Climate change has already increased the overwintering range of a destructive pest, increasing its resistance to insecticides, and the situation is projected to get worse in the coming decades, new research shows.

Scientists from Rice University in Texas and the Chinese Academy of Agricultural Sciences concluded that the overwintering range of the diamondback moth has grown by more than 925,000 square miles in the past 50 years and projected an increase of 850,000 square miles for every increase of the temperature of 1 degree Celsius.

“Current climate models predict mean global temperatures will increase by 2-6 degrees Celsius during the next 100-150 years,” the study said.

The moth, also known as the cabbage moth, is responsible for more than $4 billion in damage worldwide each year to broccoli, cauliflower, cabbage, kale, mustard, radishes, turnips, watercress, Brussels sprouts and other crops, a Rice news release on the study says. “It is also one the world's most pesticide-resistant species, with a documented resistance to at least 97 insecticides.”

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“Our analysis of global data sets revealed that pesticide resistance levels are linked to the species’ overwintering range: mean pesticide resistance was 158 times higher in overwintering sites compared to sites with only seasonal occurrence,” the report said. A chart accompanying the study shows that the overwintering range supporting survival of 5% or more of the moths was about 30.4 million square miles in 2016. With a 3-degree-Celsius increase, that range could grow to more than 32.6 million square miles.

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