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For educational purposes:--

Information on the basics of Entomology

 

Introduction                                                                                                                                                                                                                                                                   Contents

 

An Introduction To Entomology 1

Kingdom:  Animalia, Phylum: Arthropoda

Subphylum: Hexapoda: Class: Insecta: Entomology

Systematics

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Systematics

  Historical Review

  Modern Classification System

  Orders of Insects

Details of Insect Taxonomic Groups

  References      Citations

  Sample Examinations

Table 1 (Contents)

 

Historical Review

 

          The procedure of modern systematics was begun in 1958 when the Swedish botanist, Linnaeus, published Systema Naturae.  it established the binomial system for naming organisms.  The 10th edition of this publication established Systematics for Zoology.  An organism thereafter was given a generic plus a species name.  Also permissible under this system are various interspersed gradations such as subspecies, subfamily, superfamily, etc.

 

          There is never more than one Genus name; however, there may be synonymous species names.  Also, an abbreviation of the name of the person who described the species is designated as, for example:

 

          Genus species Linn. = Linnaeus described the organism in the Genus as written.

 

          Genus species (Linn.) = Linnaeus described the organism, but he had placed it in a different Genus.

 

          Law of Priority. -- This states that the first name given to a species is preferred if it is later described under another name.  The later name for the same species is than called a synonym.

 

          Common Name System. -- This is used as a substitute for the names of orders and families, as, for example, beetles, locusts, etc.  It applies to a segment of an order.  However, scientific names are more valuable in international discourse.

 

          Characters Used For Classification. -- Three principal characters that are used for classifying an organism are (1) morphological, which includes structure of the wings and mouthparts, (2) physiological, such as metamorphosis, and (3) Paleontological, where there may be fossil data.  But the latter is not very extensively used in classification because insects are not too abundant as fossils although they were present over 300 million years ago.

 

          Periodic Name Changes. -- Changes in both the genus and species names of insects are found throughout the literature, causing some confusion when older references are consulted.  Also certain authors may not accept a name change and will continue to refer to an insect by its older name.  A famous example is that of the cottony-cushion predator, Rodolia (Novius) cardinalis that startled the entomological world when it was deployed successfully in biological control.  Present literature may refer to either of the generic names noted here.

 

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Modern Classification System For Hexapoda

 

          Two principal subdivisions are (1) Apteragota, which are the primitively wingless forms that never bore wings in antiquity and (2) Pteragota, which includes all those presently bearing wings or which had wings in antiquity.  The latter is evident from the vestiges of sclerites (plates) that appear on their pleural regions of the thorax.  Only one order, Thysanura, is presently assigned to this category.  Previously members of the Class Entognatha were classified with the Insecta, which includes the orders Collembola, Diplura and Protura.

 

          The Apteragota show no metamorphosis (Ametabolous).  On the other hand, Pterogota embrace forms that show incomplete metamorphosis (Hemimetabolous) and complete metamorphosis (Holometabolous and Paurometabolous)

 

          The Apteragota are further subdivided into forms with recessed mouthparts (Entotrophi) and exposed mouthparts (Exotrophi).  The genae are responsible for covering the mouthparts.  All Apteragota possess only one pivot point on the mandibles.

 

          The Pteragota are subdivided into general nameless categories, which take into consideration the presence of one or two mandibular pivots, with the former being primitive.  The primitive venation is one with numerous crossveins while the more evolved condition is a reduced venation.  A sideward extension of the wings is more primitive than the more evolved folded wings.

 

          Linnaeus described insects in only seven orders:  Hymenoptera, Coleoptera, Lepidoptera, Diptera, Hemiptera, Aptera and Orthoptera.  Subsequently additional orders were designated as the study of Entomology progressed, until as of 2010 there are twenty-four (See Orders).

 

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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