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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: Order: Thysanoptera

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Pteragota:  Paurometabola

  Order:  Thysanoptera (15 Families)

    General Summary

    Habits

    Economic Importance

  Biological Control Projects

  Sample Examinations

    References      Citations

 

General Summary of Thysanoptera

 

          The Thysanoptera -- <Adults> & <Juveniles> -- are tiny insects, 0.5 to 12 millimeters, with asymmetrical piercing rasping-sucking mouthparts and a short labial proboscis.  Their prothorax is large and free.  The tarsus has two or three joints with a terminal extendable vesicle.  Both winged and wingless forms occur.  When present there are two pairs of similar wings, provided with a fringe of prominent long hairs, which appear as feathers, and few veins if at all are present. 

 

          Metamorphosis is more complex than most insects and it includes an incipient pupal instar.  Instar 1 and 2 are simple with no wing pads.  Instar 3 has wing pads.  The 4th instar is quiescent and changing enclosed in a cocoon.

 

Habits

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          These insects are general plant feeders, but a few are also carnivorous. They are regarded as serious pests in that they feed on plant sap.  They can also cause malformations and in some instances inhibit fruit development.

  

          Parthenogenesis is of common. In the pea thrips, Kakothrips robustus, the eggs are inserted in the stamen sheath of the flower and the nymphs emerging feed on the young fruit, inhibiting its growth. Later they feed on the soft tissues of pea pods, causing scar-like markings. The nymphs leave the plant and bury themselves deeply in the ground, where they remain until the following spring, when they pupate. Common thrips in Europe are Taeniothrips inconsequens of pears and Anaphothrips striatus of grasses and cereals (Borradaile & Potts, 1958).

 

Economic Importance

 

          Their direct feeding activity gives plant leaves a silvery appearance.  They are able to transmit the Spotted-wilt virus to tomatoes.  The citrus thrips and gladiola thrips are very destructive, the latter damaging the corms in storage.  The bean thrips feed on the leaves of cotton and beans.  They are also very important pests of pears where they attack the flower buds and prevent their development. 

 

          The onion thrips attacks a wide range of plants.  It causes a distortion to the foliage of onion and is especially serious on onion seed crops.  It fees mostly on the leaf sheath, but will also attack the blossoms.  The males are wingless, but females have wings and they reproduce parthenogenetically.  The gestation period is only 20 days.

 

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Thysanoptera --Biological Control Projects (1% of total projects)

 

          Cuban Laurel Thrips, Gynaikothrips ficorum Marchal <ch-36.htm>

 

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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