Bacillus thuringiensis...more than just for corn.

One of the hot button issues among the general public is the use of  bio-engineering to modify organisms or GMO's.  While genetic engineering can take many forms, plants intended for human consumption are commonly the most scrutinized GMO's.  Perhaps the most infamous of these is Bt (Bacillus thuringiensis) corn.  Bt Corn is corn that has been modified with genes from the endotoxin producing bacterium, Bacillus thuringiensis (Bt).  This bacterium and it's various strains have been used directly as a biopesticide (endospores) for a number of years with different strains proving to be more effective at insect suppression than others. In most cases, as can been seen in the table below, Bt is not spliced into a plant genome but applied to plants and other surfaces with the purified endospores sprayed much like a traditional pesticide.

Table 1. Primary strains of Bacillus thuringiensis used in managing insects.

Bacillus thuringiensis strain (Common name)	Susceptible insects
aizawi	Many Lepidoptera larvae
kurstaki	Many Lepidoptera larvae
israelensis	Larvae of mosquitoes, black flies, fungus gnats
japonensis	Larvae of scarab beetles (Coleoptera: Scarabaeidae)
tenebrionis (san diego)	Larvae of leaf beetles (Coleoptera: Chrysomeldiae)
CrylAb delta-endotoxin1	Many Lepidoptera larvae
Cry3Bb1 variant1	Corn rootworm larvae (Coleoptera: Chrysomelidae)

¹Only used in production of genetically modified crops (Cranshaw, 2014)

The application of  Bt as a sprayed biopesticide and not spliced into plant genomes may be surprising  to some individuals.  In fact, Bt is the most widely used biopesticide in the world. An excellent overview of how and when Bt is used is provided here: Bt fact sheet.  Also, despite many people's fear of Bt crops, endospores of Bt have been applied to organic and commercial crops for years.  For even more details about Bt visit: Bt & Organic Crops.  

Despite the  long safety record for Bt products fear of eating or using products with Bt remains.  Hopefully, this blog post provided a short factual introduction to the uses of Bt in modern agriculture for the uninitiated.