Part 4: Good News About the Future form Dr. Richard McDonald
Story by Sam Calhoun
Good news.
In our reports over the past few weeks in this continuing series, news about the widespread infestation of the hemlock wooly adelgid (HWA) has seemed anything but good. But once Dr. Richard McDonald—entomologist, sole proprietor of Symbiont Pest Management and former biocontrol administrator of the North Carolina Department of Agriculture—begins talking about the future of controlling the HWA with three species of beetles, it begins to seem as if the situation’s going to be all right.
He wouldn’t have given the same report last year at this time, but that was before he had reliable data on new natural enemies of the HWA.
McDonald began studying the HWA in 1999, two years after he left the NC Department of Agriculture. Since then, he has been highly involved with research on the HWA at his alma mater, Virginia Tech; he has taken several trips to the Pacific Northwest to study the balance between species of beetles and the HWA; and he has collected perhaps the most data of any individual in our region about the release of predatory beetles.
His goal is simple: “I’m trying to save as many hemlocks as fast as I can by using these bugs.”
Answers from the Pacific Northwest…
According to McDonald, the answers to the High Country’s HWA problem came from the Pacific Northwest. At an HWA conference at Virginia Tech, the discussion centered on how Carolina and Eastern Hemlocks (the trees infested with HWA in the High Country) are living and thriving in the Pacific Northwest, even though they are infested with HWA.
But how? McDonald had to see for himself. He planned a trip to the region with the idea of collecting beetles for testing back east, and what he found amazed him. On a trip to the Seattle Golf Course, he found loads of Eastern Hemlocks—healthy trees that had survived since the 1940s and had resisted heavy infestations of HWA.
The secret was the Laricobius nigrinus predatory beetle; McDonald calls it Lari for conversation’s sake. Because of Lari, 60- to 70-year-old hemlocks, all with HWA, have survived with no pesticides because “they have entered into a balance,” explained McDonald.
In recent articles in this series, the idea of balancing the HWA with natural predators has been at the top of many experts’ to-do-lists, but this achievement has been difficult because predatory beetles are not native to this region and because, as McDonald points out, “the fire department didn’t get called until the house was already half on fire.”
However, McDonald is optimistic about the data he has collected on distributing three kinds of beetles in our region to combat the HWA.
“We’ve lost so much time—we have to work strategically now,” said McDonald.
The Strategy…
“Most trees in our area have gone through the burn down—they’re fried. But they’re not gone. They’re going to go through the burn down, but they’re not dead,” said McDonald. “If we get enough of these bugs out, they will save these trees.
“We’re going to save the hemlock ecosystem—not individual trees. These bugs hold the key,” he added.
McDonald’s strategy involves many factors.
First, McDonald wants everyone in our region to lobby elected officials for a massive pork barrel project that would provide money for raising and collecting these predatory beetles, as well as establishing local insectaries for rearing the bugs.
Second, anyone who has released these beetles or is thinking about releasing beetles should get together so that proper quantities are released in the right areas. McDonald explained that if too many beetles are released in one area, they look at each other and figure out that there’s not enough food and leave. If 300 beetles are released on one tree, he explained, chances are that they’ll leave the area, but if a few beetles are released in an area, they tend to stay.
“As long as they’ve got food, they’ll stay in the area,” he said.
McDonald suggested keeping and sharing records of releases. “We need to keep this as orderly as possible,” he added. “Too many predators is not good.”
Third, there needs to be a massive replanting of hemlocks. This may seem like a death wish for our forests, but McDonald said that once a balance is reached, the hemlock replanting will assist ongoing efforts.
Fourth, McDonald said, people should not go to the Pacific Northwest and collect their own beetles to bring back. Beetle collection should rest in the hands of the National Forest Service so a new strain of HWA is not introduced here.
There are three strains of HWA, he explained. The Japanese strain is in the High Country and it most likely came from the weeping hemlock trade that occurred decades ago between Japan and America. The Japanese HWA traveled with the shipped plants and was introduced to America. There is also an HWA native to the Pacific Northwest and an HWA native to China. According to McDonald, our region would have difficulty combating the Chinese strain, thus the Forest Service should oversee future collections.
The Beetles…
Lari is good, but it can’t do what it does best all year round. It needs some friends.
According to McDonald, additional predators (beetles) that are active at different times of the year are needed to keep pressure on the HWA so no season allows a predator-free population increase.
The control technique involving more than one predator is called bracketing. To bracket is to surround all life stages of the HWA with a predator or another control agent.
Lari only feeds during the winter (mid-October to May), so the spring, summer and fall are a predator-free vacation for the HWA. That’s where Lari’s friends come in.
The Scymnus sinuanodulus beetle and the Sasajiscymnus tsugae beetle take charge where Lari leaves off. Combined, all three beetles bracket the HWA completely.
The Scymnus sinuanodulus beetle is native to China and is significant because it can feed on the HWA for one year, taking in an unlimited amount of food. It is roughly 1.8-inch long.
The Sasajiscymnus tsugae beetle is native to Japan (see a pattern here concerning balance?) and can produce three generations in one year. It is also roughly 1.8-inch long.
“Bracketing with natural enemies causes the populations to crash quickly,” added McDonald.
McDonald has conducted tests with all three of these beetles and feels that the solution has finally been found. Now he hopes that elected officials will get behind the cause and allocate money to raise and release these natural predators.McDonald owes a lot of his research to the Blue Ridge Resource Conservation and Development (BRRCD). The BRRCD was instrumental in establishing the Lees-McRae campus as a test site for Lari. Out of 40 test sites on the East Coast, Lees-McRae is responding the best so far as the site have reared a third generation of the Lari from the initial release.
“If it wasn’t for the BRRCD, this wouldn’t be happening,” McDonald said.
As a side note, the work of the BRRCD, an entity of the United States Department of Agriculture, is being threatened by a lack of funds from the government—another reason why additional money is so important to the health of the region’s hemlocks and another reason to lobby elected officials to sustain this vital service to our area.
Final Thoughts…
McDonald is “very optimistic” about achieving a balance between the HWA, Eastern and Carolina Hemlocks and the three kinds of beetles. He wants people to know that we need to get the bugs out in as many areas of our region as soon as possible—and we need to communicate as a community about it.
“We will stop this cold if we have enough bugs,” he added. “Hemlocks are the greatest air conditioning unit that God ever put up here,” he said, referencing the hemlocks’ canopy that cools rivers, streams, lakes and, by default, ecosystems. “And for me, the solution was as simple as a plane ticket to Seattle, Washington.”
McDonald added, “This [use of bracketing] is all good news. We just need to get people organized and put the pedal to the metal.”
TO PART 5
If you have comments or experiences that you think will help with this community education project, send them via email to sam@highcountrynews.info.
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