Biopesticide for Sustainable Agriculture
Imran Khan, Muhammad Umer, M. Umair Hassan and M. Mehran Aslam
Agriculture is facing the threat of insect and disease since from the beginning of agriculture history. In the beginning man lives in cave and use wild plants for food and leaves for clothes. Human start living together and civilization start. They collect the seed and start practical agriculture. Insect and disease are causing a lot of damage from the beginning of the agriculture. Many famines in history occur because of disease e.g. Irish famine due to potato disease caused by fungus. Until mid-1900 certain inorganic chemicals and plant originated chemicals are used to control insect and diseases. After green evolution (1960) dramatically increase in the production of yield due to development of fertilizers. But the chances of disease also increase. To control these diseases and to obtain maximum yield extensive use of pesticide and fertilizers disturb our natural soil climate. In advanced agriculture age 10-50% food is loss due to insects and diseases.
In November 2015 more than 100 countries gathered in France. It was conference on climate change and environmental pollution. The main agenda of the conference was how to mitigate the current challenges. Pakistan placed 12 position affected by climate change and pollution. Sustainable agriculture is the system of farming in which maximum production is obtained from existing resources. Now a day’s world is focusing on biopesticides. These environmental friendly, ease to use and naturally originated. Their persistant time is very short and less toxic then pesticides.
Biopesticides are substance having pesticidal properties which are originates/ obtained from natural resources. These natural resources may be plants, animals, virus, bacteria or minerals. These natural substances provide protection against soil born disease and insect-pests. Biopesticides are the key component in integrated pest management (IPM). Plants have produced resistant against diseases in coordination of it. Biopesticides used in agriculture have four sources (microbial, botanical, biochemical and RNAi pesticides). In microbial biopesticides bactria, viruses, fungi and nematods origin biopesticides.
Among the bioagents bacteria are most potent because of its toxic protein crystal. B. turigenensis is spore forming bacteria produces toxin that disturb insect digestive system and cause death of the insect. Toxic protein is effective against insect if eaten at alkaline PH and specific temperature. Viruses are insect specific and their efficiency is different in different environment. These are affective against catterpiller insects. When it reach the (gut) digestive system of insect and replicate their and clog it. It disturbs the matting, feeding and movement of insect. Insect physiology is reduced. Death of insect can occur within 3 to 8 days after infection.
More than 700 species of fungi have insecticidal properties. Most of the fungi belong to zygomycota family and their host range is different for different fungi. Fungi can control due to enzymatic properties. It attack on insect body and penetrates its hyphae in insect cuticle. Certain types of extra and intra cellular enzymes can cause the breakdown of insect body. Sometime fungi produce spore in insect body and after their death these spore spread through wind or water. Nematodes form beneficial relationship with bacteria. Bacteria cause the death of insect while it obtained their food from dead insect. Nematodes require specific condition for pathogenicity. They can perform better narrow temperature and moisture range.
Botanical biopesticides / plant incorporated protectant are certain compounds are extracted from plants. These are used in crop protection. These compounds can be used as insect repellent because of its odor. Tobacco, neem and acacia plant extractant are used.
Allellochemical are produced by plants roots in soil that suppress the growth of other plants and weeds. To reduce the competition among plants and insects for light, food and for space allellochemical are produced. These may be certain hormone or metabolites that support the plant growth. Sex pheromones are certain type of chemical that interferes with the mating process of insects. Insect cannot increase his generation.
RNAi pesticides are new type of pesticides in which single stand of RNA is used. It is fragile and easily decomposable and persistent time in soil is very short. It is applied as spray on plants. It does not change the genetic makeup of the plants.
There are certain problems with the promotion of biopesticides:
- Lack of laboratory for quality control.
- Lack of credit/ poor economy of the country.
- Lack of technical labour and extention work.
Sustainable agriculture is the only solution to control climate change and environmental pollution. If good agricultural practices are used then soil health will be good. When soil is healthy our crops will be healthy.