As the universe faces an increasing nutrient scarceness, the biggest challenge for agricultural universe is to heighten the nutrient productiveness to carry through this increased demand. About 35 % of universe agricultural merchandises is lost from pest onslaught due to insects, fungus, viruses, and bacteriums, a expert plague control plan is an of import section needed for any attempt to increase the harvest outputs. The uninterrupted effort between human and his insect plague enemies started even before the start of civilisation. Alternatively the big figure of new techniques introduce by adult male in developing new and deathly interventions to contend the war against insects, but he has non been successful in commanding even one of the 1000s of serious insect plagues which amendss his nutrient and other agricultural harvests, destroys his belongings and even assail himself and wound his domestic animate beings.
Many of the chemical insect powders and pesticides that are presently used to command insect plagues are earnestly poisionoius to non-target beings and may besides be harmful for the human and carnal wellness. These toxic chemicals besides pollute H2O and dirts, as most of the pesticides are fractious to breakdown. Furthermore, by utilizing these chemicals in high measure, most of the insect acquiring opposition to different pesticides.
Naturally the insect exist reprieve between the insect and worlds, and this is known as ‘balance in nature ‘ . There are two opposing phenomenon are responsible for this balance, one one of them is the ‘biotic possible i.e. the higher capacity of insect plagues to reproduce and multiply and environment opposition by which their Numberss are kept under cheque. The environment opposition can do the decease of grownups before in the mortality of eggs, oviposition, pupae or larvae of the insects because of parasites, famishment, dehydration, diseases, marauders, and other unfavourable environmental factors.
The efforts to command insect by human have changed with paasage of clip from biological methods to unreal chemical control, and one time once more, we are intrested to command these insect of course. But the pesticides we are utilizing now are relatively more safe and less toxic than those used in the past, such as DDT, which can still a cause for concern. Long-run use of these man-made pesticides has been releated with liver harm, immunotoxicity, malignant neoplastic disease, generative jobs and birth defects in worlds and other animate beings ( Kegley and Wise, 1998 ) .
The undesireable consequences of green revolution include construct up the residues of loosely used man-made pesticides in assorted environmental mechanisms. Several surveies showed that insect powder can do serious wellness pproblems such as malignant neoplastic disease, birth defects and nervus harm. ( Rekha et al. , 2005 ) . Several types of pesticides and their country of consequence are given in table 1. And Major states utilizing high dose of pesitcides are mentioned in table 2.
Table 1. Types of man-made pesticides and their country of consequence
Area of Effect
DDT, Dieldrin, Toxaphene, Aldrin
Generative, nervous, endocrinal, and immune system
Glyphosate, Diazinon, Malathion
Central nervous system
Aldicarb, Carbofuran, Carbaryl
Central nervous system
Deltamethrin, Fenpropanthrin, Cypermethrin
Table 2. Major states utilizing high dose of pesticide
Pesticide used kg/hac
NationMaster ( 2002 )
1A·5 million tones of man-made insect powders are produced every twelvemonth, which accounts for a concern worth US $ 30 billion ( McKenzie, 2001 ) .Pakistan produces 8,350A bales of cotton annualy and ranks 4th in universe cotton production ( Nation Master, 2004 )
After the debut of DDT in the 1940s, insect plagues are control about extensively with chemical pesticides ( Casida and Quistad 1998 ) . Comparitivly easy to present, rapid action, and cheap to bring forth, extremely effectual chemical insect powders have been studied with intense optimism ; jobs associated with these chemicals did non get down to go evident to most scientists until about two decennaries after their first usage. These restrictions included low species specificit, which leads to losingss in some utile insect species, disequilibrium of ecosystems consequences in lift of minor plagues to major plagues, produces toxicity in vertebrate species including fish, mammals, and birds and opposition develops in mark beings.
