Termites

Isoptera. Spanish: Comejenes, hormigas blancas, palomillas de San Juan, polillas de la madera (General). Portuguese: cupins (sing, cupim), formigas bran^as, formigas de asa, tucurus, aleluias do cupim (alates) (Brazil).

Termites are the analogues in tropical soils of earthworms in temperate regions. All Neotropical termites, except Kalotermiti-dae, live in the soil or maintain a close connection between nest and soil (pi. If). Their physical burrowing to construct nests and digestion of plant structural material (cellulose) add significantly to soil fertility and earn termites a place in nature as very beneficial insects, notwithstanding the few species that damage man's structures (Snyder 1924). Their role as soil animals has been studied more in other regions (Lee and Wood 1971) but is certainly similar in Latin America.

Recently, it has been realized that termites also have the potential to alter the environment in other ways, principally by releasing large amounts of methane, carbon dioxide, and hydrogen gases into the atmosphere as by-products of cellulose digestion. The greatest emissions come from natural tropical wet savanna and areas of human disturbance, such as cleared, burned, and cultivated lands, where abundant wood resources are available (Zimmerman et al. 1982).

Termites live in nests (termitaria) of their own construction. The form and location of these structures vary among the different kinds of termites. They may be wholly subterranean with mounds covering or linked to subsoil chambers by tunnels or arboreal masses off the ground but with runways communicating with the soil surface. Mounds may be large, rising 3 to 4 meters aboveground and forming conspicuous edifices in the landscape, particularly noticeable in open, flat country (Lacher et al. 1986). Such are the nests of

Cornitermes cumulans, common in pastures, cultivated land, and savannas in southern Brazil (Redford 1984). Arboreal nests may also be large, obvious, ovoid structures, but these are lodged on branches of trees and shrubs.

The materials used for construction depend on the termites' feeding habits and availability. They usually consist of clay soil, excreta, and plant fragments mixed with saliva.

The nest generally has an inner labyrinth of chambers, including special central rooms for the royal pair, where eggs are laid and the brood is raised (and in some cases, where food is stored and fungus cultivated). This is surrounded by a protective wall, itself sometimes perforated with galleries that lead to the exterior. There may also be long tunnels running to the surface, along the ground, or on the trunks and main limbs of trees. There is no clear correlation between nest architecture and termite systematics (Noirot 1977).

It is difficult to generalize about the biology of the fauna because so very little is known about only a few species (Matthews 1977, Araujo 1970). Amitermes constructs nests with a very tall portion aboveground, some with umbrellalike lateral projections that function as rain-shedding devices. Syntermes (fig. 5.i3a) is restricted to South America and is conspicuous because of the large size of individuals of most species (BL up to 17 mm or more) and the enormous volcano-shaped nests of some. Workers cut fragments of leaves and grass stalks and transport them to undergound galleries where they become stores for later consumption. Neocapritermes soldiers (fig. 5.13b) carry large, asymmetrical mandibles that may be snapped crosswise explosively, emitting an audible click and driving the sharp angulate tips into the skin of any animal holding it.

Nests of many species provide an inviting abode for an assemblage of other higher animals, including nesting birds.

Figure 5.13 TERMITES, (a) Common tropical termite (Syntermes dirus, Termitidae), reproductive male, (b) Crooked jaw termite (Neocapritermes braziliensis, Termitidae), head of worker, (c) Common tropical termite (Syntermes sp., Termitidae), physogastric queen from macropterous female, (d) Nasute termite (Nasutitermes costalis, Termitidae) worker, (e) Nasute termite soldier, (f) Nasute termite nest.

Figure 5.13 TERMITES, (a) Common tropical termite (Syntermes dirus, Termitidae), reproductive male, (b) Crooked jaw termite (Neocapritermes braziliensis, Termitidae), head of worker, (c) Common tropical termite (Syntermes sp., Termitidae), physogastric queen from macropterous female, (d) Nasute termite (Nasutitermes costalis, Termitidae) worker, (e) Nasute termite soldier, (f) Nasute termite nest.

Many reptiles, such as legless lizards, feed on termites and occupy termitaria almost continuously. In Amazonia, in the forest away from normal sunlit riverbanks, females of the crocodilian Paleosuchus tri-gonatus find ground nests a convenient incubator for their eggs (Magnusson et al. 1985). According to locals, the Amazonian tortoise (Geochelone) also employs nests in this manner (orig. obs.). Many mammals specialize on termites as food, particularly the so-called anteaters. They eat more termites than ants, tearing open the nests with their powerful front claws.

