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For educational purposes:--

Information on the basics of Entomology

 

Introduction                                                                                                                                                                                                                                                                                         Contents

 

An Introduction To The Study of Entomology 1

Kingdom:  Animalia, Phylum: Arthropoda

Subphylum: Hexapoda: Class: Insecta: Order: Isoptera

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Pteragota:  Paurometabola

   Order:  Isoptera (7 Families)

      General Summary

      Termite Habitats

      Nutrition

      Termite Castes

      Reproduction

      Control

      References      Citations

Sample Examinations

 

General Summary of Isoptera

 

          Isoptera, which means "equal-wings", are social and polymorphic insects with biting mouthparts, four-lobed ligula, wings that are very similar elongated and membranous and capable of being broken off along a line at the base.

 

 

           Their cerci are short.  Metamorphosis is simple.  They, like some Hymenoptera, have a social organization.  Termites abound everywhere in the tropics where they cause extensive damage to wood products.

 

Termite Habitats

 

           The termite nests may be simply series of burrows in trees, dry timber or in the ground, or they may be huge mounds made of earth cemented together with the saliva of the termites. Those living in the ground excavate the soil of the tropics, turning it over and enriching it just as earthworms do in temperate regions. Others may remove permanently from the soil much of its organic matter.  Their food consists mostly of wood and other vegetable matter and many species are extremely harmful, e.g. Neotermes, which damages human structures, and Calotermes militaris, which bores into and does much harm to tea plants in Ceylon (Borradaile & Potts, 1958). Many species of termites reduce dead wood to organic soil material and thereby make agriculture possible in some areas.  However, termites are in competition with humans for wood through their damage to buildings.  They are of greatest importance in warmer regions.

 

          There are basically two types of termites:  subterranean and dry wood.  Subterranean termites are soft bodied with a thin cuticle.  They obtain moisture from the soil or metabolic processes.  They are more organized than the drywood type.  They also modify their habitats by constructing tubes in their foraging activities for food.  Mounds, called termitaria, are constructed in some areas.   These often reach heights of one or two meters, and they are oriented to a north and south direction for heating purposes.  Nests are sometimes built in trees, although these are smaller.  They may contain fungus chambers.

 

          Dry wood termites confine their nests to the wood that they depend upon for food.  They are widespread and cause considerable damage to wooden houses and the wood products contained therein (chairs, tables, etc.).

 

Nutrition

 

          Termites usually forage by night for plant food, and members of the subfamily Microtermitinae cultivate fungus gardens in special galleries. The fungus, which grows on a bed of chewed vegetable matter, serves as the food for the royal pair and the nymphs.  Their principal food is cellulose, which is digested by flagellated Protista symbionts (Zoomastigina) in their gut.  These symbionts are passed on in two ways:  (1) regurgitated liquid food and (2) excrement.  Protein is obtained by eating dead termites.

 

          Digestion and growth of wood-eating termites can only proceed when flagellate fauna occur in the hindgut. The fragments of wood are ingested by the flagellates and converted into sugars, being for the most part stored in the form of glycogen. The termite requires the metabolic services of the flagellates to render the food available, and in return provides the anaerobic conditions that the flagellates are known to require.

 

Termite Castes


          Like the true ants termites have different types of individuals that are
specialized for the purpose of reproduction, labor and defense.  The termite community usually contains a wingless royal pair:  the king and queen, who are the founders of the colony, and also additional reproducing individuals of two kinds: (1) winged that usually serve for the formation of new colonies, and (2) wingless, which develop reproductive capabilities if conditions are demanding.  There are usually a vast number of sterile wingless individuals belonging to worker and soldier castes.  There are also nurses that gather nutrients, prepare it and serve it.   The workers and soldiers differ from the sexual individuals, not only in their sterility, but also in having more powerful mandibles. In the soldiers the head can produce a protective secretion and the mandibles are greatly specialized for defense.  Both these castes consist of males and females, though secondary sexual characters are not very marked.  Casts probably do not form because of nutritional stimuli, as slight caste differences are apparent in newly hatched young.  Secondary and tertiary sexual forms may appear as reserves.

 

 

          The mandibles and head of worker termites are modified to produce enlarged forceps-like mandibles, snout-shaped structures and plug-shaped structures.

 

 

          Some of the more primitive termite species have only two castes:  reproductives and soldiers.  Immature individuals of these two castes perform work in the colony.

 

Termite Reproduction

 

          When conditions such as high humidity, light intensity, ample food and overcrowding are present, wings are produced and functional males and females develop.  These leave the colony, and the winged sexual forms in several colonies usually swarm at the same time, so enabling intercrossing between members of different colonies to take place, and of the immeasurable numbers, a few individuals escape the attacks of birds and other animals and alight and cast their wings.

 

          The insects pair in flight and then drop to the ground to seek a nesting site at the discretion of the female.  They lose their wings, mating takes place and unlike other insects, the male remains with the female and frequent mating takes place.  Soon after mating the female loses all capacity other than egg laying, and a single pair forms a new colony first of all by making a small burrow, the nuptial chamber. The first-formed young are mostly workers and, having themselves been tended to maturity by their parents, take over the nursing of the young. The queen becomes massive and helpless and is fed by the workers; she lays eggs at an unbelievable rate of over one million eggs annually.

 

Termite Control

 

          Eliminating termites from dwellings can be an expensive undertaking especially if they are widespread within.  Tenting and fumigating is the usual procedure that is required by law in some areas when houses are sold.  Nevertheless, this is not a permanent solution, as reinvasion will inevitably occur.  Spot treatment of infested beams can be achieved with pressurized aerosol insecticides available on the open market.  However, it is essential to penetrate the entire colony.  Small blackish beadlike droppings below infested beams are indicative of their presence somewhere above.  Temperature influences their movements in the beams:  high temperatures cause them to descend to lower, cooler levels and low temperatures cause them to seek out warmer areas.

 

          Preventative measures can be taken by shielding wood surfaces with metal flashings, especially where these touch the ground, and by treating outdoor wood with preservative chemicals (e.g., creosote).

 

          Swarming by alate adults in the North American Southwest occurs during late springtime.  It is not uncommon to see local lizards consuming them at a rapid rate as they emerge from their colonies.  Where the feeding is very extensive it undoubtedly has a significant impact on the termite populations.  Also, the Argentine ant has been associated with declines in termite populations in the Riverside, California area.  The ants have been observed feeding on dieing alate termites, but other associations have to be investigated to account for the reductions in structure infestations.

 

 

Details of Insect Taxonomic Groups

 

          Examples of beneficial species occur in almost every insect order, and considerable information on morphology and habits has been assembled.  Therefore, the principal groups of insect parasitoids and predators provide details that refer to the entire class Insecta.  These details are available at <taxnames.htm>.

 

 

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References

 

Introduction                                                                                                                                                                                                                                                                                                 Contents