At a recent conference for the International Society of Arboriculture, we had the opportunity to hear a special speaker, Richard Cowles, from the Connecticut Agricultural Experiment Station of Windsor, CT. Mr. Cowles spoke on the topic of using neonicotinoids in landscaping and their affects on honey bee populations. The following text represents conclusions from his studies and observations. Please consider his findings with an open mind.
What are Neonicotinoids?
Neonicotinoids are systemic insecticides that are chemically similar to nicotine. These insecticides are not toxic to humans, when handling them, but are highly toxic to the nerves of insects – they interact with insects’ nerves the same way nicotine does in humans. For the targeted pests, this result is positive; however, there is much controversy regarding whether or not these insecticides are harming the bee population.
Systemic insecticides are transported through a tree or plant’s sap. The applicator applies the insecticide in one area of the plant, and the sap moves it to other parts of the tree or plant. Neonicotinoids move only upward (product examples include: Orthene, Merit, Tristar, Safari). Systemic insecticides are incredibly useful because the chemical moves throughout the entire tree or plant with a single, local application. The mobility varies among plant species and tissues. Application method (i.e. folair, soil injection, trunk injection, basal bark sprays) determines effectiveness. Sucking insects are easily targeted with this method. There is also a multi-year effectiveness due to storage of the chemical within the plant (concentrations vary between tissues of treated plants); the chemical remobilizes to new growth in subsequent years. This minimizes its affect on the environment if used with discretion.
Imidaclorid Hemlock Wooly Adelgid – treatments are effective for five years from single soil drench application. Chemical can actually be detected in hemlock for nine years.
There are 600+ species of bees native to North America. It is commonly said that neonicotinoids can:
- Kill bees outright (high exposure),
- Interfere with bees’ foraging behavior,
- Create maladaptive behaviors (with low exposure to chemical),
- Create colony collapse disorder (most bees move from their hive).
These are four very common and widely accepted misconceptions. These misconceptions originated from flawed studies from groups such as Friends of Earth. These studies involved large-dose application practices and tested leaves and parts of flowers that bees don’t come into contact with. While the chemical was present in large quantities on these parts of the plants, there was no way for bees to be poisoned by the parts with the chemical. Nonetheless, groups still published that “the chemical is there, and the bees will be poisoned.” Unfortunately, once the public hears and accepts a negative idea, it is practically impossible to change their mind – no matter how much evidence is presented to disprove what they have decided.
What Is Causing the Bee Decline?
When the majority of worker bees leave a hive, leaving behind the queen, it is known as colony collapse disorder. CCD first occurred long before neonics were in use. Records and research show that Isle of Wight Disease, a disease that causes CCD, occurred as early as 1904 long before pesticides were in use.
A recent study by Josephine Johnson, Ph.D., further demonstrates that neonicotinoids are not the cause for CCD. Her study took place in NYC. She took bee hives and placed them in and around trees being actively treated with neonics, targeting the Asian Longhorn Beetle. The study showed no insecticide in hives or in the bees. Ms. Johnson was trying to prove that neonics caused CCD. Instead, all her results indicated that the chemical was not in the hives as she thought it would be.
Research has shown strong evidence that a disease (virus) is responsible for CCD. Countries that ban the use of neonics still have CCD; however, Australia uses neonics but has no CCD. These findings lead us to believe that viral and other diseases cause CCD.
So What‘s All The Hype About?
All evidence points clearly to viruses and diseases as the primary culprits for the decline of the bee population. But, you have, for lack of a better term, quaks and shammers who continue to pretend to do legitimate research and mold studies to point to neonics. With this being said, it is still possible to significantly harm bees with neonics.
Neonicotinoid pesticides are readily available to the public who are generally inexperienced and uneducated with regards to systemic pesticide application and best practices. Often, even those who are expected to be educated and experienced are not and make mistakes that do cause great harm to bees (see Wilsonville, Oregon’s Target Store mishap). When used improperly, neonics can be very toxic to bees.
Acetamiprid is the safest neonicotinoid. Tri Star is also much less toxic to bees. In landscape/homeowner situations, chemicals are often over applied so that bees are poisoned. It is very important that applicators read and follow labels and dosage rates according to instructions. In some cases dosage rates need to be adjusted to protect pollinators. Never apply neonics to linden trees as their pollen is already toxic to bees. Don’t apply residual neonics systemically to trees highly attractive to bees. For easy-to-kill pests, only re-apply systemic pesticides once pest populations start to increase again. If you over apply systemic pesticides, you:
- Jeopardize non-target pollinators,
- Induce spider mite outbreaks,
- Apply more pesticides to environment than is justified.
Only really hard-to-kill pests require treatment each year – i.e. Asian Long Horn Beetle and Emerald Ash Borer.
North Branch Landscape has licensed pesticide applicators, licensed in both Vermont and Massachusetts. You can have confidence in our knowledge and expertise as we use best practices in pesticide application, protecting your landscape from pests and your pollinators from harm.
This blog post is based on a lecture by Richard Cowles (Researcher) from The Connecticut Agricultural Experiment Station of Windsor, CT. Richard Cowles is an expert in the area of biology and entomology. He is experienced in the uses of conventional and new insecticides for the management of nursery, turf, landscape, and small fruit pests.