INTRODUCTION:

Phytochemicals are compounds which are produced by plants. Phytochemicals is mostly used to describe a number of compounds that occur naturally in plants. Phytochemicals are compounds which are having a certain biological activity against the pests. ThePhytochemicals are obtained from the plant itself which act against the most common pests of our crops and vegetables. Phytochemicals called as the research compound. Phytochemicals is a wide term Phyto means plant and chemicals called as a number of compounds that naturally present in plants. In current years the term phytochemicals which has been used to differentiate plant from the chemicals that do not fulfill the definition of nutrients. Phytochemicals are having nutrient and bioactive compounds present in vegetables, grains, fruits and other food plants. Phytochemicals are generally classified into six major categories. These categories include carbohydrate, lipids, phenolics, terpenoids and alkaloids. Now a days, pest becoming major problem as they are destructive in nature. Rather than using chemicals which are hazardous to environment and to human health, phytochemicals plays very important role to control the population of pest.

Phytochemicals are compounds which are naturally occur in plants. The compounds like phenolics, terpenoids and alkaloids are present in plants which are bioactive in nature. The compounds are extracted from plants and used against pest. These compounds effect on the nervous, digestive and reproductive system of pest and help to reduce the population of pest. Phytochemicals are called as non-nutrient and bioactive plant compounds present in vegetables, fruits and other food compounds which help to reduce the chances of various chronic diseases. Some phytochemicals are energizing the immune system. Some phytochemicals prevent DNA damage and slows the growth of cancer cells.

In an ancient time the use of plant not only for the food, but also to its herbal, cosmetic and agrochemical properties. In the agriculture according to the recent studies, pests are becoming very major problem. It damages our crop as well as its nutritive value. There is a constant search for a natural product from plant which acts as pesticides against various pests. The natural compounds those are present in the plants having biological activities that act against the pests to control their population. These natural products with biological activities minimize the environmental impact of various pesticides used as insecticides. The chemical compounds that are present in plants have these activities and fighting against pests in agriculture (Brito et.al2017).

An approach to the selection of new insecticides that fulfill the requirement of safety and efficacy. Plant extracts have been used by man since the ancient world. In plants there are certain chemical constituents which act against pest. Commercially, there are only few plants including those that contain pyrethin, rotenoids and alkaloids are used as sources of insecticides against pest.( Marangoni et al.,2012). Recent studies shown that plants extracts have that potential which fight against pest. These extracts are non hazardous in nature and having no harmful impact on crops. Rather than this, the plants having certain chemical constituents like phenolic compounds, terpenes and nitrogen compounds these called as phytochemicals and act as insecticides against pest.

The active ingredients are distributed by different plant organs and they are involved in secondary metabolism. The active ingredients in the plants act against the pest and control the population of pest which destroys our crops. Plants have two types of metabolism: primary and secondary metabolism. At first, the primary metabolism which synthesizes the macromolecules proteins, carbohydrates, lipids and nucleic acid. The secondary metabolism is those which produce multiple compounds. (Simoes et al.,2007). With regard to defense against pest, plants have developed two type of defense mechanism. In the direct defense they involved certain substances enzymes, proteins and organs which directly effect the pest. In the indirect defense plant itself emitted certain substances which attract the pest. The certain chemical compounds itself present in the plants having insecticidal properties which effect the pests (Gutierrez and Villegas 2008).

The secondary metabolites exhibit biological activities called as active ingredients which having a therapeutic activities. Secondary metabolites are divided into major three groups: terpenes, phenols, alkaloids and nitrogenous compounds (Taiz and Zeiger, 2013).

Anadenantheramacrocarpa is a genus belongs to the family Fabaceae. The phytochemicals are obtained from the extract of this plant. From the seeds and stem of this plant obtained certain active ingredients which exhibit biological activities. The active compound which is present in the plant is Bufotenin and dimethyl tryptamine which is alkaloid in nature. These active ingredients act against the Spodopterafrugipedra which is called as armyworm. Spodopterafrugipedrais a main pest of maize, rice, cotton, soybean and sorghum (Barros, 2010).

Phytochemicals in the Anadenantheramacrocarpa act on the reproductive system of pest:

Anadenantheramacrocarpa is a plant which belongs to the family Fabaceae. The phytochemicals which present inside the plant called as active ingredients which exhibit certain biological activities. Bufotenin and dimethyl tryptamine act on the reproductive system of pest and causes reduction in larval viability of pest. The phytochemicals Bufotenin and dimethyl tryptamine extracted from seeds and stem of plant. These both compound act against the armyworms which are main pests of maize, rice, cotton and soyabean. (De Moura, 2012).

Malva silvetris is the species of Mallow genus belongs to the family Malvaceae. Malva silvetris having a certain chemical components present inside the plant. These compounds isolated from the leaves and flowers of plant. The chemical components which isolated from the plants called as phytochemicals. The active compounds are Malvin and malonylmalvin these two compounds exhibit biological activities and fight against the major pests of rice.

Phytochemicals present in the Malva silvetris’saction on the digestive system of pests:

Malva silvetris is a plant from which the leaves and flowers of plant, two active compounds Malvin and Malonylmalvin were present in the extract. These both compound act on the digestive system of pests, the pests are unable to feed and reduction in the weight and size of pest which ultimately causes death. (Knaak et al, 2012).

Effect of Malva silvetris act on the reproductive system of pests:

The phytochemicals which are present in the Malva silvetris having certain biological activities. The compounds Malvin and Malonylmalvin act on the reproductive system of pest and causes reduction in the larval viability. (knaak et al, 2012).

