Friday Beetle Blogging: Colorado Potato Beetle

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Leptinotarsa decemlineata

Urbana, Illinois

Meet the Colorado Potato Beetle.

If I had to make a list of ten insects all people should know, I'd probably put this one on it. Leptinotarsa decemlineata is a walking case study in evolutionary ecology.

Anyone with a potato patch will recognize this large, pin-striped beetle as a particularly voracious consumer of potato leaves. And that's true- the insect is a major agricultural pest. But it has only been eating potato plants for 150 years or so. Before that, L. decemlineata was an obscure insect found in the mountains of western North America where it fed on native Solanaceae that no one cared about.

When European settlers pushed west in the 1840's with their newly-planted potato fields, a world of culinary possibilities opened up for this native beetle. A few gave the novel plant a try and never looked back. The population exploded and rapidly spread eastward across the continent. The beetles even reached Eurasia, too. It's a textbook case of an evolutionary host-switch.

The colorado potato beetle evolves in other ways, too. Leptinotarsa decemlineata has become the poster child for pesticide resistance, and its various populations developed resistant to more agrochemicals than any other insect species. Organophosphates? Carbamates? Pyrethroids? No problem- thanks to a prolific life cycle and indiscriminate pesticide application, this beetle can now detoxify all of them.

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photo details: Canon EOS 7D camera

Canon f2.8 100mm macro lens

ISO 100, f/8 (top) f/13 (bottom), 1/160sec

indirect strobe

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I had a few in my potato patch this year but a disease took my plants out before they could do any real damage.

Years ago my dad grew loads of potatoes. Dad bought me a toy insect house and I guess I became an organic way of controlling the problem. I had over 50 at one point all in this little mesh prison.

By MrILoveTheAnts (not verified) on 02 Jul 2010 #permalink

They are such handsome beetles! But come on, make the list of 10 insects everybody should know, are they all agricultural pests?

The @£&$X beetles made it to Sweden in the seventies, and together with nematodes that have invaded northern Scandinavia as the winters grew milder now make life miserable for potato farmers.

We need to come up with a better beetle-eating predator. Canadian geese (themselves an invasive species) are good at eating the invasive Spanish snails (or "killer snails" as we call them here). Maybe a little GM might make them target food with the characteristic pattern of the Colorado beetle? :)

By Birger Johansson (not verified) on 04 Jul 2010 #permalink

Dont their larvae cover themselves with crap?

My thesis project! Mr. Mom: no, although 3rd-instar larvae do regurgitate bubbles of intestinal contents.