechanisms are intertwined with their caste system since the caste system is a system that protects the essential functions of the colony. The termites have three different castes. The first caste is the reproductive. Reproductives usually include a king and queen with occasional supportive members that aid in egg laying. This caste is responsible for colonizing and producing offspring. Since the queen is laying all the eggs and ensuring the success of the colony, there are other termites that protect the queen from danger. This caste is called the soldier caste, and its members are characterized by large bodies (though the queen’s body is enormous since she lays so many eggs). These termites use chemicals or powerful jaws to protect the queen and guard the nest. Though, these termites cannot care for themselves, leaving that work to the worker termites. The final caste is the worker caste, which includes most of the termites in the colony. These termites perform all the work from carving new tunnels to cleaning the other termites.

Both termite soldiers and workers participate in the defense of the colony, but the soldiers have specialized body parts to enable them to better defend the colony.  Termites have evolved an amazing array of types of mandibles to assist in defense.  Slashing mandibles are the most common, but other species have developed mandibles that crush or pierce their enemies.  Additionally, some termite species have developed snapping mandibles.  The soldiers of these species are able to accelerate their mandibles to amazing velocities to strike whatever enemies are attacking their nest.

Termes panamaensis soldier

Termes panamaensis soldier

The quickest mandible strikes recorded to date are those of Termes panamaensis, a species native to Panama.  The mandibles of this termite can exceed 67m/s, taking just .025 milliseconds to complete the strike.  Muscle contraction alone cannot produce this kind of acceleration.  Rather, energy is stored through deformation of the mandibles.  At rest, the mandibles touch at the tip and separate towards the labrum.  As the termite prepares to strike, the point of contact move closer to the labrum as the mandibles deform, storing the energy from the muscle contractions.  Then, the mandibles suddenly cross over each other, releasing all of this energy at once.  The force of this blow if often enough to kill the insect the termite attacked, usually an invading ant or termite of a different species.  This is an amazingly effective defense strategy this species has evolved.

However, specialized mandibles are not the only defense that termites have developed, nor the most extreme. Some die for the greater good of the population as a whole. For instance, some termites use a defense tactic of defecating on enemies with “great precision,” while others have evolved another ability called dehiscence, where the termite bursts its body and spills its organs on threats.  Some termites, when they get old, develop chemical sacs that they can use to explode on enemies to protect their colonies. In a practice termed autothysis, which may have evolved from dehiscence, the termites destroys itself via an internal rupturing or explosion of an organ, and chemicals in glands mix with crystals to create a highly toxic and sticky substance that damages and incapacitates enemies.

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Neocapritermes taracua

Neocapritermes taracua is on type of termite that is known to use this technique when in danger. They grow a little sack of toxic blue liquid that they explode when facing a potential enemy that might harm their colony. The Neocapritermes taracua’s explosion is a form of autothysis. This implies that the explosion also causes the demise of Neocapritermes taracua. Unlike defensive autothysis in other insects, the Neocapritermes taracua’s sacrifice is unique because it employs a “two-component chemistry” method to ensure its target is thoroughly defeated. Neocapritermes taracua is a neo-tropical termite and commonly resides in decayed wood on which it feeds. It does not consist of many solider, so the workers also possess the exploding defense mechanism. With its explosive trait, Neocapritermes taracua is a deadly termite that has a unique composition and is a fascinating species to study.

Termites have developed a variety of techniques to defend their colonies, some taking advantage of principles of physics and chemistry and some involving self-sacrifice for the good of the colony.  The sophistication and diversity of these methods is truly incredible.

Links:

http://www.annualreviews.org/doi/pdf/10.1146/annurev.en.29.010184.001221

http://www.nature.com/news/termites-explode-to-defend-their-colonies-1.11074

http://www.sciencedirect.com/science/article/pii/S096098220801261X

http://www.sciencedirect.com/science/article/pii/S146780391400022X

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