On January 1 of this year a new law went into effect in California, greatly limiting the use of a pesticide class known as neonicotinoids. Originally developed in the 1980's, these pesticides became the most widely used class of insecticides in the world. Their initial promise was based on desirable qualities such as reduced toxicity to people and pets compared to other insecticides in use at the time. Now however, after 40 years of use, studies are showing that these insecticides are having adverse effects on pollinators and beneficial insects, including bees and lady beetles, as well as on aquatic invertebrates.
What are neonicotinoids?
Neonicotinoids are chemical toxins that attack the nervous systems of insects. They are widely used in horticulture, agriculture, and in urban settings, including parks. Neonicotinoid pesticides are defined as any pesticide containing one or more of the following five active ingredients: acetamiprid, clothianidin, dinotefuran, imidacloprid, and thiamethoxam. The pesticides have been used both in agricultural and residential settings, and are sometimes combined with a fertilizer, herbicide or fungicide. These products have been available at retail for homeowner use, although you might not be aware of their presence in a combination product unless you check the active ingredients list.
Why are these chemicals being restricted?
After several decades of use researchers are beginning to see associations between neonicotinoid use and serious adverse effects on non-target populations alongside environmental contamination. The chemicals have a systemic action, meaning they are active within an entire plant. In some cases, the active ingredient makes its way into the plant's pollen and nectar, poisoning the pollinators that feed on them. It can also be found in seeds, carrying the poison into the next generation plant. In addition, neonicotinoids are water-soluble and long-lived. Runoff from soil drenches, irrigation or even rain can wash the chemicals into creeks and storm-water systems. Earthworms, soil microorganisms, aquatic invertebrates, predatory beetles, bees, and parasitic wasps are all susceptible to these very toxic chemicals.
What does the new California state law say?
The law, as presented at https://www.cdpr.ca.gov/docs/registration/canot/2024/ca2024-18.pdf reads: Effective January 1, 2025, neonicotinoid pesticide products used for non-agricultural uses on outdoor trees, turf, or ornamental plants can only be sold by licensed dealers and possessed or used by California certified commercial applicators. The law defines the term “neonicotinoid pesticide” as a pesticide containing any of the following five active ingredients: acetamiprid, clothianidin, dinotefuran, imidacloprid, and thiamethoxam.
There are some instances where a homeowner could continue to use neonicotinoids, but the law effectively allows the sale of these products by certified commercial applicators only, meaning they will generally no longer be available at retail. For guidance from the state on interpreting the law, visit https://www.cdpr.ca.gov/docs/county/cacltrs/penfltrs/penf2024/202412.htm.
How do I manage my pest problem without neonicotinoids?
While the law allows homeowners to use neonicoinoids on a backyard fruit or vegetable garden, there are other choices. Most uses by homeowners are for pests such as aphids or soft scales. An integrated pest management (IPM) approach suggests using other, safer and effective products such as horticultural oils or soaps, knowing which insects are pest predators, and following good cultural practices that reduce plant susceptibility to pests.
The UC IPM website offers information on how to manage a wide variety of pests, as well as how to protect beneficial insects (those that are natural enemies of the pests).
- UC IPM: https://ipm.ucanr.edu/PMG/menu.homegarden.html?src=302-www&fr=3723
- Protecting beneficial insects: https://www.ci.richmond.ca.us/1720/Hazardous-Waste
What should I do with the neonicotinoids I already have?
If you have neonicotinoid products in storage, you can take them to the Hazardous Waste Disposal site nearest you for disposal.
- East County: https://www.deltadiablo.org/household-hazardous-waste
- Central County: https://www.centralsan.org/hhw
- West County: https://www.ci.richmond.ca.us/1720/Hazardous-Waste
Further Reading
If you want to learn more about neonicotinoids and their impacts, or about pesticide use generally, the following sites are quite useful.
- Learn about pesticides and their associated risks: https://ipm.ucanr.edu/home-and-landscape/pesticide-active-ingredients-database/#gsc.tab=0
- Understanding neonicotinoids: https://www.xerces.org/pesticides/understanding-neonicotinoids
- Summary of the widespread risks of neonicotinoids: https://www.xerces.org/publications/guidelines/beyond-birds-and-bees
- More information about the new law: https://ucanr.edu/blogs/blogcore/postdetail.cfm?postnum=61653
Help Desk of the UC Master Gardeners of Contra Costa County (RDH)