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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 bees and pollinators health.


In 2009, DPR initiated the reevaluation of certain pesticide products containing four neonicotinoid chemicals: imidacloprid, thiamethoxam, clothianidin, and dinotefuran. Reevaluation is the legal mechanism that allows DPR to require the companies who have registered products for use in California to conduct tests and submit data for analysis by DPR scientists. The purpose of the reevaluation process is to provide DPR with a better understanding of the effects of neonicotinoids use on pollinators and provide a credible scientific basis for potential regulatory action to eliminate any significant impact resulting from their use on bee health.

DPR is partnering with scientists at the U.S. Environmental Protection Agency’s (U.S. EPA’s) Office of Pesticide Programs and Pest Management Regulatory Agency (PMRA) Health Canada 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. A unified approach across jurisdictions is critical as bees and beekeepers are not limited by state borders, nor are their importance to agriculture and society.

A considerable volume of scientific research has been required to be conducted in specified ways as designed by DPR or in collaboration with its partners to elicit the most important and useful data for regulatory purposes. Much of this data has been submitted and evaluated. However, there is more work to be done in order to assure that any actions taken actually address the perceived decline in bee health.

Each of the four neonicotinoid pesticides have different application rates for specific crops, requiring a substantial number of studies to understand the impact of the different pesticides using the application methods used for each crop group. Studies were required for each of the four neonicotinoids as used in the most relevant representative situations to determine the level of residue that remains in the pollen, nectar, and leaves of plants after multiple applications – residue if found in high enough levels, could result in lethal exposure to adult pollinators. Tests were then required to determine what levels of neonicotinoid pesticide would have lethal effects on pollinator larvae. Finally, U.S. EPA required higher tiered honey bees studies with input from both DPR and PMRA Health Canada. Tier II studies, or honey bee feeding studies, examine the effects on colonies following exposures to known concentrations of a pesticide in a food source fed to a bee colony. Tier III studies, or full field studies, is a field-level test that looks at long-term effects under environmentally realistic exposure conditions. Each set of requirements pushed the research one step further after inconclusive or preliminary results and analysis showed no likely significant hazards from neonicotinoid use under existing labels. DPR anticipates receipt of the final results of these studies by the end of 2016.

Other Information and Proactive Actions to Protect Bee Health

  • DPR protects honey bees from the effects of pesticides by working with County Agricultural Commissioners, agricultural producers, beekeepers and other agencies to develop and implement regulatory measures as well as voluntary measures to Protect Bee Health.
  • DPR continues to work closely with the U.S. EPA and PMRA Health Canada. To protect bees and other pollinators DPR collaborated on making product labels (instructions) much easier to understand. The labels clearly explain that the uses of some neonicotinoids pesticide products are prohibited where bees are present. The updated labels have a bee advisory box and icon with information on routes of exposure and spray drift precautions. DPR made it a priority to review the amended labels in order to get them out into the California marketplace. All affected California products contain the pollinator protection label language.
  • Reevaluation Timeline
  • Reevaluation Notice, PDF (59 kb)
  • List of Products Included in Reevaluation, PDF (110 kb)
  • Semiannual Report Summarizing the Reevaluation Status of Pesticide Products, PDF (396 kb) (See pg. 10 for update on neonicotinoids / 2014)

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