Microbial Control of Pests and Weeds PDF

AKSHATHA BANADKA’S CLASS -ABC Microbial control of pests and weeds BY Dr. AKSHATHA BANADKA AKSHATHA BANADKA’S CLASS -ABC In the next two decades, crop production must increase sustainably withou...

AKSHATHA BANADKA’S CLASS -ABC Microbial control of pests and weeds BY Dr. AKSHATHA BANADKA AKSHATHA BANADKA’S CLASS -ABC In the next two decades, crop production must increase sustainably without relying on synthetic chemical pesticides due to their declining accessibility and resistance issues. Managing pests and weeds in agriculture without relying on synthetic chemical pesticides is crucial for sustainable food production. The pest and weed management can be achieved via : 1. Redesigning Cropping Systems: crop rotation and intercropping. 2. Diversifying Biocontrol Strategies: natural enemies of pests, such as beneficial insects, parasitoids, and predators. 3. Plant Breeding Strategies: Breed crops for resistance to pests and diseases. 4. Agricultural Machinery and Digital Technologies: Use sensors, drones, and data analytics to monitor crop health and detect early signs of pests or AKSHATHA BANADKA’S CLASS -ABC BIOLOGICAL CONTROL OF PESTS AND WEEDS OF AGRICULTURAL CROPS Biological control is a process of suppressing or controlling the unwanted population of insects, other animals, or plants by the introduction or artificial increase of their natural enemies Biological Control of Pests: Integrated pest management (IPM) emphasizes eco-friendly alternatives to chemical insecticides. Microbiological pathogens (bacteria, fungi, viruses, protozoans) play a crucial role. AKSHATHA BANADKA’S CLASS -ABC BIOLOGICAL CONTROL OF PESTS AND WEEDS OF AGRICULTURAL CROPS The pests and weeds can be controlled using: Bioinsecticides Bioherbicides Bioinsecticides Bioherbicides AKSHATHA BANADKA’S CLASS -ABC Microbial bioinsecticide Microbiological pesticides use microorganisms (fungi, bacteria, viruses, protozoans) as active components. Each active constituent is specific to its target insect pest. AKSHATHA BANADKA’S CLASS -ABC AKSHATHA BANADKA’S CLASS -ABC Bacterial bioinsecticide Bacterial biopesticides use microorganisms (e.g. Bacillus, Clostridium, Pseudomonas) as insecticides. B. thuringiensis (Bt) is widely used against over 150 insect species. Bt produces a toxin that binds to larval stomach cells, leading to insect larval death. Recombinant DNA technology has enabled the transfer of Bt genes to crop plants like tomato and AKSHATHA BANADKA’S CLASS -ABC Mechanism of Toxicity by B. thuringiensis 1.Ingestion and Activation 2.Proteolytic Activation 3.Binding to Midgut Receptors 4.Pore Formation 5.Cellular Effects 6.Systemic Effects AKSHATHA BANADKA’S CLASS -ABC Bacterial bioinsecticide AKSHATHA BANADKA’S CLASS -ABC Fungal bioinsecticide Entomopathogenic fungal species play a vital role as biocontrol agents against insects. Approximately 90 genera and over 700 species are considered insect-infecting fungi. Entomopathogenic fungi attack and infect insect hosts through integument or ingestion. Some fungi do not require ingestion; physical contact is sufficient. Soil fungus Beauveria bassiana effectively controls various pests. Genus Trichoderma manages plant diseases by parasitizing harmful fungi in the root zone. AKSHATHA BANADKA’S CLASS -ABC Beauveria bassiana mode of action Infection Process of Beauveria bassiana spores: Contact with Insect Cuticle Enzyme Production Spore Germination Penetration into Hemolymph Formation of Blastospores Colonization and Toxin Production Insect Death AKSHATHA BANADKA’S CLASS -ABC Fungal bioinsecticide Rhinoceros beetle Spittlebugs Potato beetle Soybean caterpillar AKSHATHA BANADKA’S CLASS -ABC Viral bioinsecticide Viruses have been isolated from over 1000 insect species across at least 13 different insect orders. Baculoviruses are the major group of arthropod viruses well known due to their potential as agents of biological control of pests in agriculture and forestry. Baculoviruses are double-stranded DNA viruses that infect insects through ingestion. The family Baculoviridae comprises two genera: the Nucleopolyhedrovirus (NPVs) and the Granulovirus (GVs) Once ingested, they enter the insect’s body and cause infection of the gut cells. Within a few days, the infected insect stops feeding and eventually dies, releasing virus particles into the environment Baculoviruses are considered safe for vertebrates. Baculoviruses (family Baculoviridae) are a significant focus for commercial viral biopesticide development. AKSHATHA BANADKA’S CLASS -ABC Mechanism of Toxicity by Baculovirus Ingestion Dissolution in the Gut Infection of Midgut Cells Virus Entry into Cells Replication and Spread Systemic Infection