Written by Beth Lavenz
Back in March, Kristine Nemec of the Tallgrass Prairie Center gave a presentation about planting a small prairie or butterfly garden in your backyard. Students were fascinated by her information and how easy it seemed until we began talking about plants. Kristine talked about where she purchases her plants from and mentioned that many big box stores sell plants that have been treated with nicotinoids already. She tends to avoid these stores for plant purchases as she believes in limiting the number of pesticides that her gardens receive and rightfully so. When it comes to using pesticides, those troublesome garden insects are not the only organisms being removed. Non-target organisms can also be affected and may include natural predators for invasive bugs and garden visitors like bees. Many plants we purchase today have already been treated with pesticides and may be impacting our gardens without us knowing about it.
While “low impact” pesticides exist, some gardeners and activists believe that even a low impact on the environment can be too much. However, the argument for or against pesticides is for another day. Long-time gardeners have tailored their garden practices to include a number of natural and commercial applications however the impact of one group of pesticides in particular, neonicotinoids, is beginning to get a lot of attention.
Neonicotinoids are pesticides that are chemically similar to nicotine. Companies began developing neonicotinoids in the early 80’s in response to pest resistance, especially in agricultural and crop settings and the pesticide became widely available in the 90’s. Hailed as the latest and greatest, the pesticide was promoted for its low toxicity to other insects and animals, however, the research is divided in regards to the effect of this pesticide on the environment. There are seven neonicotinoids used in a variety of garden products available today. You can tell if a product uses a neonicotinoid if it has any of the following as ingredients: acetamiprid, clothianidin, imidacloprid, nitenpyram, nithiazine, thiacloprid, or thiamethoxam.
According to the Xerces Society for Invertebrate Conservation, neonicotinoids severely impact the health of non-target insects, especially bees. Once applied, the pesticide is absorbed through the soil and through testing, the plants attempting to take nutrients from the soil have been found to transfer some of the pesticides to the pollen and nectar of the plant. This increases the chance that non-target insects, like bees, will receive secondary exposure through the pollen rather than primary exposure, such as being sprayed with the pesticide. Due to the difference in the size of bees vs the plant they take pollen from, smaller amounts of exposure can easily impact the health of bees. Another concern focuses on the length of time that neonicotinoids remain in the soil and the amount that remains after multiple applications. Another issue related to the use of neonicotinoids include the application process which can transfer the pesticide to other plants through the air and water.
Neonicotinoids work by paralyzing insects and blocking the messages sent to the insects’ nervous system. A study done by the Xerces Society for Invertebrate Conservation found that four out of the seven neonicotinoids were found to be highly toxic while the other three were found to be moderately toxic to honey bees. Incorrect application procedures can cause drift from the target plant to others in the area or be carried along in water and sent downstream affecting more than just the originally treated plant. Preventative applications often found in agricultural settings change the need for previous biological predators which can impact the variety of insects, both good and bad, visiting your garden.
Ultimately neonicotinoids can be used as an absolute last resort to pest management but the best option for gardeners looking to limit their impact on the diversity of insects in the garden would be to prepare an integrated pest management plan and use other options such as crop rotation and neem extract to fight against pests in the garden. By learning more about the effects of the products we use in our gardens we can help to limit the amount of exposure vulnerable populations, such as bees receive to these deadly pesticides.
References & Resources to learn more:
http://ento.psu.edu/publications/are-neonicotinoids-killing-bees (The infographic comes from this resource and can be found on page 17)