Masud

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Information about Masud

Published on October 17, 2016

Author: masudrana218

Source: slideshare.net

1. BIOCHEMICAL PESTICIDES Presented by- MD.MASUD RANA Jahangirnagar university

2. BIOCHEMICAL PESTICIDES  Naturally occuring pesticides.  Control pests by nontoxic mechanisms.  Biochemical pesticides include substances, such as-  Insect sex pheromones, that interfere with mating  various scented plant extracts that attract insect pests to traps. 2

3. BIOLOGICAL CONTROL THROUGH INTERACTION  Controlling pests relies on following interaction: • Predation • Parasitism or • Ammensalism. Parasitism:  Bacteria used for biological control infect insect via their digestive tract. For example, Bacillus thuringiensis, with at least four sub- species used to control: Lepidopteran (moth,butterfly) Dipteran (true flies). 3

4. Insecticidal toxin of Bacillus thuringiensis • B. thuringiensis is a gram positive soil bacterium that produces a toxin or crystal protein (Bt toxin or Cry) that kills certain insects • The Bt toxin or Cry is produced when the bacteria sporulates and is present in the parasporal crystal.

5. mode of action • The Cry protein is made as an inactive protoxin • Conversion of the protoxin into the active toxin requires the combination of a slightly alkaline pH (7.5-8) and the action of a specific protease found in the insect gut. • The active toxin binds to protein receptors on the insect gut epithelial cell membrane. • The toxin forms an ion channel between the cell cytoplasm and the external environment, leading to loss of cellular ATP and insect death.

6. Genetically Modified Organisms

7. FUNGUS  Fungi that cause disease in insects are known as entomo pathogenic fungi. Examples of entomo pathogenic fungi: – Beauveria bassiana works against white flies, aphids. – Metarhizium spp. Against beetles, spider mites or other pests. – Trichoderma spp. are used to manage some soil borne plant pathogens.

8. MODE OF ACTION OF FUNGI • Invade insects by penetrating their cuticle or skin. • Rapidly multiplies throughout the body. • Death is caused by tissue destruction or by toxin production. • Emerges from insects body by producing spores. • Can spread infection by-Wind, Rain, and Contact with other insects.

9. VIRUS • Baculoviruses are pathogens that attack insects and arthropods. • Insects infected by consuming plant material with viral particles. • Viral infection begins in the insects digestive system but spread throughout the body. • Virus killed insects break open and spill virus particles into the environment.

10. VIRAL ACTION

11. Predation:  Protozoa : protozoa must be applied before outbreaks of disease to effect proper control. Example : Nosema, Vairimorpha used for controlling insects (grasshoppers, mosquitoes etc).  Nematodes: Romanomermis are used to control insects. 12

12. Ammensalism: Streptomyces spp. that have ammensal effects and are useful in agricultural pest control. – Produce Antibiotics such as streptomycin that are effective against bacterial pathogens and – Other substances such as bilanafos that are active against weeds. 13

13. HOW TO APPLY ?  Biopesticides are typically microbial biological pest control agents that are applied in a manner similar to chemical pesticides. Such as-  Soil applied biopesticides: are appliede to the soil.  Contact biopesticides: Generally control pests as a result of direct contact.  Preplant herbicides: are applied to the soil before seeding. 14

14.  Selective biopesticides: only control certain pests  Non-selective biopesticides: control wide range of pests.  Foliar biopesticides: applied to plant leaves, stems and branches.  Postmergent herbicides: apllied after the crop or weed has emerged. 15

15. ADVANTAGES • Do not leave harmful residues. • Substantially reduced impact on non-target species • Can be cheaper than chemical pesticides when locally produced. • Can be more effective than chemical pesticides 16

16. DISADVANTAGES  High specificity, which will require an exact identification of the pest/pathogen .  May require multiple pesticides to be used.  Often slow speed of action.  Often variable efficacy due to the influences of various biotic and abiotic factors.  Living organisms increase their resistance to biological, chemical, physical or any other form of control. 17

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