Threats to Monarchs from Pesticides
There are three types of pesticides. Within each category there are some that are natural and other that are synthetic, or chemical.
Insecticides kill insects by attacking their nervous systems, hormones, or protective coatings. Among the most harmful synthetic insecticides are the neonicotinoids such as imidacloprid (e.g., Merit). Some natural insecticides, such as neem oil, can be harmful to monarchs whereas others, like kaolin clay and insecticidal soap, are unlikely to cause harm.
Herbicides kill unwanted plants like weeds. They can also be very dangerous to insects and other animals (including humans). Examples of particularly dangerous chemical herbicides are DDT, 2,4-D (e.g., Weed-B-Gon) and glyphosate (e.g., Roundup). Some natural herbicides generally considered safe for pollinators are clove and citrus oil.
Fungicides prevent or treat disease caused by fungi like powdery mildew or rust. Examples of natural fungicides include sulphur and potassium carbonate. Examples of synthetic ones are myclobutanil (e.g., Immunox) and clorothalonil (e.g., Daconil).
A Very Brief History of Approaches to Pest Management
For thousands of years, human used natural substances such as sulphur to kill insects attacking their crops. Then in the 1940s chemical pesticides -- also called synthetic pesticides – were developed and became widely used on agricultural crops.
Harmful to a wide array of plants and animals other than the target species, synthetic pesticides are also known for their persistence, often lingering in soil, water, and living organisms for decades.
Concerns about the harmful effects of synthetic pesticides arose shortly after their development. In the following decade scientists developed an approach called “supervised insect control,” which advocated supporting natural-enemy populations in an area and using synthetic pesticides only as a last resort.
Throughout the 1960s, this approach was further refined, resulting in Integrated Pest Management (IPM), an approach that is widely used in many agricultural and open spaces as well as in urban areas.
Two individuals, Ray Smith and Perry Addison are generally credited as leaders in the development the Integrated Pest Management approach.
Smith received his PhD in entomology from UC Berkeley, and joined the faculty in 1941.
In 1972, he became associate project director of the Huffaker Project which coordinated the research of scientists at 18 universities regarding IPM.
One of his close associates on the Huffaker Project was Perry L. Adkisson.
Born on a farm in Arkansas, Perry Adkisson received a PhD in entomology from Kansas State University. He because a professor at Texas A&M University in 1958, and eventually served as the Chancellor.
Smith and Adkisson were awarded the World Food Prize in 1997 for their achievements in implementing IPM in the US and in developing countries.
Just What is Integrated Pest Management?
Step one: Prevent pests and their damage by managing the ecosystem. For example, grow a healthy crop that can resist pest attacks or using disease-resistant plants. This involves looking at the environmental conditions that affect the pest’s ability to thrive and then creating conditions that are unfavorable for it.
Step two: Monitor the site to identify the pests and note the damage they have caused. This information is key to knowing how much of a problem the pest poses.
Step three: Figure out a combination of management approaches — including biological control (e.g., beneficial insects and natural enemies), cultural control (e.g., crop rotation), physical control (e.g., traps), and as a last resort, chemical control (targeted pesticide use).
Is IPM used in Marin?
YES! Marin is Very Supportive of IPM
Areas in Marin that are managed by the federal government adhere to the IPM approach. IPM is cited as a governing principle the within the Golden Gate National Recreation Area and Point Reyes National Seashore, for example. Herbicides are used as little as possible, and mostly for removing invasive non-native plants. Similarly, insecticides are rarely used and typically involve only targeted approaches such as wasp sprays in public access areas. An exception to this approach, the controversial use of glyphosate in the ongoing Coastal Dunes Restoration Project was adopted only after years of attempting other methods for eliminating iceplant and beachgrass had failed.
Marin County has also endorsed the IPM approach. Marin is a strong advocate for IPM. The IPM Commission is charged with overseeing implementation of the Marin County Integrated Pest Management policy and as well as planning, advising and making recommendations to the IPM Coordinator and Board of Supervisors. Read more about the IPM Commission, and learn about the Marin Monarch Working Group’s selection as the 2024 IPM Award winner, given annually to organizations that reduce pesticide use in Marin. This website by Our Water Our World also offers helpful ideas for controlling pests using natural methods.
Within Marin, each city or town controls its own pest-management policies in its buildings, parks, and roadside spaces. The city with the strongest anti-pesticide policies is Fairfax, which prohibits the use of all synthetic pesticides in parks, open space parcels, public rights-or-way, and town owned and maintained buildings. Others that have banned glyphosate include Novato, San Rafael, Larkspur, and Mill Valley.
Stafford Lake
Pesticide Free Zone is an active and effective local organization focused on reducing the use of pesticides throughout the county. Established in 1997, and then known as Marin Beyond Pesticides Coalition, the group included 44 Marin organizations and businesses working to change the way people view the use of pesticides. The group’s first objective was to work with the County to reduce the use of pesticides in public spaces and implement an integrated pest management (IPM) strategy. That goal was realized in December 1998 when the Marin County Board of Supervisors passed the IPM Ordinance, which was subsequently revised and adopted in 2010.
The group is currently focused on encouraging the use of IPM in home and school gardens.
Which Marin Nurseries Practice IPM?
Adherence to IPM varies significantly from one nursery to another. The highest adherence can be found in local nurseries that are devoted exclusively to native plants and that have certifications or sustainability programs.
The following are some of the nurseries in Marin that focus on California native plants and neither use pesticides on their stock nor advocate its use for purchased plants.
Home Ground Habitats: 1875 Indian Valley Road, Novato
California Native Plant Nursery: 254 Shoreline Hwy, Mill Valley
O’Donnell’s Fairfax Nursery: 1700 Sir Francis Drake Blvd, Fairfax
Most other independent retail nurseries and conventional garden centers are likely to use parts of IPM but may not always have a firm policy of using chemical pesticides as a last resort.
