CROPS GROWN IN PAKISTAN

Introduction          

Pakistan is situated between the latitudes of 24 and 37 north and longitudes of 61 to 75 east . Stretching over 1600km from north to south and 885km from east to west, with a total area of 796095 square kilometres. It has a subtropical and semi arid climate. The annual rainfall ranges from 125mm in the extreme southern plains to 500 to 900mm in the sub mountainous and northern plains.

About 70% of the total rainfall occurs as heavy downpours in summer from July to September, Originating from the summer monsoons and 30% in winter summers except in the mountainous areas, are very hot with a maximum temperature of more than 40C, while the minimum temperature in winter is a few degrees above the freezing point.

Order Isoptera

Introduction

               Isoptera are small, soft-bodied, yellowish, whitish, tan or black insects that live in colonies in wood. Colonies consist of three castes: workers, soldiers and swarmers . Workers and soldiers are wingless and never leave the colony. Swarmers , or the reproductive forms, have dark bodies and four long, veined wings. The front and hind wings of termites are nearly identical in size and venation. Termites also have beadlike antennae and thick waists which distinguish them from ants.

            The name Isoptera, derived from the Greek "iso" meaning equal and "ptera" meaning wings, refers to the similar size, shape, and venation of the four wings. Isoptera also called Isoptera or Termites.

          Termites are usually the most dominant organisms in tropical forest environments.  Their populations typically range from 2000 to 4000 individuals per square meter but may occasionally run as high as 10,000 individuals per square meter.

Scientific Classification of Isoptera

Kingdom: Animalia

Phylum: Arthropoda

Superclase: Hexapoda

Class:  Insecta

Subclass: Pterygota

Infraclass: Neoptera

Order: Isoptera

Distribution

}  Extremely common in tropical and subtropical climates.  Generally less abundant in temperate regions.

}  Isopteran are hemimetabola(egg, nymph, adult)

Characteristics of Isoptera(Termites)

Ø  Pale, elongate body

Ø  2 pairs of membranous wings of equal length. Wings are present in reproductive castes only and shed after mating

Ø   Mandibulate(chewing) mouthparts

Ø  Antennae about the same length as the head

Physical Features 

Immatures (Workers & Soldiers)

         

              Body pale in color, somewhat ant-like in appearance but with a broader junction between thorax and abdomen Compound eyes small or absent.

Ø  Head large and cylindrical or small and round.

Ø  Antennae beaded.

Ø  Mouthparts chewing; sometimes with large mandibles.

Adult

Ø  Body may be darkly pigmented Head well-developed, with chewing mouthparts and beaded antennae.

Ø  Compound eyes present.

Ø  Two pairs of membranous wings, all similar in shape and size; wings are shed after mating.

Feeding

         Termites feed on a wide variety of plant material, which may include wood, bark, leaves, grasses, fungi, humus or the droppings of herbivores. Some species forage on the surface at night collecting grasses which they take back to be stored in the nest.

Families of order Isoptera

             There are 7 families present worldwide with more than 2300 species.

Important families of isoptera

}  In 7 families of order isoptera that is only 4 families are very important  which are as follows.

v  Rhinotermitidae (Subterranean termites)

v Kalotermitidae (Drywood and dampwood termites)

v  Hodotermitidae (Rottenwood termites)

v  Termitidae 

Family: Rhinotermitidae (Subterranean termites)

}  These insects build nests in the soil and generally infest wood that is in contact with the ground. 

}   This family includes the most destructive species

Family: Kalotermitidae  (Drywood and dampwood termites)

}  These insects nest in the wood itself and do not require contact with the soil.  Pest species include the western drywood termite (Incisitermes minor) and the forest tree termite (Neotermes connexus)

Family: Hodotermitidae  (Rottenwood termites)

             Generally found inhabiting moist wood.   Contact with the soil is not a requirement.  This family includes the Pacific dampwood termite, Zootermopsis angusticollis.

Family: Termitidae

}  This is the largest family of termites worldwide, but all of the North American species are relatively minor in importance.

}  Adults have three or four heavy veins along the front edge of the wing, the cerci have five or six segments and the antennae have 20 or more segments.

Conclusion

           Termites are an important part of the community of decomposers.  They are abundant in tropical and subtropical environments where they help break down and recycle up to one third of the annual production of dead wood.  Termites become economic pests when their appetite for wood and wood products extends to human homes, building materials, forests, and other commercial products.  In the United States alone, annual losses due to termite infestations are estimated at more than 800 million dollars. 

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