News and Events
Since 2002, forests in the southeastern U.S. have struggled against a disease called laurel wilt. In 18 years, laurel wilt has spread to 11 southeastern states and killed hundreds of millions of trees. A review article by USDA Forest Service scientist Rabiu Olatinwo reflects on the origins and spread of laurel wilt throughout the last several years.
The redbay ambrosia beetle (Xyleborus glabratus) and a fungal pathogen (Raffaelea lauricola) were first introduced to the U.S. in the early 2000s. Since then, the deadly duo known as laurel wilt disease has cause widespread mortality among redbay (Persea borbonia), sassafras (Sassafras albidum), and avocado (Persea americana) trees in the southeastern U.S.
Twenty-five years ago, Brian Sullivan saw a fungus growing in bark alongside the small southern pine engraver (Ips avulsus). The beetle is native to the U.S. and commonly kills stressed pine trees.
Twenty-five years ago, Brian Sullivan saw a fungus growing in bark alongside the small southern pine engraver (Ips avulsus). The beetle is native to the U.S. and commonly kills stressed pine trees. Sullivan, a USDA Forest Service research entomologist, examined the fungus. He identified its genus but could not identify the species – the fungus was new to science and had never been described. Sullivan provided mycologist Thomas Harrington and his colleagues at Iowa State University with specimens of the fungus growing within beetle-infested bark.
Chinese privet (Ligustrum sinense) is one of the worst invasive plants in the South. It dominates the shrub layer and often becomes the only shrub underneath trees, especially in streamside areas. But insects and spiders living in fallen leaves and leaf litter were not affected by a privet invasion in Georgia, as a recent study shows.
Callery pear (Pyrus calleryana) can be found across most of the eastern U.S. and in a few western states as well. The nonnative tree was brought to the U.S. in 1917 by a USDA employee searching for a blight-resistant species that could be bred with European pear to increase fruit production. The most common Callery pear cultivar is the Bradford pear. In the last two decades, this near-ubiquitous landscaping tree has been identified as a serious invasive pest. A new publication examines herbicide treatments to control the spread of Callery pear. Lead author J.T. Vogt is a research scientist with the USDA Forest Service.
Eastern hemlock, American chestnut, sassafras, redbay, every member of the ash family, and many others are plagued by non-native invasive species. A new book synthesizes current science on species invading U.S. forests, grasslands, and waterways. The book was published by Springer, and the entire book is available to download. The book covers invasive species of all taxonomic groups from insects and pathogens, to plants, vertebrates, and aquatic organisms.
Forests of the southern U.S. are among the most productive and intensively managed in the world. Disturbances naturally alter forest stands, sometimes creating conditions that benefit plant or animal communities, but can cause major economic losses to landowners. What’s more, the impacts from one disturbance may invite other disturbances – dead and damaged trees can attract bark beetles, wood-boring beetles, or diseases.
Dead wood is a secret harbor of biodiversity. About one-third of all insect species are saproxylic – or dependent upon dead wood – at some stage in their life cycle. USDA Forest Service research entomologist Michael Ulyshen with colleagues Andrea Lucky from the University of Florida and Timothy T. Work from University of Quebec investigated how fire, a common forest management tool in southern pine forests, affected insects that use dead wood.
Seeds that float in the air can hitchhike in unusual places – like the air-intake grille of a refrigerated shipping container. A team of researchers from the USDA Forest Service, Arkansas State University, and other organizations recently conducted a study that involved vacuuming seeds from air-intake grilles over two seasons at the Port of Savannah, Georgia.
An Eastern hemlock can live for 800 years, anchoring ecosystems from its roots to its branches. But a bug that’s a speck by the eye can kill these giants in just a few years. Foresters, entomologists, silviculturists, physiologists, and other experts have been working together to keep hemlock trees alive and reduce the impact of this devastating insect, the hemlock woolly adelgid.
Laricobius nigrinus is a small beetle that eats an even smaller bug – the hemlock woolly adelgid, or HWA. Since 2003, Laricobius has been used to help control HWA. But the beetle, which is native to western North America, is only active during the fall, winter and early spring.
In the past decade, sugarberry trees (Celtis laevigata) have been rapidly declining throughout South Carolina and Georgia. Alongside University of Georgia researcher Emilee Poole, USDA Forest Service scientists Scott Horn, Michael Ulyshen, and others studied the distribution and biology of the wood-boring beetle Agrilus macer to determine its role in recent sugarberry mortality.
