University of Arizona entomologists and UA Cooperative Extension specialists made key contributions to a landmark achievement announced by the United States Department of Agriculture on Oct. 19 that the pink bollworm has been eliminated from all cotton-producing areas in the continental United States, 100 years after the voracious insect was detected.

Researchers at the UA College of Agriculture and Life Sciences and Cooperative Extension have been studying the pink bollworm, one of the world's most devastating crop pests, for decades. Before its eradication, the invasive insect often completely destroyed cotton fields despite growers' efforts to control them with insecticides.

"The eradication of the pink bollworm, announced today, is a great achievement that will benefit cotton growers throughout Arizona and the Southwest," said Bruce Tabashnik, who heads the UA Department of Entomology and is a member of the BIO5 Institute. "This stunning success came from decades of teamwork, with effective collaboration among growers, biotech companies, the USDA, the Arizona Department of Agriculture and University of Arizona extension and research scientists."

The UA conducted early testing on Bt cotton, which is genetically engineered to control pink bollworm by producing caterpillar-killing proteins from the bacterium Bacillus thuringiensis. The Bt proteins are not toxic to people or wildlife.

UA entomology specialist Peter Ellsworth participated in the testing and led the development of integrated pest management programs for cotton.
Since 1996, UA scientists have led a resistance management program that has been essential in suppressing the pink bollworm and stopping it from developing resistance to Bt cotton in Arizona. Tabashnik led the establishment of the "refuge strategy," the primary approach used worldwide to delay the adaptation of insect pests to genetically engineered crops.

Cotton growers have not had to spray for pink bollworm since 2008. That fact, combined with integrated pest management programs, has saved growers more than $20 million per year while increasing safety for growers and improving environmental quality.

A team of entomologists from the UA and the USDA was recently awarded a USDA grant to continue pink bollworm research in Arizona through 2021. The researchers hope to gain a better understanding of pink bollworm resistance to Bt cotton that has evolved in India and other parts of the world so if the pest is reintroduced to Arizona, the tools will be in place to defeat it again.