There are some true commensal termito-philes also among the insects and arthropods. These are other termites, silverfish, scale insects (Termitococcus, Margarodidae), and even tiger beetles that live in intimate association with termite colonies. Many beetles, particularly some rove beetles, are highly modified for life among termites (Kistner 1969). Abondoned nests of one kind of termite can be taken over by termites of a diff erent species.

As is true of termites in other parts of the world, there are those habitually found in man-made structures that can cause considerable damage when they feed on important wooden members. Some of these, such as Cryptotermes brevis (Wolcott 1957) and Coptotermes havilandi, are introduced from other places in the world, but some indigenous species are major pests as il well, for example, Incisitermes snyderi and Coptotermes niger.

Termites are social insects and exhibit complex group behavior similar to that of ants and social bees and wasps. They are fundamentally different, however, in having gradual metamorphosis and thus not having to provide for helpless larvae and pupae. Individuals comprising a colony are really members of a large family of sibling progeny started by a single paired winged reproductive male (fig. 5.13a) and female. The female queen is accompanied throughout her life by the attendant male and may live many years, growing in size to tremendous proportions (fig. 5.13c). The offspring consist of morphologically and functionally different castes that may be produced from newly hatched immatures, depending on the requirements of the colony. Control of this development depends on pheromones given off by members of the reproductive castes.

Sterile castes are the workers and soldiers, wingless individuals in which the growth of the reproductive organs is suppressed. The f ormer are the most numerous and generalized in form. They are responsible for all foraging activity and care for the eggs, larvae, and queen.

Soldiers have similar bodies but highly modified mouthparts and an enlarged, strongly sclerotized head. There are two well-defined types, those with large promi nent mandibles and the nasutes with a snoutlike prolongation on the front of the head and vestigial mandibles. Both actively defend the nest against attackers, by biting and pinching or by the emission of viscid, noxious secretions (Deligne et al. 1981; Prestwich 1983a, 19836). The head of the soldiers is so modified that they cannot feed themselves.

Depending on the species, the colony's primary food is dead wood and other vegetative parts of plants (usually dry), roots, humus, dung, and fungi, although the last are not cultured in Neotropical forms as in some in Africa. To a large extent, termites are dependent on unique, symbiotic flagellate protozoa and bacteria for digestion of cellulose and other complex polysaccharides in their diet. Members of the family Termitidae lack the protozoa, although bacteria are present which assume the same digestive function.

In times pasl in Brazil, large, hard termitaria have been hollowed out and used for ovens (Southy, in Cowan 1865: 134). The same nests were pulverized and used as a kind of cement to make "concrete" floors for the early settlers of this land.

There is just one review of Neotropical termites (Araujo 1970). In the Neotropical region, there are sixty-two genera, containing 408 species (Araujo 1970, 1972, 1977). Most belong to the family Termitidae. General information on these insects is available in Krishna and Weesner (1969-70). Very useful bibliographies of termite literature to 1978 have been compiled by Snyder (1956, 1961, 1968) and Ernst and Araujo (1986).

References

Araujo, R. L. 1970. Termites of the Neotropical Region. In K. Krishna and F. M. Weesner, Biology of termites. 2: 527-576. Academic, New York.

Araujo, R. L. 1972. Sumula faunistica dos Isop-tera americanos. Cien. Cult. 24(3): 253—256.

Araújo, R. L. 1977. Catálogo dos Isoptera do novo mundo. Acad. Brasileira Cien., Rio de Janeiro.

Cowan, F. 1865. Curious facts in the history of insects. Lippincott, Philadelphia.

Deligne, J., A. Quennf.dey, and M. S. Blum. 1981. The enemies and defense mechanisms of termites. In H. R. Hermann, Social insects. 2: 1-76. Academic, New York.

Ernst, E., and R. L. Araújo. 1986. A bibliography of termite literature 1966-1978. Wiley & Sons, Somerset, N.J.

Kistner, D. H. 1969. The biology of termito-philes. In K. Krishna and F. M. Weesner, Biology of termites. 1: 525-557. Academic, New York.

Krishna, K., and F. M. Weesner. 1969-70. Biology of termites. 2 vols. Academic, New York.

Lacher, Jr., T. E., I. Egler, C. J. R. Alho, and M. A. Mares. 1986. Termite community composition and mound characteristics in two grassland formations in central Brazil. Bio-tropica 18: 356-359.

