Researchers gaining ground in battle with alfalfa snout beetle

Researchers said last week they may be gaining the upper hand against a tiny green invader that has plagued north country farmers for more than a century.

Their weapons: old-fashioned selective breeding and millions of carnivorous worms.

The alfalfa snout beetle, an invasive species that likely came to Oswego in boat ballasts in the 19th century, has marched through the north country ever since. The insects lays eggs at the root of alfalfa plants. Larvae feed on plant roots, severely damaging the vital forage and rotation crop critical to dairy and other livestock farmers.

"We've had alfalfa snout beetles for decades," said Douglas W. Shelmidine, co-owner of Sheland Farms, Ellisburg. "They will wipe out a field in a couple of years."

That decreases a field's profitability because alfalfa seeds are expensive and, normally, a crop has higher quality after the first few years. Farmers try to get multiple years out of one stand of alfalfa before switching to corn or other crops.

Elson J. Shields, professor of entomology at Cornell University, Ithaca, and Julie L. Hansen, senior research associate in the department of plant breeding at Cornell, updated farmers last week on progress toward biological control and alfalfa varieties resistant to the beetles. Their presentations were given during Cornell Cooperative Extension Crop Congresses, which traveled across Northern New York.

"The long-term maintenance will be resistant varieties," Mr. Shields said. "We'll knock the population down through biocontrol."

Biocontrol is done through insect-killing ringworms, also known as entomopathogenic nematodes. Mr. Shields spread two native nematode species on John E. Peck's farm in Champion beginning well over a decade ago.

"It's been remarkable what it's done," Mr. Peck said Thursday. "The beetles are down by a huge percentage."

The nematodes have spread on their own and are not causing problems for other native species.

"Some may have moved around with the equipment," Mr. Peck said. "But some fields have them that we haven't touched."

Mr. Shields agreed the nematodes have been extremely effective in decimating the alfalfa snout beetle population. He said his research team successfully spread nematodes on 36 fields in the past year. They reduced worm-rearing cost by 350 percent, cut typical spreading time from eight to two hours and trimmed the cost of materials needed to apply the worms in the field.

Each inoculation requires about 100 million nematodes.

This year, Mr. Shields said, the team should spread nematodes on another 36 fields, expand into Clinton and Essex counties and begin work on possibilities for commercial application. They are developing a pilot program for 2010 that would allow farmers to grow their own nematodes.

Another aspect the of the nematode research is how well the worms survive after rotating a field from alfalfa to another crop and then back to alfalfa.

"We don't know how it will persist across a rotation," Mr. Shields said. "We're beginning to look at that."

The second prong in the attack against the snout beetle is the development of an alfalfa species resistant to the larvaes' feeding damage.

Ms. Hansen is part of a team that picks up 20,000 beetles every May as they march across fields and roads. The eggs they produce are put in pots with alfalfa plants. Those plants that survive the feeding of alfalfa snout beetles are re-potted. About 30,000 plants each year are planted, tested and the surviving plants are crossbred.

"We're making progress," Ms. Hansen said.

Damage to alfalfa plants is rated from one (no or minor damage) to five (severe root damage and dead plants). After three rounds of crossbreeding, the surviving plants have improved from a 3.5 to 2.3 in the damage shown.

A research plot of several varieties of resistant alfalfa was planted on Mr. Shelmidine's farm in Ellisburg last year. It will be tested by larvae this summer.

"In the fall, we'll evaluate the breeds," Ms. Hansen said.

If one stands out as showing light damage, it could be used for seed production. But it would be three years before enough seed is available to market.

"It's unlikely the first variety released will have the best possible resistance and highest yield," she said. "It will probably be three or four generations to have the greatest resistance and yield."