Diamondback moth has evolved resistance to 104 insecticide active ingredients, leaving brassica growers with almost no chemical options

The diamondback moth (Plutella xylostella) has developed documented resistance to 104 unique insecticide active ingredients across 1,099 recorded cases, making it the world's number-one insecticide-resistant pest. In the fall 2024 and spring 2025 growing seasons, growers across Arizona and California reported outright control failures against diamondback moth in broccoli, cabbage, and cauliflower fields. The moths now shrug off chlorantraniliprole (Coragen), cyantraniliprole (Verimark), emamectin benzoate (Proclaim), spinetoram (Radiant), and even Bt aizawai (XenTari) -- products that represented the last reliable lines of defense. This matters because brassica crops -- broccoli, cabbage, kale, cauliflower -- are a $3+ billion U.S. market, and diamondback moth is their primary insect pest worldwide. When control fails, growers don't just lose yield; they lose entire harvests. A single uncontrolled generation can destroy a field in days because the larvae bore into the growing points and heads, making the crop unmarketable. Growers respond by spraying more frequently and at higher doses, which accelerates resistance further, poisons beneficial insects that would otherwise provide natural control, and increases production costs by hundreds of dollars per acre. The global cost of managing diamondback moth is estimated at $4-5 billion per year, much of it wasted on chemicals that no longer work. This problem persists because of a structural mismatch between how insecticides are used and how resistance evolves. Growers plant brassicas year-round in warm climates like Arizona, California, and the Southeast, giving the moth continuous generations with no break in selection pressure. Each generation is roughly 3-4 weeks, meaning a single growing season can impose 8-10 rounds of selection on the same population. The moth also migrates long distances, so resistant genes spread rapidly across regions. Meanwhile, the pipeline for new insecticide modes of action has slowed to a trickle -- no genuinely new class has been commercialized for Lepidoptera in over a decade. Mating disruption and biological controls exist but are not widely adopted because they require more management expertise and don't offer the quick knockdown growers need when a crop is under immediate attack. The result is a treadmill: each new chemistry buys a few years before resistance catches up, and the interval keeps shrinking.