Lee, K. E., and T. G. Wood. 1971. Termites and soils. Academic, London.

Magnusson, W. E., A. P. Lima, and R. M. Sam-paio. 1985. Sources of heat for nests of Paleo-suchus trigonatus and a review of crocodilian nest temperatures. J. Herpet. 19: 199-207.

Matthews, A. G. A. 1977. Studies on termites from the Mato Grosso State, Brazil. Acad. Brasileira Cien., Rio de Janeiro.

Noirot, C. 1977. Nest construction and phylog-eny in termites. 8th Int. Union Study Soc. Ins. (Netherlands 1977) Proc. Pp. 177-180.

Prestwich, G. D. 1983a. Chemical systematics of termite exocrine secretions. Ann. Rev. Ecol. Syst. 14: 287-311.

Prestwich, G. D. 19836. The chemical defenses of Termites. Sei. Amer. 249: 78-87.

Redford, K. H. 1984. The termitaria of Cornitermes cumulans (Isoptera, Termitidae) and their role in determining a potential keystone species. Biotropica 16: 112-119.

Snyder, T. E. 1924. Damage by termites in the Canal Zone and Panama and how to prevent it. U.S. Dept. Agrie. Dept. Bull. 1232: 1-25.

Snyder, T. E. 1956. Annotated, subject-heading bibliography of termites 1350 b.c. to a.D. 1954. Smithsonian Misc. Coll. 130: 1-305.

Snyder, T. E. 1961. Supplement to the annotated, subject-heading bibliography of termites 1955 b.c. to a.D. 1960. Smithsonian Misc. Coll. 143: 1-137.

Snyder, T. E. 1968. Second supplement to the annotated subject-heading bibliography of termites 1961-1965. Smithsonian Misc. Coll. 152(3): 1-188. Wolcott, G. N. 1957. Inherent natural resistance of woods to the attack of the West Indian dry-wood termite, Cryptotermes brevis Walker. J. Agric. Univ. Puerto Rico 41: 259-311.

Zimmerman, P. R., J. P. Greenberg, S. D. Wandiga, and P.J. Crutzen. 1982. Termites: A potentially large source of atmospheric methane, carbon dioxide, and molecular hydrogen. Science 218: 563-565.

Nasute Termites

Termitidae, Nasutitermitinae, Nasutitermes. Spanish: Comejenes comun (General).

The large (1—2 m diameter), round or ovoid, dark brown nests of these ubiquitous tropical termites punctuate the moist lowland landscape throughout Latin America (fig- 5.13f, pi. 4a). They are constructed of a paste of chewed wood and fecal cement put into place by myriad workers. The paste hardens into a carton substance that is soft and papery on the outside and increasingly harder toward the inside. The outer envelope is continuous, forming a protective shell for the labyrinthine interior. Nests undergo continual expansion during their existence (Jones 1979).

Runways, covered with this same carton substance, lead from the main nest to remote foraging sites. These tunnels end abruptly on the surfaces of dead wood which the workers penetrate to feed. The presence of these runways is what distinguishes termite nests from the other arboreal paper or carton ant and wasp nests with which they are often confused. Not all species build such elevated structures; some, such as Nasutitermes fulviceps, live on the soil surface and are partly subterranean (Talice et al. 1969).

The tunnels may also lead to fence posts, telephone poles, and the founda-Uons of houses, whose substance is devoured with equal gusto. Consequently, these termites are considered pests and often require control. The evidence for a beneficial role for Nasutitermes as nitrogen fixers is inconclusive (Bradley et al. 1983).

The soldiers are best known and are usually seen when they appear at the surface of nests that are being damaged. They are small (BL 3-4 mm), with brownish, pigmented bodies and dark brown heads bearing a conspicuous, elongate beak on the fronl (fig. 5.13e). They also possess an effective chemical defense. When a break occurs in the nest surface, they immediately swarm to the site and remain there until the intruder leaves or until they are ravished. As a means of repelling attackers, they ooze or squirt an irritating, thick, entangling substance (nasute glue) from their long pointed snouts. This sticky, smelly secretion is produced by large glands in the head and contains volatile terpenoids (Prestwich 1982). It is used mostly against other insect invaders of the colony but is effective also in warding off the attacks of termitophagous vertebrates, including anleaters (Tamandua, Myr-mecophaga). These chemicals are topical irritants thai affect the skin and mucous membranes of the nostrils and mouth (Lubin and Montgomery 1981). Incursions by animals and the formation of nest holes by trogons, parakeets, and other birds often do considerable damage to nests and may force abandonment by their occupants. Ants of the genus Azteca are sometimes found living within Nasutitermes nests and may exclude the owners from their rightful home.

