Bacillus Thuringiensis
Bacillus thuringiensis or BT is a naturally occurring bacterium in soil, water, air, and even on trees and leaves. Which is not harmful to people, animals and plants, the properties of the BT bacteria can create toxins to kill insects by eating insects and causing insect death. Therefore, agriculture has introduced the infection. BT is used to control herbivorous insects.
Dr. lshiwata was the first Japanese scientist to find the infection. By isolating Bacillus thuringiensis strains. From a dead silkworm Later, in 1909-1912, Dr. Berliner discovered the spore-producing bacteria from the Mediteranean Flour Moth (Anagasta Kuehniella), found in thuringen. Bacillus Thuringensis
BT or Bacillus thuringiensis Its shape is similar to BC (Bacillus cereus), but differs in that BT can produce delta endotoxins. Which has the shape of a rhombic seal This toxin is used to control pests. Not resistant to heat It consists of a group of protein molecules. Which contains both toxins and enzymes in the form of dumbbells
BT toxin can have 4 types.
- Alpha exotoxin
Alpha exotoxin was created before spore formation. Have a low molecule But can tolerate heat up to 120 degrees Celsius for more than 10 minutes by this toxin is toxic to worms, flies, caterpillars and caterpillars by affecting the Hormones system. And metabolic processes When insects ingest this toxin Change the shape The adult is not perfect. Also, the life cycle is short and cannot continue to reproduce. Currently, this toxin is not allowed to be used in pest control.
- Beta exotoxin
Beta exotoxin is a toxin that occurs outside the cell. Not resistant to heat and water soluble, nucleotide compounds are formed during the vegetative growth phase.They are highly toxic to insects at levels lepidoptera, diptera, and coleoptera. If it is a pupa, it may have a different shape. Or if it is an adult, it may not be perfect
EPA united state does not permit the use of this toxin contained in BT products for pest control.
- Delta endotoxin
This toxin is used to control pests. They come in a variety of names, such as crystal toxin, parasporal inclusion body, composed of protein molecules. (proteinaceous crystal), which contains toxins, enzymes, together to form dumbbells.
- Gamma exotoxin
This toxin is not heat tolerant. Susceptible to weather When the temperature is above 60 ° C, it will be destroyed within 10-15 minutes. The method of infestation of this toxin is not yet known.
Kill bugs using bacteria BT
BT is a beneficial bacteria that can be used to kill pests in the larva or worm stage. The larvae have to ingest BT bacteria. The toxins that are ingested are in the form of protoxin (not yet toxic) and when the infection enters the larva's stomach. Which has a relatively high alkaline gastric juice, thus causing the digestion of Protoxin by protease (Proteolytic) into Active Toxin (toxins) by this toxin will enter the cell wall of the stomach. And destroying the cell wall Later, the alkaline digestive juice will follow the lesions in the hemocoel of the insect larva. The spores that the larvae have ingested will reproduce in the planes and another part will go into the wound. To divide in various tissues in the insect larva Which causes Septicemia. In the end, the insect larvae die.