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Old 08-29-2011, 12:23 AM   #1
Fox
 
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Default Hyles euphorbiae - Leafy Spurge Hawkmoth

Found a new caterpillar for me today - Hayles euphorbiae (Leafy Spurge Hawkmoth).

The leafy spurge hawkmoth was introduced to the US and Canada in the 60's, 70's and 80's as a biological control agent for leafy spurge (Euphorbia esula). Unfortunately, it seems to have little effect on leafy spurge populations.
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H. euphorbiae larvae defoliate leafy spurge plants, but this damage seems to have little or no impact on spurge populations. In addition, hawk moth populations generally remain low in an area, due to predation and disease. Thus, H. euphorbiae plays only a very minor role in leafy spurge biological control.
Hyles euphorbiae

Leafy spurge is one of those plants that has a large root system and destruction of the above ground part of the plant seems to have only limited effect. The seed is reported to remain viable for 7 years, so once it goes to seed it's seven years of vigilance to have any hope of getting rid of it. The only effective control that I know of is a systemic herbicide that kills the root of the plant.

Euphorbia* esula: UW-Stevens Point Freckmann Herbarium: Plant Details Page

The plant is toxic to cattle. Ironically, this plant has been spread in the US as a contaminant in hay. If you use hay for anything make sure your source is leafy spurge free. I have been battling this plant for many years; it's definitely something that you want to avoid.
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Hyles euphorbiae - Leafy Spurge Hawkmoth-leafy_spurge_hawkmoth_1.jpg   Hyles euphorbiae - Leafy Spurge Hawkmoth-leafy_spurge_hawkmoth_2.jpg   Hyles euphorbiae - Leafy Spurge Hawkmoth-leafy_spurge_hawkmoth_3.jpg  
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Old 08-29-2011, 05:55 AM   #2
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Leafy spurge is a serious rangeland problem in parts of ND where my brother farms. Release of flea beetles (Coleoptera: Chrysomelidae) in the genus Aphthona appears to be much more successful at controlling this weed than the hawkmoth larvae- see Biological Control of Leafy Spurge: An Emerging Success Story. I hope the days of herbicide spraying by helicopter are numbered.
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Last edited by suunto; 08-29-2011 at 01:16 PM. Reason: Corrected word spacing
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Old 08-29-2011, 10:48 AM   #3
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Thanks for posting the link to that very interesting article. I applaud the authors efforts to broaden the perspective on weed management, invasive species and biological control.

I have to admit that I have always been a bit leery of biological controls. I suspect that the early failures have biased my perspective. Today's screening procedures and predeployment protocols would have prevented a lot of those mistakes, but I'm still a little apprehensive when non-native organisms are introduced into an ecosystem. Do we really know enough about the long term outcome, or are we just rolling the dice with our 'latest best guess'? Not that mass deployment of pesticides is a better alternative. I often think pesticides are a part of the human addiction to instant gratification.

I was delighted to see that these flea beetles attack the root system. It gives me hope that there is a much more comprehensive and thoughtful approach to applying biological controls. Trying to control leafy spurge without attacking the root system seemed to me an exercise in futility.

The authors conclude their Ecological Success section with:
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Notice that this definition does not deal with returning the system to some preconceived notion of health and it ignores issues such as maximizing biodiversity or preserving threatened and endangered species. These are important issues that must be addressed, but are probably more appropriately dealt with in the context of post-control rehabilitation.
I think broadening their ecological success definition to include ecosystem health and biodiversity would enhance their overall perspective on weed management and biological controls. It should also bolster their economic argument by bringing in the value/cost of ecosystem services.

(In rereading my post it seems somewhat negative in tone. It's not meant to be. The article really uplifted my spirits. It's great to see perspectives like this making the rounds in the scientific community.)
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