After Eradicating Pink Bollworm, Arizona Farmers Hope to use GMO Cotton to Target Other Pests

Cotton farmers in Arizona started planting genetically modified cotton in 1996 in an effort to eradicate an invasive species of moth from Asia or Austrailia known as the pink bollworm.

Pink bollworm caterpillars eat the seeds of cotton plants and damage cotton fibers, and in the 1990s and early 2000s, they were a big problem in Arizona. Then farmers tried a new method to combat the insects: planting genetically modified cotton, called Bt cotton, that is toxic to pink bollworms.

His study shows that eliminating the pink bollworm saved cotton farmers in the United States $192 million from 2014 to 2019 and helped reduce pesticide use in Arizona cotton fields by 82%. Though it’s been years since a pink bollworm has been spotted in the state, many Arizona farmers like Ollerton continue to use genetically modified cotton, and are turning their eyes toward other types of cotton pests.

Over time, Tabashnik worried that if farmers planted nothing but Bt cotton, all of the regular pink bollworms would die off and the only ones left would be the resistant pink bollworms, which would cause all future generations of pink bollworms to be resistant to the toxin and make managing the population even harder.

To combat this problem, Arizona farmers were required to plant non-genetically modified cotton as at least 4% of their overall cotton crop so that some non-resistant bollworms would survive and mate with the resistant bollworms. In Burkina Faso, a country in western Africa famed for its high-quality cotton, companies introduced Bt cotton in 2008 after being devastated by bollworm pests.

Ollerton said he hasn’t noticed much of a difference between regular cotton and genetically modified cotton in the U.S., except that in some genetically modified cotton varieties, it was harder to open up the cotton bolls for picking. He has continued to use the genetically modified cotton even after getting rid of pink bollworms because they are useful against other types of pests as well, such as the native cotton bollworm, also known as a corn earworm.

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