Emerald Ash Borer Treatment- Toxic To Bees?

Image Source: Wikipedia

The emerald ash borer, Agrilus planipennis a beetle native to China, Japan and Korea was introduced into North America in the Great Lakes area in the early 1990's and populations were identified in 2002. It is suspected that this beetle was introduced from ash shipping crates. Emerald ash borer beetle larva burrow through the outer bark of ash trees, Fraxinus spp. and into the living cambium tissue.

As the larvae feed on the cambium, they create 'S'-shaped galleries in the wood. The galleries created from a large infestation weaken the ash trees causing canopy thinning and eventually canopy die-back. A secondary symptom is numerous shoots forming around the base of the ash tree.

Current Map of Emerald Ash Borer Range
Source: emeraldashborer.info

As a homeowner living in Minnesota just outside the range of emerald ash borer, I started to research the treatments being offered by local tree care companies. I only have one ash tree on my property and do not plan to treat it but many of the suburban neighborhoods in the Twin Cities were heavily planted with ash trees in the late 1970's and early 1980's. I am reminded when driving through these neighborhoods that planting a diversity of native plant species in your landscape will help with weathering the impacts from invasive species and climate change.

"Systemic insecticides containing the active ingredients imidacloprid, dinotefuran or emamectin benzoate are commonly used to protect ash trees from EAB." (Potential Side Effects of EAB Insecticides) Imidacloprid belongs to the group of neonicotinoid insecticides which has been linked to Colony Collapse Disorder (CCD). Read a recent Xerces Society report here: Are Neonicotinoids Killing Bees? Today, a coalition of bee-keepers have filed a suit against the EPA for failing to suspend the use of neonicotinoid pesticides.

Imidacloprid, sold under the trade names Merit, Xytect, Optrol, ArmorTech, Enforce, Hawk-I, Turfthor, Malice, Premis, Criterion, Hunter, Submerge and Touchstone is typically applied as a soil drench or soil injection annually as a preventative treatment for emerald ash borer. For a homeowner with several ash trees, the cost can be very high. The city of Minneapolis now recommends replacing ash trees on residential properties rather than treating them due to the environmental risks from the treatments including, leaching into the surface or ground water, uptake by other plants visited by pollinators for nectar and pollen and non-target effects on woodpeckers feeding on EAB larvae.

Are your ash trees worth saving or should you be preparing for their replacement? Are the risks of using neonicotinoids too high? Purdue University offers a cost calculator for EAB treatment for homeowners here. Trees with structural defects, poorly sited, or with no historical or aesthetic value should not be treated. Read more guidelines here.

Perhaps our efforts should be focused on the conservation of ash tree species. Volunteers are needed for the collection of ash seeds to help preserve genetic variation and with a long-term goal of the reintroduction of ash trees into affected areas. Find out more information on how you can help collect ash tree seeds.

References:
The Effects of Neonicotinoids on Honey and Bumble Bees.Vera Krischik, Entomology, University of Minnesota.
Chemicals Implicated. BeyondPesticides.org
Blacquiere, T., Smagghe, G., Van Gestel, C. A., & Mommaerts, V. (2012). Neonicotinoids in bees: a review on concentrations, side-effects and risk assessment. Ecotoxicology, 1-20.
Emerald Ash Borer Info