ENT 605 Microbial pesticide.pptx entomopathogenic insects

Biopesticide and its types

1. Microbial Control ENT- 605

2. Biochemical Pesticides Biochemical pesticides are plant-derived compounds that use non-toxic ways to control pests.  On the contrary, traditional insecticides often consist of synthetic substances that directly kill or inactivate the bug. For instance, this pesticide comprises insect sex pheromones, which prevent mating, and various other scented plant extracts, such as phytochemicals that attract insect pests and function as toxicants, insect growth regulators, repellents, and antifeedants.

3. These pesticides affect an insect’s physiology, metabolic pathway, or neurological system through ingestion, inhalation, or absorption by the insect’s cuticle. Restricting spiracles inhibits insect breathing, which causes asphyxia. It will disrupt the insect membrane’s ion channel and ion pump, disrupting signal transduction at the cellular level. Monoterpenes is an essential oil that works as a neurotoxin by interfering with the acetylcholinesterase enzyme, vital in transmitting nerve impulses in insects, resulting in their paralysis and eventual demise.  Additionally, it prevents the synthesis of DNA, RNA, and proteins.

4. Plant-Incorporated Protectants Plant-incorporated protectants, genetically modified plants, or manipulated plants have the toxin-producing genes to combat the pest. For instance, the Bt gene is transferred in the cotton plant. The target gene is transferred into transgenic plants using Agrobacterium-mediated transfer, gene guns, or ballistic techniques. The above methods were applied to rice, corn, wheat, and maize.  Additionally, the plant-incorporated protections may pose some hazards, including those to non-target pests, human health, the environment, the spread of the PIP gene to other plants, and the appearance of herbicide- or insect-resistant organisms.

5. Continued.. The majority of broad-spectrum, pest-specific biopesticides fall into the microbial category. Microbial pesticides use microorganisms such as bacteria, viruses, fungi, and protozoans as biological components.  These types of species are precisely delivered to the target species.  Microbial biopesticides are environment-friendly, host-specific, and self-replicating. Bt ( B. thuringiensis ) is one of the most commonly employed bacteria to combat insect pests to control insect pests. 

6. Lepidopterans, coleopterans, and dipterans are just a few of the many problems that it is used to fight off.  The most prevalent commercially available bacterial species as bio-pesticides are  Bacillus popilliae , B. thuringiensis, Clostridium bifermentans , Pseudomonas alcaligenes, Pseudomonas aureofaciens , Saccharopolyspora spinosa, Serratia entomophila ,  and  Streptomyces avermitilis ; as for fungi-based pesticides,  Beauveria bassiana , Metarhizium anisopliae, Nomuraea rileyi , Trichoderma viride , Paecilomyces farinosus ,  and  Verticillium lecanii . The use of baculoviruses (BV) as viral biopesticides is every day. 

7. Disadvantages of Biopesticides Biopesticides are photodecomposed by ultraviolet light, radiation, and heat and must be used only in the morning. Only a specific species or group of insects are poisoned by microbial insecticides; the others may still exist and inflict damage. Some of the fungal pesticides are expensive.

8. Some of the fungal pesticides are expensive. Possibly having a shorter life span than synthetic pesticides, biopesticides are less practical to store and utilize. Biopesticides may need specialized tools or application methods, making them more challenging to apply .

9. Mode of action of  B thuringiensis B.thuringiensis  can be used as a source of poisonous genes that, when expressed in plants, provide toxic particles harmful to several insect pests. The steps involved are:   Insects ingest endotoxin produced by bacteria during spore formation in leaves ( B. thuringiensis ) The alkaline (pH 9–12) midgut environment in insects such as Lepidopterans causes the crystals to dissolve. The solubilization of protein crystals releases and activates proteins such as cry protein in the insect’s gut.

10. 3. The solubilization of protein crystals releases and activates proteins such as cry protein in the insect’s gut. 4. The activated protein binds to the specific receptor present in the gut wall of insects, causing pore formation. 5. The pore formation leads to an osmotic imbalance between intracellular and extracellular environments, and cell lysis occurs. 6. As a result, the microvilli are destroyed, the insect ceases feeding, and it eventually dies.

11. Symptom of fungal Infection on Host Loss of appetite, irritability and paralyses. Discoloured patches on integument and increased blood acidity. Body becomes hard and covered with white green mycelial growth. Mummified larvae comply to leaves, stem and fruiting bodies. Death occur within 2 to 3 days depending upon host insect and environmental conditions.