Botanical pesticides for sustainable agriculture
By Faizan Wazir and Asia Nosheen
PLANTS ARE considered as natural laboratories in which a great number of chemicals are biosynthesized. These diverse groups of chemicals protect plants from attack of pathogens and predators. By studying the diverse chemistries of many different plant species, scientists have discovered many useful compounds that can be used as bio-pesticides.
Plant extracts have been used as biological pesticides for many decades. The first botanical insecticide dates back to the 17th century, when it was shown that nicotine from tobacco leaves killed plum beetles. With the discovery and commercial scale production of synthetic pesticides, the use of bio-pesticides was drastically reduced in the 19th century. The major reason was that synthetic pesticides were more effective, fast in action and easily available. However, the toxicity and negative environmental effects associated with most of the synthetic pesticides diverted the attention of scientists towards the usage of plant secondary metabolites to control plant pathogens. Currently a lot of plant based biopesticides have been investigated and commercialized.
Botanical pesticides are generally regarded as environmentally safe and they can be used directly in organic agriculture practices. Moreover, plant extracts contain multiple active ingredients that can be extended to a range of pests. They are often effective in very small amounts and decompose quickly thereby resulting in lower exposures and do not cause pollution problems.
Pakistan is an agriculture country and consumes a lot of pesticides to boost up its agriculture production. According to a survey report published in Pakistan Economic and Social Review, the total outlay of farmers on the purchase of pesticide in Pakistan was estimated at Rs. 19.612 billion against import bill of Rs. 8.138 billion for 2003. Total sale amount of insecticides in Sanghar, Nawabshah, and Naushahro Feroze districts was estimated to be Rs. 471.73 million in 2003-04.
Agro-climatic conditions of Pakistan support the growth of a vast majority of plant species which extracts can be utilized as sources of bio-pesticides. The most common plants having potential to be used as a source of bio-pesticides include Neem (Azadirachta indica), Sweet flag (Acorus calamus), Clove (Syzygium aromaticum), Delphinium (Delphinium denudatum), Walnut, Keekar (Acaccia nilotica), Aak (Calotropis procera) and Safaiyda (Eucalyptus camaldulensis) etc. One such plant based bio-pesticide has been prepared by the International Centre for Chemical and Biological Sciences (ICCBS), University of Karachi (KU) and has been marketed.
The interest of people in organic farming is increasing throughout the country and area under organic farming is increasing rapidly. This indicates that there is a huge scope for the growth of botanical pesticides in the country. If an effort is made towards production of plant based bio-pesticides on commercial scales, this can be an economically viable option for employment generation in the rural areas.
Moreover, widespread plantation of pesticides producing plant species and proper conservation practices will make the commercialization of these environment friendly pesticides easier and attractive for the investors. Support to research institutes for continuous research in this field and public awareness about the advantages and use of botanical pesticides will further help in making botanical pesticides as more attractive for both producers and consumers. University-industry linkages will boost up the effectiveness and sustainability of these pesticides.