General Information about Termites (2)
Termite Life Cycle and Caste System

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The simplified model of a termite life cycle indicates the three castes, the reproductives, the soldiers and the workers. Due to the fact that termites are hemimetabolous insects, even the nymphs take part in the social life and have their specific tasks to fulfil. The so far poorly understood concept of caste determination does not seem to be definitive or too rigid. Once the caste of an individual is determined, development into other castes is still possible. Soldiers, also referred to as intercastes might turn into workers or even into reproductives, if there is a shortage of individuals of other castes. This process is controlled by pheromones. In the case of the queen, there is a specific ‘queen’ pheromone, preventing other individuals from turning into queens. Only if the queen is removed or dies, does the lack of the specific pheromone promote the development of a new queen.

Reproductives
possess compound eyes and are more or less brown due to their sclerotized cuticle. Developing reproductives have wing buds, wings or wing stumps. Reproductives can be further divided into:
  • Alates, the young winged reproductives of both sexes. From time to time about 100 to 1000 alates leave the colony for a mating and colonising flight. After mating a pair settles down at a suitable site like a rotting scar on a tree in order to establish a new colony.

  • De-alates, alates that cast their wings after the colonising flight and successively turn into queens and kings. Initially only a few eggs are laid and brought up by a female de-alate. As the number of individuals in the colony grows, the more workers are available to help the young queen to care for the brood. After three to five years the number of individuals is already so large, that the colony of a pest species can turn into the damaging stage.
  • Queen and king, which are the main reproductive individuals in a colony. Once there are many workers to help the queen, her only job is to produce a tremendous number of offspring. A large queen may lay more than 1000 eggs per day. The life span of a queen can be as much as 50 years.

  • Neotenics assist the queen in laying eggs, once her productivity decreases. When the queen has died or deteriorated, one of the neotenics takes her place. That is the reason why the removal of a queen from her colony does not necessarily mean the end of the colony
Workers are sterile, wingless and blind males and females. Their cuticle is unpigmented and not hardened, therefore the animals are confined to a dark and moist environment. Workers build the nest and galleries, they fetch food, care for the brood and feed reproductives and soldiers. The worker’s life span is one to two years.

Soldiers are, like workers sterile, wingless and blind males and females with an unpigmented, unsclerotized cuticle. Soldiers defend their colony from intruders by the use of powerful jaws and/or by ejecting a white sticky repellent from an opening on their head. Soldiers can’t feed themselves, they have to be fed by workers. Usually the number of soldiers is much smaller than the number of workers. Soldiers can be mandibulate or nasute, depending on the species. Therefore soldiers can be used for the identification of termite species. The life span of the soldiers is one to two years.

(drawings reproduced from Hadlington, P., 1992)


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Michael F. Schneider, 1999