Such opposition has been increased by the cut downing handiness of many man-made chemicals, which enhance the regulative limitation of insect powder usage ; market remotion of insecticides no longer registered for public wellness usage, and reduced net incomes of certain compounds. The combination of these factors consequences in world-wide pest-induced losingss of nutrient, provender and fibre of several billion dollars each twelvemonth Elzen and Hardee, ( 2003 ) . Tedford et al. , ( 2004 ) described the development of opposition to many pesticides along with increased consciousness of the possible environmental and human and carnal wellness impacts of these chemicals
Most of the insect powders are toxic to human existences ; WHO ( universe wellness organisation ) has classified their toxic effects into three categories from category Ia ( highly toxic ) to category III ( somewhat toxic ) and so “ their active component improbable to show acute jeopardy ” ( Anonymous, 2001 ) . Harmonizing to study most insecticide deceases recorded in infirmary, which are found to be self poisoning the human ( Eddleston, 2000 ) . The world-wide Burden of disease study showed that 798 000 people died from concious self-harm in 1990, and more than 75 % of them were from undevloped states ( Murray and Lopez, 1996 ) . .More recent WHO surveies showed that over 500,000 people died from ego toxic condition in the western Pacific and Southeast Asia during 2000 entirely ( Anonymous, 2001 ) . Suicide is the most common ground of decease in immature Chinese adult females and Sri Lankan work forces and adult females ( Murray and Lopez, 1996 ; Anonymous, 2001 ; Anonymous, 1997 ) . Insecticides are the most of import method of ego poisoning in many rural countries and are linked with a high decease rate ( Eddleston, 2000 ) .
The insect powder containig organochlorine is polluting the nutrient merchandises which is serious menace to the human offspring. ( Bakore et al. , 2004 ) . Recently, the experiments at the Central Cotton Research Institute ( CCRI ) , Multan, showed that the two major cotton plagues, the American the whitefly and bollworm have developed opposition against common insect powder. Ahmad et al. , ( 2007 )
The outgrowth of insecticide opposition in insect populations, every bit good as increased hazard about the human wellness and environment are linked with certain agrochemicals, has encouraged the hunt for new arthropod-control attacks.
In cotton, veggies and tobacco bulk of insects showed opposition to insect powders ( Rajmohan, 1998 ) . Helicoverpa armigera ( which is one of the most serious insect plague on cotton, cereals, veggies and leguminous plants ) has shown opposition to many groups of agrochemicals in tomato, chilis, pigeonpea, cotton, Indian potato, garbanzo and helianthus. The outgrowth of opposition against top inesticides has imposed the application of higher doses of the same insect powder or increased figure of insecticide applications.
Bt Plant pesticides
The development of opposition to many pesticides, along with increased consciousness of the possible homo, environmental and carnal wellness impacts of these man-made chemicals, has encouraged the hunt for new insecticidal compounds, new molecular marks, and alternate control methods ( Tedford et al. , 2004 ) .
The Bt plant-pesticide named as Bt field maize, was foremost registered with the United States Environmental Protection Agency in 1995 ( USEPA, 1999 ) . In the US, less than 2 % of the market, sprayable Bt preparations have been used in cotton, vegetable and fruit, aquatic, and other insect powder markets, and in the last few old ages new Bt preparations have continuously grown in a few fruits and forte vegetable markets ; Bt has remained the ) . Table 3 indicates different types of Bt biopesticides and the insects control by these biopesticides
Table 3. Types of Bt biopesticides and the insects control by these biopesticides.
Bt Biopesticide ( merchandise name )
Biobit, Dipel, MVP, Steward, Thuricide
Tent caterpillar, Fall webworm. , Leafroller, Redhumped caterpillar, Spiny elm caterpillar, Western spruce budworm. , Pine budworm, Pine butterfly, Cabbage worm, Tomato and baccy hornworm, Leafroller, European maize bore bit, Alfalfa caterpillar, alfalfa webworm.
Vectobac, Mosquito Dunks, Gnatrol, Bactimos
Mosquito, Black fly, Fungus gnat
San diego/tenebrionis strains
Trident, M-One, M-Trak, Foil, Novodor
Colorado murphy beetle, Elm leaf beetle, Cottonwood leaf beetle.
