Colorado potato beetle (Leptinotarsa decemlineata)

Signs and symptoms of Colorado potato beetle

Management of Colorado potato beetle

Effective Colorado potato beetle management requires an integrated approach that may combine cultural and physical practices, biological control, and careful use of chemical insecticides. Understanding CPB’s life cycle and behavior are key to making informed management decisions and reducing crop losses.

Regular scouting is essential: walk the field in a V-shaped pattern and check 30–50 plants or stalks, depending on plant size. At each stop, count adults, small and large larvae separately, and look for orange-yellow egg masses on leaf undersides. Also record percent defoliation to help guide action thresholds. Thresholds are listed below under Chemical Control. 

Physical Control

• Plastic lined trenches – Install between overwintering site and main crop to intercept migrating beetles overwintering from field edges (adults can not escape the slippery sides of the plastic trench and die).
• Row cover – Use to protect young plants against overwintering adults. Only use if solanaceous crops, like potatoes or eggplants, were not grown in that location the previous season, as beetles may emerge from the soil beneath the covers. 
• Flamers – Apply propane burners for killing adults on small plants
• Tilling after harvest - This strategy can help reduce overwintering beetle populations.

Cultural Control

• Crop rotation – Rotate host crops at least 0.25-0.5 miles from previous years potato fields, as beetles typically overwinter nearby and are more likely to walk to the crop than flying long distances.
• Early harvest – Vine kill potatoes as soon as the crop matures to eliminate or minimize food for second-generation adults that is needed to survive overwinter.
• Trap crop – Plant early-maturing potatoes before the main potato crop; treat with insecticide.

Chemical Control

Application timing. The preferred approach for managing CPB is to make an insecticide application at planting (see options below). This is a preventative approach that is not based on the size of the CPB infestation.

Another approach is to make foliar insecticide applications. Guidelines for determining if and when to spray include the following action thresholds: 1.0 to 1.5 large larvae per plant, or 4 small larvae per plant, or 0.5 to 1.0 adult per plant. However, timing of foliar sprays should consider the phenology of the CPB population (i.e., all stages of CPB in the field).  The best advice is not to wait too long to make the application (e.g., when many large larvae are present) because it will be difficult to control the infestation. Conversely, it is not advised to start too early or else more than one or two applications may be needed to control the infestation, rather than one well-timed application.

Products (examples of those commonly used):

• Spinosyns (Group 5): Spinosad (e.g. Entrust® for organic, or Blackhawk®) and spinetoram (Radiant® SC) are fermentation-derived insecticides that are highly effective on CPB larvae. They are considered reduced-risk and are organic-approved (spinosad), making them popular in organic potato production. Spinosyns act on the insect nervous system via nicotinic receptors (different site from neonics) causing paralysis.
• Diamides (Group 28): The systemic diamide cyantraniliprole (Verimark®) can be applied in furrow at planting to protect young plants from CPB. Foliar applications of cyantraniliprole (Exirel®) and chlorantraniliprole (Vantacor ®) also are effective.
• Neonicotinoids (Group 4A) - Systemic neonicotinoids such as imidacloprid (e.g. Admire®) and thiamethoxam (Cruiser®, Platinum®), have been widely used against CPB, often applied at planting as seed treatments or in-furrow sprays to protect young plants. Acetamiprid (Assail®) can be used as a foliar spray to control CPB. However, these are products known to be harmful to bees, and many states and large retail stores are beginning to phase out use of these products.
• Other products: There are many other registered products for CPB control in potato. Consult your local cooperative extension educator or vegetable entomology specialist for options.
• New products. One of the newest products for CPB management is RNA interference (RNAi) insecticides. In 2023, the first-ever sprayable dsRNA insecticide, ledprona (Calantha®) was approved by the EPA specifically for Colorado potato beetle. Ledprona works by silencing a vital gene in CPB (an enzyme needed for protein digestion), leading to beetle death. RNAi products are highly specific; ledprona is designed to affect CPB and no other organisms. One product that is in the registration pipeline is isocycloseram (Plinazolin® technology), which inhibits GABA gated chloride channel (Group 30). PLINAZOLIN ® technology controls both CPB and potato leafhopper. 

Any time you use a pesticide, you must read and follow the label directions and comply with all applicable laws and regulations related to pesticide use. Also be sure that any pesticide used is approved for use in your country and state/province.

Biological Control

Biological control involves using natural predators, parasites, or pathogens to manage pest populations. This approach reduces reliance on chemical insecticides and supports sustainable pest management.