Tuesday, August 28, 2012

Freshwater Jellyfish, Tropical Crickets, and Belding’s Ground Squirrels

Freshwater jellyfish advertised for sale in a pet catalog.

Most of the time we spend on invasive species issues involves legacy programs like gypsy moth, sudden oak death, and giant hogweed. Excluding them from Oregon is a high priority for the Oregon Department of Agriculture (ODA). These are big programs that occur year after year. Smaller issues pop up from time to time, and we deal with them as they arise. Here are three small invasive species stories from my week, each with an odd twist.

I took a hotline call this week from a woman with “jellyfish” in her pond. In my mind, I was thinking it was probably a bryozoan. There was a call about those last week—but that’s another story. I told her I doubted it was really jellyfish, but if she’d send a picture, I’d find someone to identify it. Within an hour, there were jellyfish pictures in my email box. Dr. Mark Systma at Portland State University confirmed it. It turnes out a species of freshwater jellyfish is spreading rapidly around the world.

If you’re wondering how freshwater jellyfish could spread rapidly anywhere, Google “freshwater jellyfish” like I did. Note the sponsored ad for: “Floating jellyfish small (2-pack) $8.99, free shipping on orders over $49!”

My second story has a “Mouse That Roared” theme. This week, I received three permit requests for tropical house cricket, Gryllodes sigillatus. A year ago, the pet food cricket industry was in crisis due to a virus disease wiping out their breeding colonies. See my earlier blog (www.oregoninvasivespecies.blogspot.com/2011/05/cricket-crisis.html). The industry wanted to bring in another species of cricket from Europe. The US Department of Agriculture (USDA) and other states said okay. ODA did not. Our entomologists had concerns about their ability to survive outdoors and compete with native species. So we refused to sign off on USDA permit appications for the new species. Instead, we suggested the tropical house cricket, which is easy to rear, disease resistant, and can’t live outdoors. It took a while, but USDA and the industry have come around to our way of thinking. This mouse that roared is going to have tropical crickets for supper!

Lastly, a colleague and I visited with some farmers in Malheur County and looked at damage to alfalfa fields caused by Belding’s ground squirrels. The squirrels estivate in the summer, so we didn’t see any of them, but there there were plenty of burrows. Every 10 feet or so there was another one. Two different farmers told us you could use up a whole brick of 22 caliber ammunition (500 bullets) shooting ground squirrels from a single spot in a field, then come back the next day and do it again from the same spot! Either they are really poor shots, or there are beaucoup ground squirrels. I think its the latter.

The interesting thing about this to me is that these are not an invasive species. The ground squirrels are acting like an introduced pest without natural natural enemies, but they’re not. Ground squirrels were there before the farms. Their population has just exploded because we’ve planted thousands of acres of succulent ground squirrel food.

It’s a good reminder that though most of our problem pests and weeds are foreigners that have hitchhiked here or were spread by people buying $8.99 two-packs, some are home grown, and there is nobody out there to blame. Stuff happens, and it all makes for one very interesting work week!

Dan Hilburn

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