Climate change will continue to help a pest flourish and hurt California nut tree crops, university study predicts

A navel orangeworm fly on a pistachio.
(University of California photo)

California is the world's leading producer of almonds, walnuts and pistachios, but climate change may render a pest that threatens these crops an even bigger threat, according to a new scientific paper. 

The navel orangeworm costs nut growers millions of dollars in losses every year. The insect produces three or four generations per year, but a recently published study from the University of California predicts that a warming climate will help the pest thrive, Liza Gross reports for Inside Climate News. 

According to the study, "warming temperatures may help the dreaded pest wreak even more havoc in at least two ways, including expanding their range into previously inhospitable areas and accelerating their reproductive rates, boosting their numbers," Gross reports. "A fifth navel orangeworm generation will emerge in almonds and walnuts in three southern counties by 2040 and eight more by 2100, according to the predictions. But in pistachios the fifth generation appeared in seven southern counties by 2040 and 17 counties by 2100. The findings flag the state’s pistachio crop—valued at nearly $2 billion—as the most vulnerable to damage and economic losses. "