Insecticide resistance on the rise: Six-year study reveals growing resistance of Colorado potato beetles to key insecticides

A comprehensive six-year research study, published recently in PLOS ONE, reveals alarming trends in pesticide resistance among Colorado potato beetles (CPB) in the Czech Republic. The Colorado potato beetle is an important potato pest with known resistance to pyrethroids and organophosphates.

A research team in the Czech Republic embarked on a six-year study to monitor resistance levels across various regions of the country, aiming to assess the effectiveness of current pest management practices.

The research, spanning from 2017 to 2022, monitored 69 CPB populations, uncovering significant resistance to commonly used pesticides, including pyrethroids, organophosphates, and neonicotinoids. After the restriction of using chlorpyrifos, thiacloprid and thiamethoxam by EU regulation, growers expressed a need for information about the resistance of CPB to insecticides and recommended resistance-breaking strategies.

The study involved collecting beetle samples from potato fields annually and subjecting them to bioassays to determine their susceptibility to different classes of insecticides. The researchers focused on pyrethroids, organophosphates, and neonicotinoids, as these have been widely used in potato farming.

Key Findings

The study’s findings are concerning for the agricultural community. High levels of resistance were detected across all three classes of insecticides. Notably, resistance to neonicotinoids was expected to decrease due to EU-imposed restrictions, but the results showed otherwise. This suggests that the beetles have retained their resistance traits, potentially due to cross-resistance mechanisms or other factors.

Pyrethroids and organophosphates, often used as alternative treatments, also showed diminished effectiveness, with many beetle populations exhibiting resistance that renders these chemicals largely ineffective. The persistence of resistance across multiple insecticide classes underscores the adaptability of CPB and the challenges of relying on chemical controls alone.

Implications for Potato Farming

For potato farmers in the Czech Republic, these findings underscore a growing crisis. The Colorado potato beetle remains a significant threat to potato yields, and the declining effectiveness of traditional insecticides leaves few viable options for control. The study highlights the need for an integrated pest management (IPM) approach that incorporates non-chemical methods, such as crop rotation, biological control, and the use of resistant potato varieties.

The researchers also stress the importance of continuous monitoring of CPB populations to track resistance trends and adapt pest management strategies accordingly. Without such measures, farmers may face increasing difficulties in protecting their crops from this resilient pest.

Call to Action

The study concludes with a call to action for both researchers and policymakers. The persistence of pesticide resistance in Colorado potato beetles, even amid regulatory changes, indicates that more robust and diverse strategies are needed to manage this pest effectively.

The researchers write: ″CPB control in conventional potato growing should be based mainly on diamides and spinosad. However, using of these two groups for a sustainable antiresistance strategy is insufficient. Antiresistance strategies in the control of CPBs should comprise careful monitoring of CPB resistance to the insecticides used, the extension of the spectrum of insecticides registered to control CPBs… and the determination of baseline susceptibility to newly registered insecticides.″

Source: PLOS ONE. Read the open-access research paper here

DOI: https://doi.org/10.1371/journal.pone.0303238

Research team: Frantisek Kocourek, Petr Dolezal, Ervin Hausvater, Tereza Horska, Bruno Sopko, Petr Sedlak, Vladimira Sedlakova, and Jitka Stara