Old-growth, or primary forests, are classified as having very little human disturbance — and thus they provide a unique opportunity to study life in relatively unchanged settings. Previous research suggests that these ecosystems may provide critical habitat for sensitive species that are absent or rare in other places. However, past studies comparing bee biodiversity in primary and secondary forests have not consistently found this to be the case.
Shipping containers are stacked like Legos. From all over the world, they have arrived at the Garden City Terminal, at the Port of Savannah in Georgia. About a third of the plant species growing there are also from around the world – they are non-native. Some are new to Georgia and the U.S. altogether. That’s a remarkably high proportion of non-native species, according to a recent study led by USDA Forest Service research ecologist Rima Lucardi.
Andy Whittier has collected hundreds of thousands of seeds during his 17 years with Camcore and the USDA Forest Service. Whittier regularly tests seed germination rates in order to evaluate their quality. That’s how he ended up with 1,200 Eastern hemlocks (Tsuga canadensis) in a greenhouse in Waynesville, North Carolina.
Our newest hemlock experiment is in the ground! We are looking at how various light levels in a forest stand affect hemlock seedlings and the woolly adelgid. In order to investigate these questions we planted hemlocks along a north-south transect in forest gaps and a control group under forest canopy. The gaps were created as part of a previously implemented silviculture experiment that involved group selection harvests in a method termed “femelschlag” that mimics natural forest disturbance patterns.
In recent decades, thousand cankers disease has become a concern for walnut growers and hardwood forest managers in the United States. A variety of measures have been investigated or developed to counter the disease. A study led by USDA Forest Service research entomologist Albert Mayfield and former University of Tennessee graduate student Jackson Audley looked at one measure: quarantine treatments.
Longleaf pine forests are important ecosystems for a broad array of wildlife and understory plant species, such as the red-cockaded woodpecker, the southeastern fox squirrel, and the venus fly trap. Over time, the forests have dwindled due to replacement by other land uses and the suppression of fires with which they evolved. Now, they are a focus of restoration efforts.
“Eastern hemlock is a shade-tolerant species,” says USDA Forest Service research entomologist Bud Mayfield. “But extra sunlight may help it survive HWA infestation.” Extra sunlight equals fewer HWA, at least on potted hemlock seedlings grown under shade cloth.
“About a third of all forest insect species are saproxylic,” says USDA Forest Service research entomologist Michael Ulyshen.
Ulyshen recently edited a definitive new book called Saproxylic Insects: Diversity, Ecology and Conservation and wrote four chapters.
Approximately one third of all forest insect species worldwide depend directly or indirectly on dying or dead wood (i.e., saproxylic) and these organisms are known to be sensitive to forest management decisions. The loss of saproxylic insect diversity in Europe due to reductions in the amount of dead wood and old trees across the landscape serves as a cautionary tale for researchers and land managers working in other parts of the world. This presentation will provide a broad overview of these insects, their conservation and the ecosystem services they provide, with a focus on the southeastern United States.
We are busy this spring releasing our new biological control agent, the silver fly.
Do you remember that hemlock woolly adelgid has 2 generations each year? Our best predators so far all feed on the fall/winter generation. So, unless all the adelgid are eaten or die, come spring time a whole new generation emerges to feed and reproduce. We are hopeful that theses silver flies will put a real hurtin' on that spring generation so we can reduce adelgid levels and relieve the pest pressure on our hemlock trees year round.
This is the time of year when the progrediens generation of hemlock woolly adelgid (HWA) is out in full force crawling out of their white, woolly ovisacs and looking for a place to settle at the base of a nice green hemlock needle.
A handful of the world’s 3,100 known termite species damage homes. In forests, however, termites are valuable.
“Termites recycle dead wood,” says U.S. Forest Service research entomologist Michael Ulyshen. Termites consume as much as 20 percent of the dead wood in forests, as Ulyshen showed in 2014.
In the Northern Hemisphere, winter officially starts at the same time every year. In 2017 it was on a Thursday, December 21st, the shortest day of the year. The Winter Solstice. And winter has swept into the Southeastern U.S. with some teeth this year.
On September 17, more than 35,000 insect enthusiasts gathered at the North Carolina Museum of Natural Sciences in Raleigh, NC.
U.S. Forest Service employees were among them. As in years past, the Southern Research Station had a table at BugFest. Hundreds of children and adults stopped by to learn about SRS research and to see insects up close.
We are at it again, setting up wood wasp traps as part of a localized survey to detect native siricids and parasitoids. A wood wasp native to Europe, Sirex noctilio, has been introduced to parts of the U.S. For now, the non-native species has only been detected in portions of NY, PA, MI, and VT. Our southern pine species would be prime habitat for these critters though, so we are making attempts to detect the insect.