Death of the Host Environmental Release AKSHATHA BANADKA’S CLASS -ABC Viral bioinsecticide Tiger moth Rice leafroller Cotton bollworm AKSHATHA BANADKA’S CLASS -ABC AKSHATHA BANADKA’S CLASS -ABC Biological Control of Weeds Bacteria fungi and viruses have been used for weed management. Bioherbicides are gaining acceptance due to cost- effectiveness. Consumers prefer crops grown with bioherbicides over synthetic chemical herbicides. AKSHATHA BANADKA’S CLASS -ABC Bacterial Bioherbicides Bacteria offer advantages over other bioherbicides. They multiply rapidly, possess genetic flexibility, and require simple nutrients. Genera like Pseudomonas and Xanthomonas are promising. Specific strains suppress weed growth (e.g., Pseudomonas fluorescens D7, Xanthomonas campestris). Bacterial metabolites disrupt plant germination and growth. Pseudomonas fluorescens Strain Xanthomonas campestris pv. poae Strain WH6 (JT-P482) Activity: Inhibits Activity: Controls annual germination of multiple plant bluegrass (Poa annua) species without affecting other Mechanism: Produces turf species. Germination Arrest Factor Mechanism: It involves (GAF), identified as 4- colonization of the host formylaminooxy-L- plant's xylem, spreading vinylglycine. through the plant and the GAF interferes with enzymes phytotoxic metabolites utilizing AKSHATHA pyridoxal BANADKA’S CLASS -ABC produced by it interacts AKSHATHA BANADKA’S CLASS -ABC Bacterial Bioherbicides AKSHATHA BANADKA’S CLASS -ABC Fungal Bioherbicides: Fungi are used as biocontrol agents for weed management. Colletotrichum species are used as commercial formulations for weed control. Examples include Colletotrichum. gloeosporioides f. sp. malvae (against Malva pusilla) and C. gloeosporioides f. sp. aeschynomene (against Aeschynomene virginica). Sclerotinia minor is useful in turf weed control. Mechanism of action involves acid production that disrupts cell walls and suppresses weed defence. AKSHATHA BANADKA’S CLASS -ABC Fungal Bioherbicides mode of action Spore Germination on Weed Plants Penetration of Plant Defenses by Fungal Hyphae Internal Colonization by Fungal Mycelium Pathogenesis and Disease Symptom Formation Nutrient Competition and Resource Depletion Reproduction and Spore Spread AKSHATHA BANADKA’S CLASS -ABC Fungal Bioherbicides:  Viral bioherbicide Viruses are used as bioherbicides to manage agricultural crop weeds. Tobacco mild green mosaic virus can control Solanum vivarium growth and activities. Araujo mosaic virus effectively controls Araujo moratorium (reported by Elliot et al. ). Tobacco rattle virus is being considered for controlling Impatiens glandulifera. These viral bioherbicides significantly reduce weed populations, which compete with crops. The use of viral bioherbicides helps prevent crop losses and increases the yield and quality of agricultural produce. AKSHATHA BANADKA’S CLASS -ABC Tobacco mosaic virus (TMV; Tobamovirus, Virgaviridae) is a rodlike virus with a length of 300 nm and diameter of 18 nm. TMV capsids are composed of 2130 identical protein subunits, which assemble around the viral ssRNA to form a helical structure, with a hollow central cavity of 4 nm diameter. Mechanism of Toxicity by Tobacco mild green mosaic virus 1. Entry 2. Initial Infection 3. Movement Protein 4. Replication 5. Cell-to-Cell Movement 6. Systemic Infection AKSHATHA BANADKA’S CLASS -ABC Viral bioherbicide AKSHATHA BANADKA’S CLASS -ABC Global Biopesticide Market Overview There are about 1400 biopesticide products produced globally, making up just 2.5% of the total pesticide market. The market for biopesticides and bioherbicides needs significant growth to reduce reliance on synthetic chemicals. Global use of biopesticides and bioherbicides is growing by nearly 10% annually, but further market expansion is necessary to significantly AKSHATHA BANADKA’S CLASS -ABC Importance of Research, Collaboration, and Future Development The development of the biopesticide and bioherbicide market relies heavily on research and collaboration between enterprises and research institutes. There is a need for more comprehensive and systematic research reports on biological control agents. Biopesticides and bioherbicides currently cannot fully replace chemical pesticides and herbicides, so a coexistence strategy in agriculture and forestry is beneficial. Accelerating the practical application of research results is key to large-scale industrial development of biopesticides and bioherbicides. AKSHATHA BANADKA’S CLASS -ABC References Verma, D., Banjo, T., Chawan, M., Teli, N., & Gavankar, R. (2020). Microbial Control of Pests and Weeds. Natural Remedies for Pest, Disease and Weed Control, 119–126. doi:10.1016/b978-0- 12-819304-4.00010-5 THANK YOU