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Image of apiary training sponsored by DPR, Parlier, CA. June 2014

 Apiary training sponsored by DPR,
Parlier, CA June 2014

Neonicotinoid Reevaluation Progress and Protecting Bee Health

The California Department of Pesticide Regulation (DPR) is at the national forefront of the effort to protect bee health, taking proactive steps and a scientific approach to address concerns about the impact of pesticides on the health of bees and pollinators. One such step includes the reevaluation of certain pesticide products containing the nitroguanidine-substituted neonicotinoid active ingredients, imidacloprid, thiamethoxam, clothianidin, and dinotefuran. As a result of the reevaluation, which included issuance of a pollinator risk determination, DPR determined that additional mitigation measures are needed to protect pollinators from the use of the neonicotinoids in agricultural crops and is developing mitigation measures in the form of regulations.

Public Feedback Webinars

DPR held two webinars on August 11 and 12, 2020, to share information and gather feedback from the public on the proposed pollinator protection mitigation measures for the use of nitroguanidine-substituted neonicotinoids in agricultural crops. The original comment period has been extended. Comments and feedback on the proposal will now be accepted until the end of day on October 30, 2020. Comments can be made by e-mail to or by leaving a voicemail message at 916-445-0003. The webinars were recorded and are available at the links below.

Webinar Materials and Additional Information


In 2009, DPR placed certain pesticide products containing neonicotinoid active ingredients, imidacloprid, thiamethoxam, clothianidin, and dinotefuran, into reevaluation. The reevaluation is based on imidacloprid adverse effects data. These studies indicated a possible hazard to pollinators with two findings: high levels of imidacloprid residue in leaves and blossoms of treated plants and increases in residue levels over time. Thiamethoxam, dinotefuran, and clothianidin are in the same chemical family as imidacloprid, known as the nitroguanidine insecticide class of neonicotinoids, and have similar properties and characteristics.

DPR partnered with U.S. Environmental Protection Agency (U.S. EPA) and Pest Management Regulatory Agency (PMRA) Health Canada to assess risks to honey bees from neonicotinoid active ingredients. The agencies worked together to ensure that the required studies, and methods and procedures used to conduct studies on the effects of neonicotinoids provide useful and reliable information across the board to all three agencies for use in guiding their regulatory actions. DPR played a lead role in the development of the tiered honey bee risk assessment process in collaboration with the U.S. EPA, PMRA Health Canada, and the 2011 SETAC Pellston Workshop on Pesticide Risk Assessment for Pollinators.

As a part of DPR’s reevaluation, comprehensive data for pollinators was required. Registrants submitted numerous studies, which DPR evaluated to identify risks to pollinators. In July 2018, DPR published the California Neonicotinoid Risk Determination. On January 2019, DPR published an addendum to the July 2018 California Neonicotinoid Risk Determination after receiving additional information and in an effort to report the most accurate information possible.

Following the publication of the Risk Determination and addendum, DPR met and continues to meet with stakeholders to learn about commodity cultivation practices and neonicotinoid use patterns in the field while also meeting with registrants to discuss potential mitigation strategies. DPR continues to work towards adopting mitigation measures to protect pollinator health.

For more information on neonicotinoid reevaluation, visit the Reevaluation Program page to view the current semiannual report summarizing reevaluation status.

Other Information and Proactive Actions to Protect Bee Health

For content questions, contact:
Denise Alder
1001 I Street, P. O. Box 4015
Sacramento, CA 95812-4015
Phone: (916) 324-3522