Authors: Bipasa Sarkar, Irani Mukherjee and Aman Kumar
Division of Agricultural Chemicals, ICAR-Indian Agricultural Research Institute, New Delhi 110012, India.
E mail: bipasasarkar@yahoo.co.in
Background
The term ‘’crop protection agents’’ represents a wide class of compounds, including fungicides, insecticides, herbicides, nematicides, rodenticides, molluscicides and plant growth regulators (Sarkar and Roy, 2013). In recent years, the use of crop protection agents around the world has impacted the environment negatively, led to pest resurgence and resistance to pesticides. They have lethal effects to non-target organisms in the agro-ecosystems in addition to direct toxicity to users. Therefore, it is imperative to search for safer alternative means of pest control, which can minimize the use of synthetic pesticides. The important alternatives are botanical pesticides which may minimize the use of chemical pesticides because they possess an array of activities (Prakash et al. 2008).
It is known that some plants protect themselves better than others due to presence of some pesticide acitivities and humans used these plants parts as pesticides, popularly known as botanical pesticides. They are mentioned in Hieroglyph, Chinese, Greek, and Roman antiquity and also in India where the use of the neem tree (Azadirachta indica Juss.; Meliaceae) was reported in the Veda, a body of manuscripts written in archaic Sanskrit dated at least 4,000 years ago (Philogène et al. 2005). It is thus difficult to assess exactly where and when plants or plant extracts were systematically used in plant protection or, more generally, in agriculture. During 18th century, some publications dealt with plant-based formulations to control insect pests (Shepard 1951). At the end of the 19th century, methods including the use of toxic plants or minerals, oils, tars, sulfocalcic sprays, boiling water, and so forth, were commonly put into practice (Whittaker and Feeny 1971). Integration of empirical and scientific observations led to the development of plant extracts (El-Wakeil 2013). Therefore, major plant parts /extracts used in crop protection are given below.
Nicotine
Nicotine is extracted mainly from tobacco (Nicotiana spp.) plants that have been used for centuries to kill sucking insects such as aphids, thrips and spider mites. The extract is highly toxic to every living things, including humans, animals and insects. Nicotine sulfate is considered to be a botanical pesticide, used in organic cultivation. However, due to its toxicity to some useful organisms, a family of synthetic chemicals that mimic the effects of nicotine on insect nervous systems feature in many insecticides has been developed which is known as neonicotinoid group of insecticides .
Karanjin
Karanja oil is extracted from seeds of Karanja Tree (Pongamia glabra) which is widely found in India. It is used in agriculture and pharmacy due to its insecticidal and acaricidal properties which acts against a number of pests and insects. Karanjin is the main active ingredient of Karanja oil that has nitrification inhibitory properties.
Rotenone
Rotenone is an odourless, colourless, crystalline ketonic chemical compound used as broad-spectrum insecticide and pesticide. It occurs naturally in the seeds and stems of the Jicama vine plant (Pachyrhizus erosus); and the roots of several other members of Fabaceae family.
Neem
Dried neem (Azadirachta indica) leaves are traditionally used as botanical pesticides for several decades in India. Dried neem leaves are placed in cupboards to prevent insects eating the clothes. The major ingredients are azadirachtin and nimbidin. Neem seeds are ground into a powder that is soaked overnight in water and sprayed onto the crop, providing a natural alternative to chemical pesticides. Neem does not directly kill insects on the crop rather, it acts as an anti-feedant, repellent, and egg-laying deterrent, protecting the crop from damage. The insects starve and die within a few days. Neem also suppresses the hatching of pests as well as insects. Neem cake is often sold as a fertilizer. It acts as vermifuge, insecticide, astringent, tonic and antiseptic. It possess anti-diabetic, anti-bacterial, anti-viral properties and used successfully in cases of stomach, worms and ulcers. It used as pesticides and could be applied to protect stored seeds against insects. Young fried neem leaves act as an appetizer.
Limonene
Limonene or d-Limonene is also used as botanical insecticide; the d- enantiomer is most active as an insecticide. The main source is the skin of citrus fruit (Citrus spp.). It is used as a cleaning agents such as hand cleansers to give a lemon orange fragrance and because of its ability to dissolve oils. Therefore, it is used as insect repellent in many households.
Pyrethrins
Pyrethrum is an another important botanical pesticides derived from the dried flower of chrysanthumem cinerariifolium, that have potent insecticidal activity by targeting the nervous systems of insects. It is also used as lice remedy in the Middle East. They are biodegradable compounds. Pyrethrins are considered to be low toxic pesticides from a human health standpoint. It is one of the most commonly used non-synthetic insecticides allowed in certified organic agriculture.
References:
- El-Wakeil NE (2013) Botanical Pesticides and Their Mode of Action Gesunde Pflanzen 65:125–149
- Philogène BJR, Regnault-Roger C, Vincent C (2005) Botanicals: yesteday’s and today’s promises. In: Regnault-Roger C, Philogène BJR, Vincent C (eds) Biopesticides of plant origin. Lavoisier and Andover, UK, pp 1–15
- Prakash A, Jagadiswari Rao and V. Nandagopal (2008) Future of Botanical Pesticides in rice, wheat, pulses and vegetables pest management. Journal of Biopesticides, 1(2):154 – 169.
- Sarkar B, Roy A (2013) Synthesis, characterization, biocidal activity and phytototoxic effect OF Mn (II), Fe (II), Co (II), Cu (II), Zn (II) Complexes OF 3, 5-DINITRO Benzoic acid. International J of analytical Phamaceutical and Biomedical Science 2 (4), 1-7
- Shepard H (1951) The chemistry and action of insecticides. McGraw- Hill, New York, p 504
- Whittaker RH, Feeny P (1971) Allelochemicals: chemical interactions between species. Science 171:757–770
About Author / Additional Info:
I am working as a Research Associate in the Division of Agricultural Chemicals, ICAR-Indian Agricultural Research Institute, New-Delhi-110012