The emerald ash borer is a small insect that damages ash trees by boring into the sap vessels of the tree. In its native habitat of East Asia, the trees it infests can cope with its attacks – there is a natural balance between the pest and its food plant. However, in 2002, the emerald ash borer was discovered in North America, where it started to wreak havoc on the native species of ash to such an extent that by 2012, over 100 million ash trees in North America had been killed and felled.
The damage the emerald ash borer does is severe and usually fatal, and there are an estimated 7.5 billion ash trees vulnerable to attack in North America. As you can imagine, the control of the pest is a major focus of research by forest scientists and huge resources are being deployed to find a solution to this deadly insect.
Recently, a team of forest scientists, led by Dr. Geoffrey Donovan from the US Department of Agriculture Forest Service, published a research paper about the emerald ash borer. Nothing unusual in that, except that the paper was published in the American Journal of Preventive Medicine. What is the connection between a small tree-eating bug and human health?
The answer is surprising. It seems as if there is a very strong statistical relationship between the progress of the ash borer across the USA with increases in mortality due to cardiovascular and lower-respiratory-tract illness. The relationship is so strong, and the data so powerful, that the researchers believe that as many as 21,000 additional deaths in 15 states are associated with the effects of emerald ash borer. Not only that, but there seems to be a disproportionate effect in wealthier neighbourhoods.
So, are emerald ash borers poisoning the environment? The answer to that is an emphatic “no.” The deaths seem to be associated with the destruction of the trees in the environment. The removal of so many trees in some areas has removed the natural health benefits associated with having trees in the environment. Wealthier neighbourhoods tend to have more trees, so the removal of those trees magnifies the effect of their loss.
Donovan and his colleagues suggest that the removal of the trees has resulted in the removal of the ability of trees to reduce stress, blood pressure, regulate temperature and even encourage physical activity. This disconnection with nature is becoming an increasingly well-understood phenomenon. Whilst it will take generations for the ash tree population to recover, we can all do our bit to bring a bit of nature back to our environments by planting trees, tending our gardens and making our built environment a bit greener – trees in and around our buildings really are essential for our well-being.
 The relationship between trees and human health: evidence from the spread of the emerald ash borer.
By Geoffrey H. Donovan, PhD, David T. Butry, PhD, Yvonne L. Michael, ScD, Jeffrey P. Prestemon, PhD, Andrew M. Liebhold, PhD, Demetrios Gatziolis, PhD, Megan Y. Mao. In The American Journal of Preventive Medicine, Volume 44, Issue 2, Pages 139-145, February 2013 (Link)
To learn more about humanity’s innate need for nature, explore our “Do You Feel a Need for Nature…at Work?” Infographic.