Isoptera Takuya Abew and Masahiko Higashiw, Kyoto University, Kyoto, Japan r 2001 Elsevier Inc All rights reserved This article is reproduced from the previous edition, pp 581–611, r 2001, Elsevier Inc Glossary Alate An imago still possessing its wings Caste A group of individuals in a colony that are both morphologically distinct and specialized in behavior Imago The adult insects; the final developmental stage when insects possess wings Larva An immature individual without an external sign of wing buds or soldier morphology Neotenic A secondary reproductive with juvenile morphological characters Neotenics derive from larvae, nymphs, pseudergates, or workers through at least one special moult Nymph An immature individual on the developmental pathway to the imago and which possesses external wing buds Presoldier A transitional morph that always precedes the soldiers; an unsclerotized individual whose head shows signs of soldier differentiation Primary reproductives Dealate reproductives that founded a new colony after nuptial flight Pseudergate (false worker) A temporarily nonreproductive individual serving the colony in nutrition, Introduction The Isoptera is a relatively small order of insects that consist of 31 orders, including about 2650 described species The order name Isoptera originates from the fact that the imago (adult) has wings of equal size (Isos in Greek meaning the same and ptera meaning wings) The insects of Isoptera are commonly called termites in English Due to their poor abdominal sclerotization and white appearance, they are often called ‘‘white ants’’ in many temperate regions However, they are not phylogenetically closely related to ants, but to cockroaches and mantises Termites are sometimes black, reddish brown, or yellow in body coloration in tropical regions Termites are widely distributed in tropical and sub-tropical regions, spreading from humid forests to savannas and even arid areas Their biomass approaches 10 g wet weight/m2 Only a few animal groups such as human beings, earthworms, herbivorous mammals in African savanna, and ants claim this order of biomass The basis of this extraordinary prosperity of termites lies in their feeding habits They consume cellulose, which is the most abundant organic matter on the earth The ecological basis of their prosperity is their symbiosis with microorganisms and their highly developed social organization w Deceased 408 construction, or brood care, which results from a late, reversible deviation from the pathways to the imago and is characterized by reduced wing buds compared to nymphs of the same stage Queens and kings Females and males that actively reproduce in a colony Secondary reproductives Reproductives that differentiated in an established colony, whatever their origin and morphology They may be supplementary reproductives if older reproductives are still present or replacement reproductives if not Soldier An individual with a strongly sclerotized head showing defensive adaptations, such as enlarged mandibles, a stopperlike shape, or a frontal gland able to produce a defensive secretion Worker An individual resulting from an early, irreversible deviation from the pathway to the imago, and performing helper tasks Workers are primarily characterized by the loss of the ability to proceed to the winged imago, but they need not be permanently sterile The symbiosis produces novel abilities that cannot be attained by either of the partners alone In particular, the symbiosis between higher organisms and microorganisms often creates capabilities for exploiting new food resources such as dead plant material containing large amounts of cellulose, which is a potential energy source but difficult for most animals including human beings to utilize On the other hand, sociality enhances the efficiency of resource exploitation Either of these or both together may cause a rapid growth and spatial expansion of the population, leading to diversification Animals in the tropical rain forests where the species diversity is the highest in the world are characterized by the dominance of social insects (termites, ants, social wasps, and social bees), and the dominance of symbiotic associations Termites possess both of those attributes Termites and ants occupy about one-third of total animal biomass in Amazonian tropical rain forests The symbiosis and sociality in termites, together with their super abundance, brings them to play a keystone role of ‘‘super decomposer’’ of dead plant material in tropical terrestrial ecosystems They consume and transform a large amount of nitrogen-poor dead plant material into nitrogen-rich termite body, which is in turn consumed by a great variety of animals ranging from ants and spiders to chimpanzees and human beings Thus they form the basis for a Encyclopedia of Biodiversity, Volume http://dx.doi.org/10.1016/B978-0-12-384719-5.00200-8