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item Park, Yong
item Raina, Ashok

Submitted to: Journal of Insect Physiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/1/2005
Publication Date: 2/2/2005
Citation: Park, Y.I., Raina, A.K. 2005. Regulation of juvenile hormone titers by soldiers in the formosan subterranean termite, coptotermes formosanus. Journal of Insect Physiology 51: 379-384.

Interpretive Summary: Juvenile hormone III plays a key role in the formation of soldier caste in Formosan subterranean termite. There is little information available on how the specific hormone is regulated during development of the FST. We reported for the first time that JH III is very important growth hormone in the FST. It is important to understand the mechanism of soldier formation for developing novel methods to control the termite colony. There is a correlation between the hormonal titer and soldier proportion in the colony. When experimental colonies had less than 25% soldier, they produced more soldiers. However, the colonies with over 25% soldier not only did not produce new soldiers but also showed suppression of the hormonal titers under approximately 20 pg/mg. The information will be very useful for termite researchers to understand hormonal control of soldier formation and to be able to manipulate it for termite management.

Technical Abstract: In field collections of the Formosan subterranean termite Coptotermes formosanus, soldiers averaged less than 10%. The proportion of soldiers increased to about 25% or higher in the laboratory, as did the juvenile hormone III (JH III) titers for both workers and soldiers. In laboratory experiments with a proportion of soldiers 25% or higher, very few new pre-soldiers were formed and the JH titer in existing soldiers remained constant. On the contrary, workers from groups containing less than 25% soldiers formed more pre-soldiers. In such cases, both workers and soldiers showed higher JH titers. Newly formed soldiers also had higher JH titers than older soldiers. It is speculated that populations containing higher soldier proportions inhibit further soldier differentiation, eventually holding the JH titers under the threshold or suppressing the activity of corpora allata resulting in lower JH titers in workers.