The workers (fig. 5.13d) are about the same size as the soldiers but have a round head, are pale, and generally remain deep within the nest, caring for young and the queen, even during times of outward threat. Although workers have no special weapons, they can bite effectively and sometimes join with the soldiers in aggressive encounters, especially against other termites (Thorne 1982).

Queens may attain great size (BL 3—6 cm) by the enlargement of the abdomen with fat and eggs. Normally, there is one per colony, but Nasutitermes corniger is known to be facultatively polygynous (multiple queens) (Thorne 1982).

Members vary greatly in number, usually from five thousand to six thousand, depending on age, species, and health of the colony. But much more numerous populations are possible. Some Nasutitermes corniger nests may contain 800,000 to a million individuals (Thorne and Noirot

1982, Laffitte and Aber de Szterman 1976).

Reproduction is seasonal. Swarming of the winged male and female reproductive stages usually occurs after the first showers of the incipient rainy season and may continue for many months into the wet part of the year.

Many of the sixty-seven Neotropical species of Nasutitermes place their nests in trees, or at least off the ground in shrubby vegetation. The walls of the rare terrestrial nests are shown to contain nutrients in excess of the surrounding soil, thus concentrating substrate richness for plant growth and contributing to patchy vegetation patterns in the Amazon Basin (Salick et al.

1983, Goodland 1965). General information on the genus is sparse (Lubin 1983, Araujo 1970).

References

Araljjo, R. L. 1970. Termites of the Neotropical Region. In K. Krishna and F. M. Weesner, Biology of termites. 2: 527—576. Academic, New York.

Bradley, R. S., L. A. de Oliveira, and A. Gomez Bandeira. 1983. Nitrogen fixation in Nasutitermes in central Amazonia. In P. Jaisson, Social insects in the tropics. 1st Int. Symp. (Cocoyoc 1980), Int. Union Stud. Soc. Ins. and Soc. Mexicana Entomol. Proc. 2: 235-244. Goodland, R. J. A. 1965. On termitaria in a savanna ecosystem. Can. J. Zool. 46: 641—650. Jones, R. J. 1979. Expansion of the nest of

Nasutitermes costalis. Ins. Soc. 26: 322—342. Laffitte, S. and A. Aber de Szterman. 1976. Comportamiento interespecifico en Nasutitermes fulviceps (Silvestri, 1901) con otras termites. Rev. Biol. Uruguay 4: 59-65.

Lubin, Y. D. 1983. Nasutitermes (comején hormiga blanca, nasute termite). In D. H. Janzen, ed., Costa Rican natural history. Univ. Chicago Press, Chicago. Pp. 743-744.

Lubin, Y. D., and G. G. Montgomery. 1981. Defenses of Nasutitermes termites (Isoptera Termitidae) against Tamandúa anteaters (Edentata, Myrmecophagidae). Biotropica 13: 66-76.

McMahan, E. A. 1970. Radiation and the termites at El Verde. In H. T. Odum, ed., A tropical rain forest: A study of irradiation and ecology at El Verde, Puerto Rico. U.S. AEC, Washington, D.C. Pp. E-105-122.

Prestwich, G. D. 1982. From tetracycles to marcocycles: Chemical diversity in the defense secretions of nasute termites. Tetrahedron 38: 1911-1919.

Salick, J., R. Herrera, and C. F.Jordan. 1983. Termitaria: Nutrient patchiness in nutrient-deficient rain forests. Biotropica 15: 1—7.

Talice, R. V., S. L. Mosera, R. Caprio, and A. M.S. de Sprechmann. 1969. Estructura de los termiteros. Univ. Uruguay, Dept. Biol. Gen. Exper. Publ. 2: 1-20.

Thorne, B. L. 1982. Termite-termite interactions: Workers as an agonistic caste. Psyche 89: 133-150.

Thorne, B. L. 1982. Polygyny in termites: Multiple primary queens in colonies of Nasutitermes corniger (Motschuls) (Isoptera: Termitidae). Ins. Soc. 29: 102-117.

Thorne, B. L., and C. Noirot. 1982. Ergatoid reproduction in Nasutitermes corniger (Mot-schulsky): Isoptera, Termitidae. J. Ins. Morph. Embryol. 11: 213-226.

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