- Biological pesticide
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The term biological pesticide or biopesticide is used for microbial biological pest control agents that are applied in a similar manner to chemical pesticides. Commonly these are bacterial, but there are also examples of control agents based on fungi, viruses and nematodes. Weeds and rodents have also been controlled with microbial agents.BT-cotton is best example in India(Farhan,2011,AEBM)
One well-known insecticide example is Bacillus thuringiensis, a bacterial disease of Lepidoptera, Coleoptera and Diptera. Because it has little effect on other organisms, it is considered more environmentally friendly than synthetic pesticides. The toxin from Bacillus thuringiensis (Bt toxin) has been incorporated directly into plants through the use of genetic engineering.
Other microbial control agents include products based on:- entomopathogenic fungi (e.g.Beauveria bassiana, Lecanicillium spp., Metarhizium spp.),
- plant disease control agents: include Trichoderma spp. and Ampelomyces quisqualis (a hyper-parasite of grape powdery mildew); Bacillus subtilis is also used to control plant pathogens.
- beneficial nematodes attacking insect (e.g. Steinernema feltiae) or slug (e.g. Phasmarhabditis hermaphrodita) pests
- entomopathogenic viruses (e.g.. Cydia pomonella granulovirus).
Biopesticides, key components of integrated pest management (IPM) programmes, are receiving much practical attention as a means to reduce the load of synthetic chemical products being used to control plant diseases. In most cropping systems, biological pesticides should not necessarily be viewed as wholesale replacements for chemical control of plant pests and diseases, but rather as a growing category of efficacious supplements that can be used as rotation agents to retard the onset of resistance to chemical pesticides and improve sustainability. In organic cropping systems, biopesticides can represent valuable tools that further supplement the rich collection of cultural practices that ensure against crop loss to diseases.
Biopesticides for use against crop diseases have already established themselves on a variety of crops. For example, biopesticides already play an important role in controlling downy mildew diseases. Their benefits include: a 0-Day Pre-Harvest Interval (see: maximum residue limit), the ability to use under moderate to severe disease pressure, and the ability to use as a tank mix or in a rotational program with other registered fungicides. Because some market studies estimate that as much as 20% of global fungicide sales are directed at downy mildew diseases, the integration of biofungicides into grape production has substantial benefits in terms of extending the useful life of other fungicides, especially those in the reduced-risk category.
A major growth area for biopesticides is in the area of seed treatments and soil amendments. Fungicidal and biofungicidal seed treatments are used to control soil borne fungal pathogens that cause seed rots, damping-off, root rot and seedling blights. They can also be used to control internal seed–borne fungal pathogens as well as fungal pathogens that are on the surface of the seed. Many biofungicidal products also show capacities to stimulate plant host defenses and other physiological processes that can make treated crops more resistant to a variety of biotic and abiotic stresses.
The Manual of Biocontrol Agents[1] gives a review of the available biological insecticide (and other biology-based control) products. In order to implement these environmentally-friendly pest control agents, it is often especially important to pay attention to their formulation[2] and application.[3]
Perceived advantages
- do not leave harmful residues
- substantially reduced impact on non-target species
- when locally produced, may be cheaper than chemical pesticides
- in the long-term may be more effective than chemical pesticides (e.g. as demonstrated by the LUBILOSA Programme)
Perceived disadvantages
- high specificity, which will require an exact identification of the pest/pathogen and may require multiple pesticides to be used
- often slow speed of action (thus making them unsuitable if a pest outbreak is an immediate threat to a crop)
- often variable efficacy due to the influences of various biotic and abiotic factors (since biopesticides are usually living organisms, which bring about pest/pathogen control by multiplying within the target insect pest/pathogen)
- living organisms evolve and increase their resistance to biological, chemical, physical or any other form of control. Unless the target population is completely exterminated or is rendered incapable of reproduction, the surviving population will inevitably acquire a tolerance of whatever pressures are brought to bear - this results in an evolutionary arms race.
See also
- biopesticide
- biological pest control
- Integrated Pest Management
- LUBILOSA
- plant and fungal extracts
References
- ^ Copping L.G. (ed.) (2009). The Manual of Biocontrol Agents (formerly the Biopesticide Manual) 4th Edition. British Crop Production Council (BCPC), Farnham, Surrey UK; 851 pp.
- ^ Burges, H.D. (ed.) 1998 Formulation of Microbial Biopesticides, beneficial microorganisms, nematodes and seed treatments Publ. Kluwer Academic, Dordrecht, 412 pp.
- ^ Lacey & H. Kaya (eds.) (2000) Field Manual of Techniques for the Evaluation of Entomopathogens Kluwer Academic, Dordrecht, NL, 911 pp.
External links
- [1] US Environmental Protection Agency (EPA).
- [2] Biopesticide Industry Alliance (BPIA)
- [3] International Biocontrol Manufacturers' Association (IBMA)
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