4. Bt TRANSGENIC CROPS:
Major Bt transgenic workss include cotton, maize, rice, and murphies. The look of Bt delta-endotoxins in transgenic harvests has been much more helpful against insects that can assail parts of the works which may non well-protected by typical pesticide application. ( Ely, 1993 ) .
Gatehouse ( 2008 ) explain that Insect resistant in harvests are one of the most successes of initiation works familial technology engineering to agribusiness ; cotton ( Gossypium hirsutum ) which showed resistant to lepidopteran larvae and maize resistant to both lepidopterous insect and coleopteran larvae ( rootworms ) that is now used worldwide in agribusiness and have led to minmize the pesticide use which besides minimize cost of production ( Toenniessen et al. , 2003 ; Brookes and Barfoot, 2005 )
The major beginning of the insecticid toxins produced in commercial transgenic harvests is the dirt born Bacillus thuringiensis ( Bt ) . Bacteria of Bt show changing specificities of insecticidal activity toward insects, and represent a big reservoir of cistron pool which encodes for protiens produced by insect powders, which are accumulated in the crystalline strucutre which are produced by the bacteriums on monogenesis ( Cry proteins, Cyt proteins ) or expressed during bacterial vegetive growing ( Vip proteins ) . There are three spheres of Cry proteins have been exhaustively studied ; the mechanism of action includes a proteolytic activation measure, which is occured in the insect intestine after ingestiono nutrient, followed by interaction of either one or two of spheres II and III with receptors, on the outer surface of the insect intestine epithelial tissue cell. This interaction may take to oligomerization of the protein, and sphere I is responsible for the devlopment of an unfastened channel via the cell membrane. This consequences in ionic escape can destruct the cell, which may do the dislocation of the intestine, bacterial proliferation, and eventually do devastation of the insect. Devloped states turning GM harvests are mentioned in table 4.
Table 4. Major states turning different GM harvests
Area ( million hectares )
Soy, Maiz, Cotton, Canola, Squash, Papaya, lucerne,
Soy, Maiz, Cotton
Soy, Maiz, Cotton
Soy, Maiz, Canola, Sugarbeet,
Cotton, Tomato, Poplar, Petunia, Papaya, Sweet murphy
Maize, Soybean, Cotton
Cotton, Canola, Carnation
( ISAAA Executive Summary 2008 )
Bacillus thuringiensis is known as Gram-positive bacteria which is widely used in agribusiness sector as a bio-pesticide. The biocidal activity of Bt chiefly exist in a parasporal protein inclusion organic structure, or crystal. The inclusion is composed of one or few types of delta-endotoxins ( Cry and Cyt proteins ) . Cry proteins are largely toxic to different spiecies from spineless phyla: arthropods ( chiefly insects ) , platyhelminths, roundworms, and Protozoa. ( Prieto-Samsonov et al. , 1997 ) .
Up till now more than 34 races of B. thuringiensis have been recognized, some of the most knowb are used, include races kurstaki ( active against Lepidoptera ) , races israelensis ( active against Diptera, chiefly mosquitoes and bean aphids ) , and races tenebrionis ( which is against Leptinotarsa decemlineata, the Colorado murphy beetle ) ( Whalon and McGaughey, 1998 ) . There are different types of protiens active against the type of insects and some active protiens studied against insects are given in table 5 and 5.1 repectivly.
Table 5. Different proteins active against insect
Hofte and Whiteley ( 1989 )
Lepidoptera and Diptera
Very important person
Yu et al. , 1997
Protease inhibitors or Ribosome inactivating
expressed in transgenic to environmental stimuli workss in a
tissue or development-specific mode, or in response
( Boulter, 1993 ;
Sharma et al. , 2004 )
active against dipterous insect and coleopteran plagues, and furthermore have shown affects against hemipterous insects ( true bugs ) and dictyopterans ( roaches and white ants )
( Frutos et al. , 1999 ; Gould and Keeton, 1996 )
Lepidopteran insects ( Helicoverpa armigera and Spodoptera littoralis caterpillars )
Khan et Al. ( 2006 )
Table-5.1: Some active proteins studied against insects