Bacillus thuringiensis
Type: Insecticide
Mode of Action: Cry Toxins
Common Product Names: Agree WG & Dipel
What is it?
Bacillus thuringiensis is a gram-positive, soil-dwelling bacterium. It has been used as a biological pesticide since the 1920s and is known for its safety to humans, animals, and non-target organisms. Bt's specificity to certain insect pests makes it a favored choice in integrated pest management (IPM) programs and organic farming. It acts as a contact insecticide and is highly selective, primarily targeting caterpillars and larvae of certain insect species. Results from Bt applications can be seen within 1-2 days, with the most noticeable effects occurring as the insect larvae stop feeding and eventually die.
How does it work?
When insect larvae ingest Bacillus thuringiensis spores and crystalline (Cry) proteins, the alkaline conditions in the insect's gut dissolve the crystals, releasing the Cry toxins. These toxins bind to receptors on the gut cells, forming pores that cause the cells to rupture. This leads to septicemia and death of the insect larvae within a few days.