Among the important subjects covered are astronomy, meteorology, oceanography, new materials, immunology and biotechnology. One of the favorite targets discussed in the book is chitin, a structural polymer of fungal cell walls and insect cuticles. Soon the demand for food by urban populations exceeded the production capacity of the farmers.
Fungal diseases such as rust and blight in wheat were described in the Bible as curses for disobeying the commandments. Most inorganic products are based on elemental sulfur or various copper salts. Consumers would then undoubtedly want to know how much of the insecticide in the plants would find its way into their bodies.
Her graphic presentation of the dangers of these materials sensitized the public to this potential problem. The first consists of chemicals that mimic some of the chemicals found in the insect's body as a result of its physiological cycles. However, the mimics cannot perform the functions of the natural molecule and thus deceive the insect.
One of the first scientists to envision the use of microbes for pest control was the 19th century zoologist Elie Metchnikoff.
In the living world, the largest number of known species, about 800,000, are insects, which is only 13 percent of the estimated number. Their natural enemies are extensively studied in the hope that these natural enemies can one day strengthen the hands of farmers in their fight against the pests. This temporary repair of the midgut occurs because the midgut epithelial cells are routinely shed and replaced.
Usually 4-6 days pass between the time of virus ingestion and the death of the host. However, it was not until the beginning of the 20th century that it was recognized that viruses can infect insects. Alternatively, an infectious cycle of the virus may begin when an insect ingests virus inclusion bodies.
However, mass production of virus from infected larvae or adults and its purification are time-consuming and labor-intensive. This is due to a physiological process that prolongs the life of the virus-infected pest with unfortunate consequences for the farmer. This strategy would involve "grafting" a selected gene that regulates the production of a protein toxin into the genetic makeup of the virus.
The BT preparations remain stable over several years of storage and even in the presence of UV rays from the sun. The ability of the individual toxins to kill the larvae of pests has been extensively investigated using molecular techniques. Scientists around the world are trying to develop better, more effective strains of the Bacillus species.
Penetration of hyphae into the epidermis takes place through wounds, joints between segments or through the senses. The cause of the death of insects is the extensive growth of fungi in the hemolymph and poisoning with a fungal toxin. It is almost like setting a thief to catch a thief and is one of the most promising methods of controlling plant pathogenic fungi.
Some of the Trichoderma species are parasitic on fungi and grow inside the pathogens' hyphae. This method has achieved great success in controlling more than 200 species of insect pathogens in different countries of the world.
The cell wall is not an inert protective shell, but rather a dynamic organelle necessary for cell viability. This means that any major disruption of organization or metabolism will be detrimental to the cell. The chitin content of fungal cell walls varies widely from 3 to 5 percent to about 60 percent. In Sclerotium rolfsii, a root-infecting peanut pathogen, 60 percent of the cell walls are composed of chitin.
The components of the matrix are protein-linked polysaccharides called mannans, which form a kind of cementing material in the cell and also contribute to the flexibility of the cell walls. Of course, the first step to cell wall formation would be chitin synthesis. Inside the walls, chitin is crystalline in nature, hard and resistant to chemicals and enzymes.
The hardening of the cuticle is due to its impregnation with calcium salts or further polymerization with certain chemical compounds or both. The endocuticle is twice as thick as the exocuticle, but colorless and made of chitin and protein. The distribution of chitin types in an organism has functional significance, as chitin from fungal and animal sources cannot be distinguished by X-ray and elemental analysis.
In addition to insects and fungi, chitin is present in the shells of marine invertebrates, such as crabs, oysters, lobsters and shrimp. In an effort to find alternative methods of removing chitin waste, it was accidentally discovered that flooding agricultural land with this waste helped control root-infecting fungi. Synthesis and degradation of chitin are active processes in insects and closely linked to survival. When an insect is starved, its cuticle becomes much thinner because it uses cuticular chitin as an energy source.
The addition of chitin inhibits the entire fungal population and stimulates lytic and antibiotic producing microbes. Chitosan, a common component of the cell walls of Mucor-like fungi, can activate specific genes in plants and can simultaneously inhibit RNA synthesis in some fungi. Although chitosans inhibit fungal growth more effectively than chitin in the laboratory, chitin seems to be more suitable for practical purposes.
The attacks are either an inhibition of chitin and/or glucan formation or an acceleration of their degradation with the help of enzymes. The main enzyme involved in the final step of chitin synthesis is chitin synthase. There is no concrete evidence of what is happening in the cell, but some observations have provided clear clues about chitin synthesis.
With the help of the electron microscope, some clear changes during fungal growth can be seen. Once the biosynthesis of chitin was understood, the researchers had a potential target to hit. It was found that a number of neurotoxins and biochemicals that affect respiration also affect the process of chitin biosynthesis either directly or indirectly.
Both are structurally very similar to UDP-GlcNAc, an active monomer of chitin. Nikkomycins are structurally closely related to polyoxins and are highly specific inhibitors of the enzyme chitin synthase. Once this hurdle is crossed, the possibility arises that the enzymes in the cell can break down or break down the antibiotics. However, the fact remains that these enzyme inhibitors deserve more research if we want to win the battle against pests.
Furthermore, this enzyme also plays an important role in the biosynthesis of essential proteins in human cells. However, if we could find an enzyme that is not represented in humans and non-target animals, but is present in the pest, we might be able to safely find an inhibitor(s) for it and stop the pest.” The allosamides produced by Streptomyces species are structurally very closely related to acetylglucosamine, a basic unit of chitin.
Researchers believe this may be due to differences in the sites on the enzymes from different species where the inhibitors bind before taking effect. If the crop is attacked by pests like Pyrilla, the farmer has to bear a 30 percent yield loss, while his loss for fungal infections, such as blight caused by Ustilago or grass shoot by Mycoplasma, is 15-20 percent. In third world countries, including India, most farmers use chemicals because of their ease of application, affordability and guaranteed results.
Bio-pro- tection in
But because this often damages the protoplasm in the cells, this method is not very popular. Sometimes DNA is encapsulated in closed vesicles called 'liposomes', which are then introduced into the cell. The liposomes fuse with the plasma membrane and empty their contents into the protoplasm. Electroporation has also been used to introduce foreign DNA into the cell. This process involves passing short pulses of electrical current, making the cell membrane temporarily permeable to molecules such as DNA.
For many years it was known that BT could be useful for biological control of insects because it produces anti-insect toxins. Hopefully, insect-resistant corn, wheat and rice will be available on the market by the turn of the century. However, the success of transgenic plants in the fields may bring with it the twin potential problems of biosecurity and destabilization of natural ecosystems.
Given the dangerous effects of chemicals and the obvious danger that transgenic plants pose in the wild, biopesticides are attracting big business. When using natural enemies, it is important to have fast-growing biological control organisms in the fields, which can ultimately make conditions unfavorable for the spread of pathogens. Longer stability of the biopesticide under field conditions is essential to protect crops during the vulnerable period.
One of the essential factors for the success of newly developed biopesticides is the agricultural education and knowledge of the pest and its development cycle. Quality control of the biopesticides includes strict regulation of production standards, production facilities and field performance. Cell wall: A dynamic protective covering of plant, bacterial, or fungal cells required for cell viability.
Polymerization: 'Process by which a compound is formed by joining together a large number of monomers. Many fungi and bacteria are saprophytes; they play an important role in recycling nutrients. When they enter a cell, they take over the cell, making more viruses, usually destroying the cell in the process.