Agroregeneration: Woodpecker Populations Respond To The Emerald Ash Borer Infestation

From the parasitic flies that prey on fire ants to fungal parasites that kill tent caterpillars and beyond, a pattern is emerging of ecological responses to invasive species and infestations. When given the opportunity, nature is capable of balancing systems which seem hopelessly unmanageable from an anthropogenic standpoint. Allowing nature to correct its own issues is generally the most pragmatic solution to these types of problems. The traditional slash, burn and spray techniques are becoming a thing of the past, as they should be.

The emerald ash borer is an exotic beetle whose larvae feed on the inner cambium layer of ash trees. They can effectively girdle a tree, cutting off the flow of moisture and nutrients with its roots. The infestation began in Michigan and has spread at an astonishing rate. It has spread far beyond Michigan and any attempts to control it have met with failure. However, a pattern of increased woodpecker populations in the areas where the beetle populations are highest. This makes perfect sense since the larvae are perfectly edible and nutritious. Increasing numbers of these birds are beginning to suppress beetle populations.

Four species of birds have been noted. The red bellied woodpecker and the white breasted nuthatch (a bark gleaning species) showed population increases very early on. More recently in 2009 both the downy and hairy woodpeckers have started to show population increases as well. Since not one, but four species are showing increased numbers, its quite apparent that a robust ecological response is developing. The emerald ash borer shows great promise as an important food species for these bird species in the future.

the downy woodpecker, hairy woodpecker, red-bellied woodpecker – as well as the white-breasted nuthatch, a common bark-gleaning species that is also a potential predator of EAB.

Read more at: http://phys.org/news/2013-08-woodpecker-populations-linked-feasting-emerald.html#jCp

It remains to be seen if this will be effective enough to allow recovery in devastated forests, but it does provide a measure of hope. Additionally, parasitic wasps and fungal pathogens which prey on the emerald ash borer have been released by the U.S. Department of agriculture and have managed to become established in the wild. Perhaps this multi-pronged approach will be enough to bring the beetle numbers down to manageable levels. This is yet another example of how a biology-based, holistic approach is generally far more effective than anything else.

My main concern is not the increased bird populations, but the release of non-endemic parasites and biological controls, which can have unintended consequences. If the parasitic wasp makes the jump to utilizing native beetles, than this could cause more problems than it solves. In the case of the kudzu bug, the pest species was able to make the jump from kudzu to soybean. There is no reason to think that parasitic wasps or fungus are not capable of similar adaptations. It remains to see how this is going to play out.

http://phys.org/news/2013-08-woodpecker-populations-linked-feasting-emerald.html
http://www.sciencedaily.com/releases/2011/04/110426111415.htm
http://phys.org/news/2013-08-tree-killing-insect-emerald-ash-borer.html

See some of our previous entries on similar subjects:

Mutualism Is More Than Two Species Working Together
Kudzu Bug Jumps Ship And Invades Soybean Fields
Invasive Crab Species Returns Balance To Marsh Ecosystem
Gypsy Moth Problem Beginning To Resolve Itself

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Thursday, August 8, 2013

Woodpecker Populations Respond To The Emerald Ash Borer Infestation

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