The Bacillus thuringiensis toxins,more commonly known at Bt,have been a big boon for the agriculture industry for the past two decades. Even so, the emergence of resistant insects has caused concern for the technology’s long-term viability.
A new study published by Harvard University and Monsanto scientists may have just come up with an answer to the problem.
As background, Bt toxins work by binding to certain receptors in the insect’s gut: imagine a very specific lock fitting a very specific key. Bt resistance happens when these receptors are mutated or even deleted from the target pests.
The scientists hypothesized a way to bypass receptor-related resistance using a method called phage-assisted continuous evolution (PACE), which rapidly evolve Bt toxins to increase activity against sensitive and resistant insect larvae by 335-fold.
The result? “Lethality” that approaches the effectiveness of wild-type Bt toxins against resistant insects. In other words, Bt technology just got a reset button.
“These results establish an approach to overcoming Bt toxin resistance and provide a new platform for the rapid evolution of other protein-binding biomolecules,” the researchers conclude in their findings, which have been published in the scientific journal Nature.
Tom Malvar, insect control discovery lead at Monsanto, says one of the end goals is better product durability.
“This gives us an opportunity for long-term durability and allows us to stay ahead of insect resistance,” he says. “Before, our only option was to look for new Bt proteins in the wild. This new technology allows us to use the same process as natural evolution, but engineer and speed up that process in the lab.”
Malvar says Monsanto will pursue and apply PACE technology into other areas of the agriculture industry.
“The initial application is insect control, but we see how it could be used for new herbicide or disease traits, or even helping crops to adjust to changes in climate,” he says. “We see a lot of applications for it.”