Unit -1
Biopesticide and Biofertlizers
Definition:
Biopesticides are substances derived from natural materials such as animals, plants, bacteria, and certain minerals, which are used for controlling pests, including insects, weeds, and pathogens, while minimizing harm to humans, non-target organisms, and the environment. They encompass a diverse array of pest management tools, including microbial pesticides, plant-incorporated protectants, and biochemical pesticides.
History and Concept of Biopesticides:
The concept of using biological agents for pest control dates back centuries, with early examples including the use of predators such as ladybugs to control aphids and the application of microbial agents like Bacillus thuringiensis (Bt) to manage insect pests. However, modern biopesticides have evolved significantly, with advances in biotechnology, microbiology, and ecological understanding enabling the development of more targeted and effective formulations.
Importance, Scope, and Potential of Biopesticides:
1. Environmental Sustainability: Biopesticides offer environmentally friendly alternatives to conventional chemical pesticides, reducing the negative impacts on ecosystems, water quality, and non-target organisms.
2. Human and Animal Safety: Biopesticides generally have lower toxicity to humans and animals compared to synthetic chemicals, minimizing health risks associated with pesticide exposure.
3. Resistance Management: Biopesticides provide additional tools for integrated pest management (IPM) strategies, helping to mitigate the development of resistance in pest populations.
4. Market Opportunities: With growing consumer demand for organic and sustainable agricultural products, there is increasing market potential for biopesticides as safer and more eco-friendly pest control options.
5. Regulatory Support: Many governments worldwide are encouraging the use of biopesticides through regulatory incentives and support for research and development in this field.
Definitions, Concepts, and Classification of Biopesticides:
1. Pathogen-based Biopesticides: These biopesticides consist of living microorganisms such as bacteria, fungi, viruses, or protozoa that infect and kill pests. Examples include Bacillus thuringiensis (Bt), which produces toxins lethal to certain insect larvae, and entomopathogenic fungi like Beauveria bassiana, which infect and kill insects.
2. Botanical Pesticides: Derived from plants, botanical pesticides contain natural compounds with pesticidal properties. Examples include pyrethrum, derived from chrysanthemum flowers, and neem oil, extracted from the neem tree seeds. These substances often act as repellents, feeding deterrents, or growth regulators against pests.
3. Biochemical Pesticides: These biopesticides contain naturally occurring substances such as pheromones, insect hormones, or enzymes that disrupt pest behavior, development, or physiology. They typically have low toxicity to non-target organisms and degrade rapidly in the environment.
4. Biorationales: Biorationales refer to the principles underlying the use of biopesticides, emphasizing ecological sustainability, compatibility with IPM strategies, and minimal environmental impact. They encompass concepts such as host specificity, natural enemy conservation, and non-target organism safety.
Botanicals and Their Uses:
Botanical pesticides are derived from plants and their extracts, which contain compounds with pesticidal properties. Common botanical pesticides include:
- Pyrethrum: Extracted from chrysanthemum flowers, pyrethrum contains pyrethrins, natural insecticidal compounds effective against a broad range of pests.
- Neem Oil: Derived from the seeds of the neem tree (Azadirachta indica), neem oil contains azadirachtin and other compounds that repel insects, disrupt their growth and development, and inhibit feeding and egg-laying.
- Rotenone: Obtained from the roots of certain tropical plants, rotenone acts as a broad-spectrum insecticide and piscicide, targeting a wide range of insect pests and fish species.
Virulence, Pathogenicity, and Symptoms of Entomopathogenic Pathogens and Nematodes:
Entomopathogenic pathogens and nematodes are organisms that infect and kill insect pests, contributing to biopesticide formulations. Key terms related to these biocontrol agents include:
- Virulence: The ability of a pathogen or nematode to cause disease or mortality in a host insect. Virulence often varies among strains and species, influenced by factors such as environmental conditions and host susceptibility.
- Pathogenicity: The capacity of a pathogen or nematode to cause pathology or disease symptoms in its host. Pathogenicity involves various mechanisms, including the production of toxins, enzymes, or reproductive structures that disrupt host physiology and tissue integrity.
- Symptoms: Signs of infection or disease observed in insect hosts following exposure to entomopathogenic pathogens or nematodes. These symptoms may include changes in behavior, morphology, or physiology, such as lethargy, discoloration, tissue necrosis, or the presence of characteristic reproductive structures (e.g., fungal spores or nematode eggs) on or within the host's body.
