distribute throughout the tree, depending on the tree’s size and health and on weather conditions.
Can insecticide be used to treat infested trees instead of removing them?
Unfortunately, no. Variability in treatments, weather conditions, and overall tree health can result in uneven insecticide distribution within a tree and prevent the insecticide from killing all ALB in an infested tree. Also, the insecticide is not effective against the later larval stages that spend most of their time inside the heartwood of the tree where treatment will not reach them. These larvae can continue to grow inside the treated tree, develop, and still emerge as adult beetles. All infested trees must be removed because that is the most effective way to completely eliminate the beetle. Even treated trees are removed and destroyed if they are later found to be infested.
What research has been done on the use of imidacloprid to control ALB?
USDA and Chinese researchers conducted lab and field tests in China and the United States. Out of multiple insecticides tested, imidacloprid proved to be most effective. Specifically, the testing indicated that imidacloprid was effective against adult beetles as they feed on small twigs and against young larvae as they feed beneath the bark. Imidacloprid has been very well studied for other uses as well, with many articles published in international, peer-reviewed scientific journals.
How will these treatments affect the environment?
Imidacloprid treatments are applied per product label requirements designed to protect human health and the environment. The precise placement of injection treatments and the measures used to ensure precision during applications help prevent potentially adverse environmental effects. Also, imidacloprid residues are limited to the treated tree and its root area. The degradation process, or natural breakdown of these residues, further minimizes any impact on the environment.
Can imidacloprid harm bees? And are there alternatives?
EPA issued a preliminary risk assessment for imidacloprid suggesting that some aerial applications may harm bees. The risk assessment did not show any adverse effects to bees from tree trunk or soil injections. USDA conducted a study in Massachusetts and New York that demonstrated applications made to control ALB do not expose bees to harmful levels of imidacloprid. We continue to evaluate alternatives, but at this time none are as effective against ALB as imidacloprid.
For More Information
To learn more about imidacloprid, go to pubchem.ncbi.nlm.nih.gov/compound/imidacloprid.
For more information on ALB, visit www.aphis.usda.gov/pests-diseases/alb.
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PPQ-22-004 | Issued March 2022