In a controlled experiment, as many variables as possible are accounted for, a hypothesis is conceived. The experiment is carefully planned, laid out, and implemented.
Take all of that planning and equipment to the field however...
We have been at it again this spring with a new predator of hemlock woolly adelgid (HWA). This is our third consecutive year releasing silver flies on HWA infested hemlocks.
Yep, the "daylighting" of hemlocks has finally begun!
Based on what we know from anectodal evidence in the field and research done in a nursery setting we can say that hemlocks in full sun tend to be healthier and have lower levels of adelgid infestation. So, we are bringing that hypothesis to the big woods and trying out a new experiment. This study has been on paper for quite a while and we have been scouting sites for the better part of a year.
Up to 30 percent of all forest insect species depend on wood that is dead or dying. “Such species are among the most threatened insects in Europe,” says U.S. Forest Service scientist Michael Ulyshen. “However, very little is known about their diversity or conservation status in North America.”
SRS research entomologist Bud Mayfield was relieved to find that defoliation on an American chestnut planting site was not as severe as expected. Mayfield and SRS research forester Stacy Clark are coauthors on a paper in the Journal of Insect Science that describes a study they conducted with Ashley Case, an adjunct lecturer at the University of North Carolina at Asheville.
Scientists have identified a potential new strategy for protecting hemlocks from the miniscule insect that plagues them. “High levels of sunlight help reduce hemlock woolly adelgid abundance on young seedlings,” says U.S. Forest Service project leader Bud Mayfield. “Follow-up experiments in the field are still needed, but the results suggest thinning or strategically creating gaps in the forest could help conserve hemlocks.”
Bees are a critical part of many flowering plants’ reproductive cycles. “By some estimates, nearly 90 percent of the world’s flowering plants are pollinated by bees, butterflies, beetles, or other pollinators,” says U.S. Forest Service research entomologist Michael Ulyshen. “There is also growing evidence that many pollinators are declining.”
Kudzu, the nightmare weed that gobbled the South, is disappearing.
Slowly, inexorably, the scientists, foresters, farmers and goats — yes, goats — are gaining the upper hand on the slinky, creepy green vine that makes abandoned homes and utility poles disappear seemingly overnight.
Over the past decade, U.S. Forest Service researchers have been working with university cooperators to find some way to slow down or stop the relentless spread of cogongrass. In late 2014, Auburn University researchers reported results that demonstrated, for the first time, that patches of cogongrass can be eliminated completely within three years — showing that eradication of the invasive plant is actually possible for many land managers.
It grows on every continent except Antarctica and has earned a reputation as one of the worst weeds on earth — and according to U.S. Forest Service emeritus scientist Jim Miller, cogongrass (Imperata cylindrica) is without doubt one of the most threatening invasive species in the South.
Forests in North America have changed rapidly over the past century. Before European settlement, forests were a mosaic of open pine and hardwood forests, prairies, and woodland savannas. Recent studies have found that forests with sun-filled openings and those with open canopies — where the branches from adjacent trees don’t touch or overlap — favor pollinators like bees and butterflies.
Forests infested with privet invoke a kind of despair in people attuned to the problem of invasive plants. Privet invades a forest quickly, sprawling across the understory and growing into thickets that crowd out native plants and change the very ecology of an area. Even if the woody shrub can be removed effectively, can a forest return to any semblance of its previous condition?
Guidelines for Regenerating Southern Pine Beetle Spots, a general technical report (GTR) by the U.S. Forest Service Southern Research Station (SRS), provides detailed guidance for regenerating pines in areas within forest stands where trees have been killed by the southern pine beetle.
Originally from Asia, the redbay ambrosia beetle and the fungus it carries in its jaws have found a new home in the southern United States. Eradication is impossible at this point, and the fungus causes laurel wilt, a highly destructive disease that affects redbay, swamp bay, sassafras, avocado, and pondberry – as well as every other member of the laurel family.
The redbay laurels that once graced the coastal forests and residential landscapes of the Southeast have all but disappeared, taken down by laurel wilt, a deadly disease caused by a fungus (Raffaelea lauricola) carried in the jaws of the nonnative redbay ambrosia beetle (Xyleborus glabratus).
On Friday last week, U.S. Forest Service scientists with the Southern Research Station and Forest Health Protection released just over 1200 Laricobius osakensis beetles on eastern hemlock trees in North and South Carolina. Reared at University of Tennessee Knoxville’s Lindsay Young Beneficial Insects Lab, the predator beetles are natural enemies of the hemlock woolly adelgid, an invasive insect that kills hemlock trees in eastern North America.