Using Bacillus thuringiensis to replace standard pesticides for crops

Farmers have long dealt with the struggle of losing their crops to ravenous insects and being forced to use pesticides to protect their harvest. The problem with many of these pesticides is that they are broad-range type pesticides meaning that if a farmer sprays this pesticide to kill a specific beetle, that the poison will kill the beetle but may also kill any other insects exposed whether they are beneficial or not. These pesticides are also often harmful to other species including mammals, fish, and birds. In same locations, the level of pesticides applied to the crops to keeps the insects away is well over the regulated amount that is safe for consumption. Not to mention the cost of the pesticides and the cost of fuel to have the pesticides spread around. To combat this problem, scientists have been looking into the idea of modifying certain crops to utilize the bacterium  Bacillus thuringiensis.



Bacillus thuringiensis (Bt) is a common soil bacterium that produces produces poisonous proteins. The scientists singled out the toxin-making gene from the bacterium and could implant it into whatever crop they desired, in this case, an eggplant. Implanting the gene would allow the eggplant to produce the toxins on its own, effectively producing its own pesticide. The toxin in B. thuringiensis works by being ingested in crystal form where the crystals separate and bind to proteins on the gut cells and cause them to burst. Propelled by the movement of its hemolymph, the insects gut juices are pushed into its body cavity where it is left to succumb to infection, paralysis, and death. In the case of the eggplant, Bt eggplants would kill only the fruit and shoot borer and possibly closely related species, leaving other insects and creatures unharmed. Bt was a popular spray choice for organic farmers because "In addition to their selective lethality, the bacterial toxins degraded in sunlight and washed away in rain, rather than contaminating wild habitat and sources of drinking water." meaning that this pesticide had few side effects per say to the environment. The only catch to this pesticide is that it needed to be applied very frequently, often every three to four days.

This is where the scientists come in. If the scientists effectively implant the toxin making gene from the bacterium into the crops than the crops will no longer need to be sprayed. The crops will create their own toxin which has been tested to be selectively lethal, making it relatively harmless to humans and would save farmers loads of money on fuel because the plants would no longer need to be sprayed. Scientists mention using agrobacterium tumefaciens to implant the B. thuringiensis gene into the crops, as the agrobacterium evolved to inject material into plants in order to aid infection. With genetically modified plants such as these, farmers could see a rapid increase in profits because they would be generating a stronger crop yield and they would save on costs for transporting and spraying the pesticides.

Article:       http://www.scientificamerican.com/article.cfm?id=farming-a-toxin

Sub-Article:     http://onlinelibrary.wiley.com/doi/10.1046/j.1365-313X.2002.01401.x/full