Did Predatory Pests Survive the ‘Polar Vortex’ in the Pinelands?

Sizing Up the Cold’s Effect on Ticks and Tree-Eating Pine Beetle
Jan 16, 2014
Source: Ronald F. Billings, Texas Forest Service, forestryimages.org Damage to a forest from the Southern pine beetle

The cold didn’t snap quite hard enough to kill the hardiest bugs out there, suspect scientists from Rutgers Cooperative Extension Service. The ticks just keep on ticking, and even the freeze-sensitive Southern pine beetle may not have been stopped from doing damage to South Jersey Pinelands trees.

But to be sure about the pine beetle, tree samples will be sent to experts for analysis, said spokesmen from the New Jersey Forestry Service.

The trending beetle blight in the Pinelands south of Mullica River, which has jumped the river north to isolated forest spots including in Stafford Township, made the New York Times in December amid debate that global warming is allowing them to spread northward. Pine trees turn telltale yellow after the larvae devour inner bark and transmit fungi that cuts off water circulation within the tree.

“I don’t think the cold snap was long enough to do any remediation as far as the tick population,” said Linda Schoch, one of two horticulturists with Rutgers Cooperative Extension Service of Ocean County.

Did the subzero temperatures and double-digit wind chills of Jan. 7 and 8 bore into the pine trees where the beetle larvae lurked? That’s what samplings of the tree will seek to find out.

“For 36 hours or 48 hours, I don’t know if it had enough of an effect, but I guess within the next year we’ll know,” said Schoch. “They (researchers) told us we have not had winters cold enough. I think it will depend on how the rest of the winter goes.”

David Finely, regional forester with the New Jersey State Forestry Service, said arrangements are being made for U.S. Forest Service entomologists from Louisiana to either come here to take core samples (known as bolt tests) from trees, or for the samples to be shipped to them for study. Experts from Dartmouth University may also be consulted.

The specialists will inspect whether any larvae present are Southern pine beetle larvae, and if so, what condition they are in, he said.

Infestations have been documented in the Mullica River corridor, most of them south of the river in Atlantic and Cumberland counties. But “it has crept up into Ocean County,” Schoch said.

Finely added that among “very few spots north of the river,” private land in Stafford Township has been documented with the pine beetle.

“There was one spot up in Stafford – I think it died out finally,” he said. “If they run out of food source, they end up dispersing. Or, the beetles may not have all died, but there may not have been enough of them to colonize a tree. It takes hundreds or thousands to kill a tree, and it depends on the condition of the tree.”

The recent frigid but short-lived cold snap “was encouraging, but we won’t really know until we get the bolt test results in,” Finely concluded. The samples probably won’t enter the laboratory before another month, he said.

The scientists will look at the tree bark samples “and seek what has been happening with the beetles in this cold weather. They’ll identify which larvae are Southern pine beetle larvae, and hopefully see what end stage of development they’re in. One stage is a little more cold-hardy than other stages.”

If zero-degree temperatures got inside the bark, “that should knock out some of the population,” Finely said. But questions remain. For one, the exact temperature required to kill the beetles varies in different reports. One study suggests that 8 degrees below zero is required.

“In Millville, we did have minus-5 degrees the one morning, and I think down to around zero, or close to it, the other morning. But this has to be inside the bark where the beetle larvae is,” said Finely.

In New Jersey, the beetle devastation peaked in 2010, killing trees across a 14,000-acre swath on state and private land. Since then, the damage has dwindled to a few thousand acres a year, said published reports. But Dartmouth biologist Matthew P. Ayres was quoted in the New York Times as saying that if climatic warming continues, the pine tree damage could accelerate in the Pinelands and extend to the coasts.

Currently, the management response on state forest land is to cut down the blighted trees.

A final word on ticks in the Pineland locales: don’t latch onto any hopes of their eradication last week. Seasoned woodsmen say the critters are still seen out and about, the week after any deep freeze.

—Maria Scandale


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