Insecticide Resistance: Genes For Pest?Donnie Day

Overview What is a GMO? What is Bacillus thuringiensis ? What is Bt Crops? How does it work? Bt Safety Concerns

What is a GMO? When a gene from one organism is

purposely moved to improve or change another organism in a laboratory

It is also sometimes called "transgenic" for transfer of genes

GM techniques also allow traits from different organisms to be applied, such as pest resistance.

How its done Isolation of the gene(s) of interest Insertion of the gene(s) into a transfer

vector Plant transformation Selection of the modified plant cells Regeneration into whole plants via tissue

culture Verification of transformation Testing of plant Safety assessment

What is Bacillus thuringiensis?

Bacterium that produces crystals protein (cry proteins), which are toxic to many species of insects.

Bt belongs to the family of bacteria, Bacillus cerus

Bt is also used in urban aerial spraying programs, and in transgenic crops.

What is a Bt Crop?

Plants that have been modified with short sequences of genes from Bt to express the crystal protein Bt makes.

How does it work?

1. Insect eats Bt crystals and spores. 2. The toxin binds to specific receptors in the gut and the insects stops eating.

3. The crystals cause the gut wall to break down, allowing spores and normal gut bacteria to enter the body.

4. The insect dies as spores and gut bacteria proliferate in the body.

Bt Safety

Bt products are found to be safe for use in the environment and with mammals.

Bt has not been shown to have any chronic toxicity or any carcinogenic effects.

Concerns Resistance

Cross-contamination of genes

Invasiveness

How? In a population of insects there may be

a few individuals that carry the genes for resistance

With every generation the number of resistant insects increase.

Unavoidable?

diamondback moth is the only insect found to have developed resistance

Minimizing Resistance Alternate Bt applications with synthetic

insecticides

Crop rotation

Refuge Planting

Refuge Planting

Summary What is a GMO? What is Bacillus thuringiensis ? What is Bt Crops? How does it work? Bt Safety Concerns

Questions ?