The bioactive compounds Malvin and malonylmalvin contain naphtoquinone called as Phytoalaxin. These both compounds are present in the plant. When the extract of Malva silvetris used as insecticide against the pests of rice, the bioactive compounds effects the digestive as well as the reproductive system pests. The botanical extract of Malva silvetris contain the bioactive compounds which used as insecticide and control the population of major pests of rice (Knaak et al, 2012).

Nicotiana tabacum is an annual growing plant. It belongs to the family Solanaceae and in many countries there leaves are to be processed into tobacco. In Nicotiana tabacum certain phytochemicals are present which act as insecticides against the aphids, thrips, leaf hoppers and spider mites. Pyridine alkaloids are present in tobacco as salts and free bases. Nicotine is a bioactive compound that present in the all parts of the plant used as insecticide against pests (Wennig and Robert, 2009).

Effect of Nicotiana tabacum on the nervous system of pests:

Nicotiana tabacum having a phyto-chemical called as Nicotine which acts on the central nervous system of pests. Nicotine binds to nerve receptor and causes uncontrolled nerve firing at neuromuscular junctions in the central nervous system. (Wennig and Robert, 2009).

As the aphids, thrips and mites are the major pests of wheat. The leaf extract of Nicotiana tabacum contains a bioactive compound that act against the major pests of wheat. Nicotine is a photochemical or bioactive compound which is present in all parts of plant. Nicotine contains Nornicotine and anatabine which effects the nervous system of pest. When extract of plant sprayed on the aphids, thrips and mites it act as an insecticides and control the population of pest (Atif et al., 2013).

Rotenone is called as Phytochemical which is isolated from the plant Lonchocarpus. The plant genus belongs to the family Fabaceae. Rotenone is an colorless, crystalline and odorless compound which used as insecticide which fights against the pests. It is isolated from the seeds, roots and stems of Lonchocarpus plant. Rotenone work as poison (R.T Gahukar, 2010).

Phytochemicals present in the Lonchocarpus act on the respiration system:

Rotenone is a phytochemical which act on the respiratory system of pests. Rotenone blocks the respiration by electron transport chain on complex to ubiquinone and it ultimately causes death. Caterpillars are major pests of maize, sorghum, wheat and rice. It effects our crops and causes damage. As the farmers usually used chemical insecticides against the pests, but the main cause of chemicals that are not easily biodegradable and toxic to non target organisms. Rather than chemicals, according to the recent studies in the field of agriculture the bioactive compounds which are present in the plants called as phytochemicals used as insecticides which are non hazardous in nature. Rotenone is a Phytochemical which interfere with the electron transport chain. It inhibits the transfer of electron from iron-sulfur centers in complex 1 to ubiquinone. Complex 1 is unable to pass off its electron to CoQ, creating a back up of electrons with in mitochondrial matrix and causes death of pests (Lisa minter, 2014).

Ryaniaspeciosa is a species which belongs to the family Salicaceae. Woody stems of this plant contain alkaloids with insecticidal activity. The bioactive compound which is present in the Ryania collectively called as ryanoids. The most active ryanoids is ryanodine and 9, 21-dehydro-ryanodine (Khater, 2012).

Phytochemicals present in the Ryaniaspeciosa effects the muscles of pests:

Ryaniaspeciosa is a plant from which a phytochemicals Ryanodine and 9,21 dehydro-ryanodine the most active alkaloids. It effects the muscles by binding to the calcium channels in the sarcoplasmic reticulum, it causes influx of calcium ions into cells and which ultimately causes death.

Aphids, mites and caterpillars are the major pests of wheat, rice and maize. The bioactive compound which is present in the Ryaniaspeciosa called as ryanoids. The most active ryanoids are ryanodine and 9, 21-dehydro-ryanodine which is alkaloid in nature. It effects the muscles by binding to the calcium channels; it causes influx of calcium ions and causes death of pests. It has a longer residual activity than most other botanical insecticides. As the compounds are isolated from the plant that’s why it is non hazardous to environment and less toxic to non target species.

So many reports are available which explain about the effectiveness of phytochemicals which are present in the plants. The plants contain certain bioactive compounds which are having efficiency to kill the pests. The phytochemicals can compete with chemical insecticides. As the chemical insecticides are not easily biodegradable and harmful to non target species, but the phytochemicals are easily biodegradable and non toxic to non target species.

CONCLUSION:

The phytochemicals used as insecticides which are eco-friendly, easily biodegradable and non toxic to non target species. The potential of phytochemicals that they have efficiency to kill the pests. The botanical insecticides having certain bioactive compounds which act against the major pests of wheat, rice, maize and soyabean. These active compounds act on the system of the pests and can kill the pests. The main aims of this review that to illustrate about the effectiveness of phytochemicals. Considering ever increasing cost farm inputs or chemical insecticides, reduction in production costs and increase in productivity are the current challenges. Integrated pest management is found to be economical and against several pests and also appreciated by farmers. Generally, the phytochemicals which are present in the botanical insecticides do not persist in the environment and they are quickly degraded by various environment factors such as temperature, rainfall and ultraviolet rays. Some insecticides are insect growth regulators which only effective against the immature stages of pests, phytochemicals having repellent effects and due to this effect insect feeding may be reduced. At present only a few numbers of botanical insecticides are available for farmers in the market. Large scale production of botanical insecticides are very costly for farmers which is not currently feasible for most commercial products, but it is likely that major breakthroughs in botanical pesticide technology to control the pests.

CONFLICT OF INTERESTS:

The authors affirm no conflicts of interests with respect to the authorship and/ or publication of this article.

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Received on 27.03.2019 Modified on 26.04.2019

Research J. Pharm. and Tech. 2019; 12(9):4595-4598.

DOI: 10.5958/0974-360X.2019.00790.X