New research published in the journal Nature in July 2014 suggests that imidacloprid may negatively impact birds, in addition to insect pollinators (6). Led by Eelke Jongejans from the Radboud University Nijmegen in the Netherlands, the researchers hypothesized that imidacloprid has a negative impact on populations of birds that eat insects. Specifically, they asked whether there was a significant correlation between the concentration of imidacloprid in water sources and bird populations in those areas.
Due to the connection between neonicotinoid exposure and pollinator health, the European Commission issued a two-year ban on specific uses of three different neonicotinoids–including imidacloprid (5). The ban includes seed and foliar, or leaf, treatments of crops including cereals, corn and sunflowers. The dust kicked up from planting imidacloprid-treated seeds and the chemically-contaminated nectar and pollen were cited as exposure routes for bees. However, the extent of imidacloprid’s environmental impact remains unclear. Are other organisms, beyond insects, affected?
The second dataset came from the Dutch Pesticide Atlas, a database of measurements from routine monitoring of over 700 chemicals, including imidacloprid, in surface waters throughout the Netherlands. From these data, they could make a map of the average imidacloprid concentration measured in different locations in the time period from 2003-2009.
Despite its selective and acute toxicity for the insects that farmers would like to rid from their crops, imidacloprid use has been linked to several negative environmental impacts. The driving factors for imidacloprid’s environmental effects are its physical characteristics (Figure 1). Imidacloprid has a polar, or non-greasy, structure, making it very soluble in water. This physical characteristic allows the chemical to be distributed throughout the tissue of seed-treated plants via the plant vasculature. Thus, a flowering plant seed-treated with imidacloprid will contain the chemical in its pollen. Furthermore, imidacloprid that isn’t taken up by plants will be carried in the water run-off from the field. In addition to its water solubility, imidacloprid has a half-life in soils greater than 1000 days, meaning that after nearly three years, half of the initial concentration of imidacloprid will still remain in a given area (2). The long lifetime and water solubility of imidacloprid mean that it can be widely dispersed from areas where it was first applied and it can accumulate in soils and water over time. Imidacloprid’s physical traits have negative and unintended consequences for organisms not targeted by the insecticide, including pollinators like bees and, as new research suggests, even birds.
As children, we learn about one of Nature’s most beautiful and ingenious inventions: the seed. We learn that the coat of a seed provides both protection and nutrition for the fledging plant inside. We learn later in life about the less beautiful truth of commercial seeds. Our modern-day seeds are often covered in a layer of synthetic chemicals, designed to protect the plant from pests like weeds and insects. While these chemicals can increase the efficiency of farming, there are negative environmental consequences of widespread and intensive use of herbicides and pesticides, some of which are just being elucidated. The most common seed treatments are chemicals from a family of compounds called neonicotinoids. As the name implies, these compounds are structurally related to nicotine, the naturally occurring alkaloid stimulant found in tobacco leaves. Seeds from an array of crops, including cereals, corn, sugar beets, rice and cotton, are treated with neonicotinoids, which serve as highly effective insecticides.
Opening the lines of communication between research scientists and the wider community
In the 2014 Nature paper from Jongejans and co-workers, the concentration of imidacloprid in surface water was shown to be negatively associated with insectivorous bird populations in the Netherlands.
The researchers suggest that the association of bird population decline and imidacloprid could arise from the simple fact that intensive use of imidacloprid on farmlands will deplete insect populations, and insect-eating birds rely on these bugs for food. While birds may not be killed directly by consumption of imidacloprid, decimation of their resources will affect their ability to reproduce and feed their young. The researchers emphasize that more studies should be done on the trophic, or food-related, interactions between pesticides and animals. In conclusion, this study shows that there is a significant correlation, or association, between the concentration of imidacloprid in water and the populations of birds in these same areas, but more studies are needed to pinpoint the direct causes for these effects on bird populations.
Even the plants we do have listed below are poisonous in varying levels and in different ways. Some may be toxic if you ingest the leaves, while others are toxic if you eat the roots. Some may simply make you very sick if you eat the poinsonous parts while others can cause death. None of the plants we have listed are deadly poisonous simply by touch, though a few can leave a nasty rash if you touch the leaves or sap with your bare skin. That being said, here are some toxic garden plants that will fit right in, some well-known and others with an interesting history:
As with any garden design, there are certain to be various ways to create a toxic plant garden, and this is what makes gardening so fun. No one garden is exactly the same. Feel free to put your own spin on it, but just to keep things safe, it never hurts to heed a few helpful tips along the way. So as you’re creating a poison garden in your landscape, you may want to take these ideas into consideration:
Now that you have a few ideas to help get you started, it’s time to choose some plants for the poison garden theme. Since, in reality, it could be argued that most plants in some way or other have toxic properties, it would be impossible to name them all.
Creating a poison garden need not be so morbidly named or crafted. Make it your own, like you would for a recipe. Put your favorite “toxic” herbs in a corner of the landscape … fenced off from other more traditional plants. Showcase old-world specimens with a long history surrounded in lore. Choose commonly seen plants once found in a witch’s garden. Likewise, you might want to stick with everyday toxic garden plants. Yes, there are more than you might think. In fact, many commonly grown plants are actually poisonous in some fashion.
How to Create a Poison Garden
If you’ve read my book The Garden Crypt, then you know all about my fondness towards unusual things in the garden. Well, creating a poison garden is something that’s right up my alley. Before some of you get alarmed, let me make one thing clear – this type of garden is NOT to be used for malicious purposes and by all means, if you have pets or small children, DO NOT attempt to grow a toxic plant garden! With that said, those who are interested in this unique garden space, read on to learn more.
Disclaimer: The contents of this article is for educational and gardening purposes only. Before adding any of these plants to a garden, research them carefully and ALWAYS handle toxic plants appropriately. NEVER plant these in areas frequented by animals or children.