Delta endotoxin

Delta endotoxin is a type of toxin produced by the Bacillus thuringiensis (Bt) bacterium. It is a crystalline protein that is toxic to many species of insects, but not to humans or other mammals. The toxin is used in biological pest control and is the active ingredient in many Bt-based insecticides.

Structure and Function

Delta endotoxin is a protein that is produced in the form of a crystal by the Bt bacterium during sporulation. The protein is encoded by the cry gene, which is located on a plasmid within the bacterium. The toxin is inactive in its crystalline form and must be ingested by an insect to become active.

Once ingested, the alkaline conditions in the insect's midgut cause the crystal to dissolve and the toxin to become active. The toxin then binds to specific receptors on the lining of the midgut, causing the formation of pores in the gut wall. This leads to the death of the insect by cell lysis and septicemia.

Use in Pest Control

Delta endotoxin is used in biological pest control due to its specificity and safety. It is toxic to a wide range of insect pests, including lepidopteran, coleopteran, and dipteran species, but is not harmful to non-target organisms such as humans, other mammals, birds, or fish.

The toxin is used in a variety of ways in pest control. It can be applied directly to crops as a spray, or it can be incorporated into the genetic material of crops through genetic engineering, creating Bt crops that produce the toxin themselves.

Safety and Environmental Impact

Delta endotoxin is considered safe for use in pest control due to its specificity and lack of toxicity to non-target organisms. However, there are concerns about the potential for insects to develop resistance to the toxin, particularly in the case of Bt crops. This has led to the development of resistance management strategies, such as the use of refuges of non-Bt crops.

The environmental impact of delta endotoxin is generally considered to be low. The toxin is biodegradable and does not accumulate in the environment. However, the widespread use of Bt crops has led to concerns about potential impacts on non-target insects and the broader ecosystem.

See Also

• Bacillus thuringiensis
• Biological pest control
• Bt crops
• Insecticide resistance