Isoptera
Taxonomic placing: Insecta, Hemimetabola, Blattodea. (The Isoptera were formerly considered a separate order, but recent evidence indicates an intimate relationship with the cockroaches).
Common name: Termites, white ants.
Geographical distribution: Subtropical and tropical regions; about 3,000 species are known.
Morphology: The termites are polymorphic, including large, brownish, individuals of several castes, especially workers and soldiers. The workers and soldiers have pale bodies, biting mouthparts and are blind, differing from each other by the massive heads and mouth parts of the soldiers. Wings, when present, bear elaborate venation.
Life history: The termites live in colonies of several thousand individuals, within nests or structures called termitaria. A colony consists of a “queen”, a “king” and very large numbers of workers and soldiers (for defense). The colony is established by the king and by the queen, which initially lays several hundred eggs. The emerging larvae molt to become workers, soldiers or reproductive termites, their fate being determined by pheromones produced by the king and/or by the queen. As the colony grows and matures, which may take several years, more and more eggs are produced. Should the queen die, some of the secondary reproductives begin to lay eggs. Later some of the molting larvae develop wings and eyes, becoming primary reproductives. Under suitable heat, light and moisture conditions they leave the nest (“swarm”) in pairs and fly, usually only for a short distance, to establish new colonies, concurrently shedding their wings. Workers and soldiers usually live about 1-2 years, whereas queens may live for 25 to 50 years, depending on environmental conditions and the species. Termites eat materials that contain cellulose, such as wood, plants, carpets, cardboard, sheetrock paper and fabrics, the cellulose being broken down to sugars by protozoa and bacteria that live in the termite digestive tracts. Termites also feed on insulation material and animal feces, and some feed on particulate or dissolved plant matter within mineral soil, thus considered to be soil-feeders. Some termites maintain “fungus gardens”, in which fungi are grown and used to supplement the termite diet with proteins and vitamins.
Economic importance: The main economic importance of termites is due to their burrowing into timber and sometimes destroying wooden buildings; several species are destructive invaders. They have positive and negative effects on agricultural soils; positive by increasing porosity, negative by cementing soil particles and eliminating plants that grow near their nests. A few species are agricultural pests in the Middle East, including Psammotermes hypostoma and Reticulitermes lucifugus Rossi.
Termites are active in soil formation, as their activities improve the structure of various soils, including egraded and crusted soils.
Management
Cultural control: Transported woods or wood-containing merchandise should be heated to above 50ºC in order to kill any termites nesting therein.
Chemical control: Woods or wood-containing merchandise can be fumigated during transportations. Various chemicals, like arsenate or creosote oil may protect houses, and pesticides, like pyrethroids and imidacloprid, are effective against agricultural pests.
Biological control: Termites have several natural enemies, especially ants and some entomopatogenic fungi. Although these enemies may reduce the size of colonies, they do not actually control termites.
References
Bignell, D.E., Roisin, Y. and Lo, N. 2011. _ Biology of Termites: a Modern Synthesis_. 2011. Springer, Dordrecht, pp. 576.
Breznak, J.A. 1982. Intestinal microbiota of termites and other xylophagous insects. Annual Review of Microbiology 36: 323-343.
Evans, T.A., Forschler, B.T. and Grace, J.K. 2013. Biology of Invasive termites: A worldwide review. Annual Review of Entomology 58: 455-474.
Harris, W.V. 1961. Termites, their Recognition and Control. Longmans, London.
Lee, K.E. and Wood, T.G. 1971. Termites and Soils. Academic Press, London, pp. 252.
Mando, A. and Miedema, R. 1997. Termites inducted changes in soil structure after mulching degraded (crusted) soil in the Sahel. Applied Soil Ecology 6: 241–249.
Mathew, T.T.G., Reis, R., DeSouza, O. and Ribeiro, S.P. 2005. Predation and interference competition between ants (Hymenoptera: Formicidae) and arboreal termites (Isoptera: Termitidae). Sociobiology 46: 409–419.
Wielemaker, W.G. 1984. _Soil Formation by Termites : a Study in the Kisii Area, Kenya. Wageningen,
Websites http://termites.myspecies.info/