Genetically modified organisms have been used in the U.S. since 1996. They are resistant to pests, and protect crops from harmful insects.

Bruce Tabashnik, head of the UA's Department of Entomology, said a combination of technology and GMOs provides the safest, and most productive way of protecting crops in order to get the best outcome.

However, some bugs are resilient and adaptable to GMOs in certain types of crops. Resistance to GMOs can be seen in as little as two or three years.

Before GMOs, farmers would use dangerous pesticides, oftentimes harmful to humans, to prevent pests from attacking their crops. Tabashnik said using GMOs in a balanced manner is beneficial to both to yields and humans.

GMOs control insects with bacterium called Bacillus thuringiensis. Bt proteins are commonly used as biological pesticides because they kill insects in a safe and effective way, Tabashnik said.

Bt proteins have been used by organic growers for decades. They are safer than most pesticides, and are specific in terms of what insects they kill.

“They have a much narrower spectrum of activity than conventional pesticides, which are usually nerve poisons, and will kill a wide variety of insects,” Tabashnik said. “And, they can be poisonous to people.”

While insect resistance to GMOs is rare, according to Tabashnik, when farmers constantly use the same method, the more likely insects will become immune to GMOs. After many generations, the insects evolve resistance to about anything used to control them, he said.

Depending on the crop, sometimes insects are unable to become resistant to GMOs.

Genetically modified cotton in Arizona is one of these crops, Tabashnik said. This type of cotton has remained effective for more than 16 years.

“One of the things we’ve learned is that it depends on the particular crop, insect, and how we use the GMOs,” Tabashnik said.

Ashley Grove is a journalism student and an intern for Arizona Public Media