Issue 2, May 4, 2015
Insecticides in Bedding Plants
There have been concerns about the use of neonicotinoid insecticides, particularly imidacloprid, clothianidin, thiamethoxam, and dinotefuran, in bedding plants purchased at garden centers, and their effects on honey bees and other pollinating insects. Much of this interest was generated by a report by Friends of the Earth of analyses conducted on bedding plants being sold in garden centers in spring 2013 and published later that year. A review article I wrote is at http://web.extension.illinois.edu/ipr/i8739_829.html#124754. This was followed by a more extensive study, Gardeners Beware 2014, Bee-Toxic Pesticides Found in "Bee-Friendly" Plants sold at Garden Centers Across the U.S. and Canada that can be accessed at http://libcloud.s3.amazonaws.com/93/3a/3/4738/GardenersBewareReport_2014.pdf.
Earlier this year, Lowe's announced that they will phase out sales of neonicotinoid insecticides by 2019 as they identify replacement insecticides. Many garden centers are requiring that growers label bedding plants as to whether neonicotinoids insecticides have been used on them.
AmericanHort, Society of American Florists, Horticultural Research Institute, and American Floral Endowment issued a statement in response to Lowe's position on neonicotinoid insecticides as follows.
April 9, 2015 (Washington, D.C.) - As professional horticulturists, we grow trees, plants and flowers, and healthy trees, plants and flowers are critically important to healthy bees and healthy bee habitats. Pollinator health is a highly complex issue, and we recognize that there many factors that can affect bee health. Although the improper use of pesticides can harm bees, a growing number of credible independent studies indicate that neonicotinoids, when used as directed, are not the cause of widespread bee health issues.
Consumers want plants that are healthy, beautiful and pest-free, and neonicotinoids have proven to be among the most effective pest management tools available. Neonicotinoids also are among the safest products we have for both our employees and the environment.
Lowe's position is surprising, considering the most recent and positive reports on the state of honeybee health (NASS honey report) and recent peer reviewed research. This is an issue for which sound science must take priority. Plant growers are experts on how to produce healthy plants. We embrace the challenge of protecting bee and pollinator health and the opportunity to be part of the solution. We will continue to fund important research on the health of bees, and guide horticulture on safe and responsible pest management. Horticulture will look to the best science to guide our efforts. For additional information on what horticulture needs to know about pollinator health, view our video at http://bit.ly/ProtectingPollinatorsVideo.
The full statement is at http://files.ctctcdn.com/cfdf4ef7001/3f2a086b-d1bc-417e-89c7-e6f0d79e4ea3.pdf.
There are numerous research studies that show links between neonicotinoid insecticides and other pesticides with honey bee and other pollinator declines. There are also numerous studies that show links of other factors with these declines. Perhaps the joint EPA and USDA report on pollinator decline issued in May 2013 is the most comprehensive. My review article of that report is at http://web.extension.illinois.edu/ipr/i8627_829.html#123485.
Honey bee worker.
It is not possible to prove that neonicotinoid insecticides in bedding plants and those used on home gardens and landscapes are not major factors in honey bee and other pollinator declines. It is impossible to prove any negative. However, various studies and reports indicate that these insecticides probably play only a minor role in these declines.
Many experts feel that besides relatively low levels of insecticides in the pollen and nectar of treated plants, there is a dilution effect by non-treated plants that are visited in the landscape. This is tempered by recent research showing a preference in honey bees and bumblebees to neonicotinoid-treated plants (http://www.nature.com/nature/journal/vaop/ncurrent/full/nature14414.html#close). Honey bees and bumblebees have previously been shown to have a preference for nicotine, so this preference for neonicotinoids is not a complete surprise.
The European Commission's two-year moratorium on neonicotinoid insecticide use on flowering crops ends at the end of 2015. The resulting analyses and report should be useful in understanding the situation. France stopped the use of neonicotinoid insecticides in 1999 and still has honey bee colony collapse disorder. A recent report states that Australia does not have colony collapse disorder and uses neonicotinoid insecticides, but does not have varroa mite. Varroa mite is a debilitating pest of honey bees that also transmits several viral diseases to honey bees.
University of Illinois Extension continues to recommend the use of neonicotinoid insecticides in controlling insect pests. We will continue to do so as long as their use is supported by research showing they are effective in controlling pests while presenting acceptable risks to human health and the environment, including pollinators. The Illinois Commercial Landscape and Turfgrass Pest Management Handbook also recommends other insecticides for control for those pests where neonicotinoids are recommended except for two insects. We now also recommend the use of emamectin benzoate to control those two pests, bronze birch borer and flatheaded appletree borer. We recommend the application of imidacloprid and dinotefuran to control emerald ash borer after three-quarter leaf expansion to avoid potential ash pollen contamination. (Phil Nixon)
Author:
Phil Nixon