Wednesday, November 1, 2000

Flea Beetles Have a Great Year Despite Rumors
By Steve Merritt for the MSU News Service

Contact: Steve Merritt (406-433-9440; smerritt@sidney.ars.usda.gov)

SIDNEY, Montana – Leafy spurge flea beetles don’t start rumors, but can be the subject of gossip and hearsay.

This summer, rumors about a flea beetle population crash in North Dakota resulted in the cancellation of field day events, restricted access to healthy and harvestable flea beetle populations, and agency officials contemplating reduced funding for future leafy spurge biocontrol efforts.

Unfortunately, the rumor was "just plain wrong," says Gerry Anderson, an ecologist at the USDA-ARS Northern Plains Agricultural Research Laboratory in Sidney, Montana, and co-principal investigator of the TEAM Leafy Spurge area-wide program.

"Flat out, there was no big, widespread flea beetle population crash this summer," Anderson said. ""The rumor gave the impression that flea beetles weren't doing well, and that's too bad because they're doing great. In fact, there were more flea beetles at more sites this summer than ever before, and we can expect to see even more in the future."

Anderson says he thinks he knows how the rumors started.

"We saw some interesting thing this year – some incredible things, really – and yes, we saw some populations decline in specific, localized areas," Anderson said. "But – and this cannot be over-emphasized – the declines we saw resulted from massive reductions in spurge. The flea beetles were gone, but so was the spurge."

Entomologist Bob Richard, director of the USDA-APHIS Biological Control of Weeds Laboratory in Bozeman, Montana, said the site-specific population declines were classic examples of flea beetles in action.

"The flea beetles are doing exactly what they’re supposed to do," Richard said. "When all the spurge is gone, they'll be gone too – they either move to find more spurge or die."

Unfortunately, the "facts got all mixed up," Anderson said, causing some unnecessary concern about the general well being of flea beetles. But, on a positive note, the rumor stressed that there are lessons to be learned from the summer of 2000.

"The lesson from this summer, and it's a really important one, is that flea beetles cannot be taken for granted," Anderson said. "Never assume that flea beetles will just be there. It's not like it used to be 10 or even five years ago – we now have some incredible flea beetle numbers spread across a wide geographic area, and we can expect to see more site-specific spurge reductions and flea beetle population declines. People need to be prepared."

TEAM Leafy Spurge offers the following tips to prevent site-specific population declines from causing problems for your leafy spurge biocontrol program.

• Don’t miss your opportunity to harvest! "Not utilizing good sites is the most common problem we see," says USDA-APHIS PPQ officer Dave Hirsch, who has conducted field day events for more than a decade. If you can collect several thousand flea beetles from a site, begin harvesting and using the flea beetles to start new release sites. The lesson: Don’t delay!

• Don’t depend on one site. You may have a favorite site, but don't expect it to produce big numbers forever – it can only last so long. As witnessed this summer, spurge infestations can rapidly decline when flea beetles populations reach high numbers, and a population that looks GREAT this year may be gone next year. The lesson: Start new sites every year to protect future harvesting opportunities.

• Where? "We saw many areas this summer where flea beetles had nearly eliminated the spurge and moved to new areas," Hirsch said. These new areas can be surprisingly long distances from the original site, he added, and can provide "unbelievable flea beetle numbers." The lesson: If flea beetles don’t show up where (and when) expected, keep checking and scout surrounding areas.

• When? Although there are average dates to go by, emergence is site-specific and can vary by as much as two weeks. The lesson: If flea beetles don’t show up when (and where) expected, keep checking and scout surrounding areas.

• Monitor your sites. When spurge infestations begin showing signs of rapid thinning due to flea beetle activity, be prepared – the flea beetle population could explode and take out the spurge in a single season. "We’re now at a point where extremely rapid decreases in spurge infestations and subsequent flea beetle population declines will be more common," Richard said. The lesson: Monitor your sites and harvest accordingly to prevent the loss of populations that could be used to start new sites.

• Develop more partnerships! Private landowners have established thousands of new sites the past few years, but public agencies continue to provide most of the access to land and flea beetles for field day/distribution activities. Landowners who obtain beetles at field day events need to understand that they are getting "seeds" that need to be planted, managed and shared, Hirsch said. "Developing partnerships and working together to help maintain the resource is absolutely crucial," Hirsch said. "We need more landowners like Leon Rummel of Gladstone and Ken Quam of Tolna that provide their neighbors with access to flea beetles." The lesson: Share your flea beetles!

The bottom line, Richard said, is planning.

"It really shouldn’t be surprising that flea beetles will take out a patch of spurge then move on the greener pastures because that’s what they’re supposed to do," Richard said. "Managing your flea beetles is the key – if you monitor your sites and move your flea beetles around to start new sites, you shouldn’t have any problems when flea beetles wipe out a site."

TEAM Leafy Spurge is a five-year research and demonstration project funded and led by the USDA-ARS in partnership with the USDA-Animal & Plant Health Inspection Service. It’s goal is providing landowners and land managers with proven leafy spurge control techniques based on IPM strategies.

TEAM participants include the National Park Service, U.S. Geological Service, U.S. Forest Service, Bureau of Land Management, Bureau of Reclamation, Bureau of Indian Affairs, land grant universities (including Montana State University, North Dakota State University, South Dakota State University and the University of Wyoming), cooperative Extension Services, county weed supervisors, and private ranchers and landowners.


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