More commonly encountered in Hong Kong are subterranean termites. They are so named, as their workings are usually associated with soil. Subterranean termites make passage ways through the soil to reach wood buried in it or in contact with it. Above ground contact with food sources is made either through connecting wood or through earthen tunnels known as mud or shelter tubes. The optimum temperatures for termite existence are between 24ºC to 35ºC. However, they can survive in temperatures from -3ºC to 37ºC. Humidity levels vary according to the environment. Within the nest environment, the humidity level is nearly 100%. The Formosan termite has proven to be the exception in that it does not need to maintain soil contact but can exist completely separated from the ground. This ability to exist in such a way means that it is highly adaptable to many conditions and environments. Formosan termites have been found to exist on the roofs of high rise buildings and even in ocean going vessels.
Termites are a group of detritophagous eusocial insects which consume a wide variety of decaying plant material, generally in the form of wood, leaf litter, and soil humus. They are distinguished by their moniliform antennae and the soft-bodied and typically unpigmented worker caste for which they have been commonly termed "white ants"; however, they are not ants to which they are distantly related. About 2,972 extant species are currently described, 2,105 of which are members of the family Termitidae.
|Formosan subterranean termite (Coptotermes formosanus)|
Soldiers (red-coloured heads)
Workers (pale-coloured heads)
Termites comprise the infraorder Isoptera, or alternatively the epifamily Termitoidae, within the order Blattodea (along with cockroaches). Termites were once classified in a separate order from cockroaches, but recent phylogenetic studies indicate that they evolved from cockroaches, as they are deeply nested within the group, and the sister group to wood eating cockroaches of the genus Cryptocercus. Previous estimates suggested the divergence took place during the Jurassic or Triassic. More recent estimates suggest that they have an origin during the Late Jurassic, with the first fossil records in the Early Cretaceous.
Similarly to ants and some bees and wasps from the separate order Hymenoptera, most termites have an analogous "worker" and "soldier" caste system consisting of mostly sterile individuals which are morphologically and behaviorally distinct. Unlike ants, most colonies begin from reproductively mature individuals called a "king" and "queen" which form a lifelong monogamous pair. Also unlike ants, which undergo a complete metamorphosis, termites undergo an incomplete metamorphosis that proceeds through egg, nymph, and adult stages. Termite colonies are commonly described as superorganisms due to the collective behaviors of the individuals which form a self-governing entity: the colony itself. Their colonies range in size from a few hundred individuals to enormous societies with several million individuals. Most species are rarely seen, having a cryptic life-history where they remain hidden within the galleries and tunnels of their nests for most of their lives.
Termites' success as a group has led to them colonizing almost every global landmass, with the highest diversity occurring in the tropics where they are estimated to constitute 10% of the biomass, particularly in Africa which has the richest diversity with more than 1000 described species. They are important decomposers of decaying plant matter in the subtropical and tropical regions of the world, and their recycling of wood and plant matter is of considerable ecological importance. Many species are ecosystem engineers capable of altering soil characteristics such as hydrology, decomposition, nutrient cycling, vegetative growth, and consequently surrounding biodiversity through the large mounds constructed by certain species.
Termites have several impacts on humans. They are a delicacy in the diet of some human cultures such as the Makiritare in the Alto Orinoco province of Venezuela, where they are commonly used as a spice. They are also used in traditional medicinal treatments of various diseases and ailments, such as influenza, asthma, bronchitis, etc. Termites are most famous for being structural pests, however, the vast majority of termite species are innocuous, with the regional numbers of economically significant species being: North America, 9; Australia, 16; Indian subcontinent, 26; tropical Africa, 24; Central America and the West Indies, 17. Of known pest species, 28 of the most invasive and structurally damaging belong to the genus Coptotermes. The distribution of most known pest species is expected to increase over time as a consequence of climate change.