Blogging about animal behaviour (2010)

LSM1303 Animal Behaviour student posts

Nature’s Very Own Suicide Bombers

Filed under: Uncategorized — u0807641 at 9:41 am on Friday, April 9, 2010  Tagged , , , ,

No,  they are not terrorists.

Some insects in the animal kingdom have been known to self-destruct, as a form of altruism to save their colonies or brethren, when harassed or pursued by a predator.  Below are some examples of such self-exploding insects.

Camponotus saundersi

Taken from Sanpokai, from flickr

This species of ant, sometimes known as Exploding Ants or Kamikaze Ants, is found in South-east Asia, more commonly in Malaysia.  The ants contain the toxic substance in their heads and in 2 large glands on the sides of their bodies, called mandibular glands, which are filled with poison.  Under threat, they will explode their head to spew the poison or rupture their bodies by squeezing their abdomen.  This causes the glands to break and spray the sticky poison in all directions to engulf the predators, immobilising them.

This is a self-defensive mechanism called autothysis, when the organism ruptures an organ that explodes its body and kills itself in the process (Maschwitz and Maschwitz, 1974).  Another insect that uses this method is the Globitermes sulphureus.

Globitermes sulphureus

Taken from: http://www.termiteweb.com/termite-pictures-globitermes-sulphureus/

This species of termite is also found in South-east Asia, mostly in Vietnam and Malaysia.  The picture above shows a soldier termite with rather obvious mandibles or pincer-like hooks.  Under threat or when faced by a predator, the soldier termites first captures the predator by its mandibles.  It then squeezes its abdomen and this ruptures the glands that contain a stick yellow substance that hardens after exposure to the air.  The toxic substance, when explodes out of the termite’s body, covers not just the victim but the termite as well. And this is how the termites die together with their victims.  The substance also contains a pheromone that alerts other soldier termites to the danger.  A pretty nifty defensive mechanism!

Acyrthosiphon pisum

Taken from Aphidman on flickr

This is a pea aphid.  The pea aphid is an agricultural pest and natural predators like lady bugs are often introduced to control its population.  According to Thomas Joiner in an interview with Discovery News, these insects will explode themselves,and in the process saving their brethren by scaring off the predator.  The explosion may even kill the predator.  The pea aphid has also been known to explode after being consumed by its predator.  However, not many details are known about the actual physical mechanism that causes the explosion.  But this creature is no stranger to suicide.  Pea aphids are also parasitic hosts for wasps.  Wasps lay eggs aphids and and the young wasps will feed on its host before killing it when it emerges.  This parasitic behaviour poses a danger for a population of pea aphids, and thus in an act of self-sacrifice, the infected aphid will throw itself to the ground to be consumed by its predators (Joiner & Van Orden, 2008).

So you see, suicide bombers and suicide, is not just a human thing.

References:

1. http://en.wikipedia.org/wiki/Autothysis

Camponotus saundersi

1. http://en.wikipedia.org/wiki/Camponotus_saundersi (accessed 8th April 2010)

2. http://www.wsu.edu/~delahoyd/myrmidons.html  (accessed 8th April 2010)

Globitermes sulphureus

1. http://en.wikipedia.org/wiki/Globitermes_sulphureus (accessed 8th April 2010)

2. C. Bordereau, A. Robert, V. Van Tuyen and A. Peppuy,1997.  Suicidal defensive behaviour by frontal gland dehiscence in Globitermes sulphureus Haviland soldiers (Isoptera) (Abstract).  Insectes Sociaux, 44: 289– 296.  URL: http://www.springerlink.com/content/m727aywa4mdf04ln/fulltext.pdf?page=1 (accessed 9th April 2010)

Acyrthosiphon Pisum

1. “Animal Suicide Sheds Light on Human Behavior” by Larry O’Hanlon.  Discovery News, 10th March 2010. URL: http://news.discovery.com/animals/animal-suicide-behavior.html (accessed 8th April 2010)

2. http://ipm.ncsu.edu/AG295/html/pea_aphid.htm (accessed 8th April 2010)

3. Joiner, Jr., Thomas E. & Van Orden, Kimberly A., 2008. The Interpersonal–Psychological Theory of Suicidal Behavior Indicates Specific and Crucial Psychotherapeutic Targets. International Journal of Cognitive Therapy, 1(1): 84.  URL: http://www.atypon-link.com/GPI/doi/pdf/10.1521/ijct.2008.1.1.80 (accessed 8th April 2010)



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