Forest Pests
Entire Forests are Dying
Warming temperatures and droughts are fueling the expansion of pine, mountain and spruce beetle outbreaks across North America, Europe, and Siberia, ravaging tens of thousands of square miles of woodlands. Scientists warn that some forest ecosystems may never recover.
What is the problem? A number of different pests are currently wreaking havoc on our forests. They can be both invasive (e.g. emerald ash borer) and native pests (e.g. bark beetles). Emerald Ash Borer, Hemlock Wooly Adelgid, Gold Spotted Borer, Bark Beetles and others are all causing damage.
Current Status of a Solution
We have identified two candidate microbes to develop those microbes as a solution for a broad range of forest pests. Efficacy testing against beetles, borers, spotted lanternfly and wooly adelgids and other pests are underway.
Once efficacy has been shown we will simultaneously work on manufacturing and application methodology.
Overview
Bark Beetles are tiny insects with hard, cylindrical bodies that feed and breed in the inner bark (phloem) layer of trees. There are 600 different species of bark beetles in the United States. Several species, such as the mountain pine beetle are aggressive and can develop large populations that attack and kill healthy trees causing significant adverse economic and social impacts on the lumber industry, fish and wildlife, water quality, and property values.
Bark beetles enter trees by boring holes in the bark of the tree. As the larvae consume the inner tissues of the tree, they often consume enough of the phloem to girdle the tree, cutting off the spread of water and nutrients. Healthier trees may produce sap, resin or latex, which often contains a number of insecticidal and fungicidal compounds that can kill, injure, or immobilize attacking insects. Released sap or resins can plug bored holes of bark beetles and seal wounds. Some tree species release chemical compounds which bind with amino acids in the gut of bark beetles, reducing their ability to process woody mater. However, climate change, with its warmer temperatures and periodic droughts are overcoming the trees’ natural defenses causing large die off of forests, fires and changing forest ecosystems.
Emerald Ash Borer (Agrilus planipennis), is a green jewel beetle native to north-eastern Asia. Females lay eggs in bark crevices, after hatching, larvae chew through the bark to the inner phloem where they feed and develop to emerge as adults in one to two years. The serpentine feeding galleries of the larvae disrupt the flow of nutrients and water, effectively girdling and thus killing the tree, as it is no longer able to transport sufficient water and nutrients to the leaves to survive. Adults begin to emerge from trees in late spring, after emergence, adults feed for one week on ash leaves in the canopy before mating. Females typical live six weeks and lay approximately 40–70 eggs. Emerald ash borer populations primarily spread through flight or by transportation of ash bark in such products as firewood or nursery stock. Such transport, allows the beetle to reach new areas and create satellite populations outside of the main infestation.
In its native habitat, it is typically found at low densities and does not cause significant damage to trees native to the area. Outside its native range, it is an invasive species and is highly destructive to ash trees native to Europe and North America. The insect was first identified in Michigan in 2002, but it may have been in the U.S. since the late 1980s. It is suspected that it was introduced from overseas in shipping materials such as packing crates. In eastern Europe, a population was found in Moscow, and has spread to far eastern Ukraine. From 2003 to 2016, this population has spread west towards the European Union at up to 40 km (25 mi) per year and is expected to reach central Europe between 2031 and 2036. Every North American ash species has susceptibility to emerald ash borer, after initial infestation, all ash trees are expected to die in an area within 10 years. The emerald ash borer threatens the entire North American genus Fraxinus with extinction. Emerald ash borer kills young ash trees several years before reaching their seeding age of 10 years. In both North America and Europe, the loss of ash from an ecosystem could result in increased numbers of invasive plants, changes in soil nutrients, and effects on species that feed on ash.
Extent and Impact of Infestation
Bark Beetles are most commonly recognized by their impact on the lumber industry. Over the last 20 years, massive infestations of mountain pine bark beetles in western North America have killed millions of acres of forest from New Mexico to British Columbia. The mountain pine beetle, southern pine beetle, and their near relatives are major pests of conifer forests in North America. A similarly aggressive invasive species in Europe is the spruce ips. And coffee plantations around the world are plagued by another major pest, the tiny coffee berry borer.
“The amount of conifer mortality that we’re seeing both here and in Europe is unprecedented historically,” says Jesse Morris, a geographer with the University of Utah in Salt Lake City. Morris and other scientists are trying to determine the potential impacts, such as more intense wildfires, disrupted watersheds, destroyed habitats, and reduced carbon storage, as climate change spurs increasingly widespread and severe beetle outbreaks. Bark beetles are a natural part of the conifer forest life cycle, regularly flaring and fading like fireworks. But the scope and intensity in the past two decades is anything but normal, scientists say, in large part because rising temperatures are preventing the widespread winter die-off of beetle larvae, while also enhancing the beetles’ killing power. Not only are the insects expanding into new territory, they are also hatching earlier and reproducing more frequently. New infestations become full-blown with astonishing speed, and the sheer numbers of beetles exceeds anything forest experts have seen before. Morris says he’s seen spruce beetle epidemics in Utah so intense that when the insects had killed all the trees, they then began attacking telephone poles.
Emerald Ash Borer (EAB) – Ash trees are among the most valuable and abundant North American woodland trees with estimates of ash trees in the United States of between seven and nine billion with an estimated value of more than $280 billion. The emerald ash borer has destroyed 40 million ash trees in Michigan alone and hundreds of millions throughout other states and Canada. As of October 2018, the EAB was found in 35 states, and the Canadian provinces of Ontario, Quebec, New Brunswick, Nova Scotia and Manitoba.
Ash trees are especially abundant in eastern forests, but the mother lode of diversity is actually in the southwestern U.S., where at least eight of 16 native ash species occur. Cultivars of green ash, white ash and velvet ash have also been planted in landscapes and along roadways across the U.S. for decades. Because ash was so commonly propagated, nurseries sustained millions of dollars in losses when the EAB quarantines were imposed. Hundreds of millions of mature urban ash trees are growing on municipal and private land in the U.S. A 2010 analysis in Ecological Economics examined the potential costs of either treating or removing 50 percent of landscape ash trees in urban areas affected by EAB. Projected costs would exceed $10.5 billion by 2019. If suburban ash trees are included, costs nearly double.
Estimating costs of treatment or removal, however, does not do justice to the full economic impacts of losing ash trees, especially large trees, in residential and developed areas. Ash trees comprise up to 50 percent of the municipal trees growing along boulevards and in parks in some cities. Losing a substantial portion of mature trees dramatically alters the appearance of neighborhoods and diminishes property values. Stormwater run-off increases. Shade decreases, and air conditioners run longer. In southeast Michigan municipalities, water use soared as a result of widespread ash mortality, resulting in surcharges levied by the regional water authority. Green ash, the most widely distributed ash in the U.S., grows in many types of soils and is often abundant along rivers, streams and other waterways, as well as in forests. White ash is also widely distributed, frequently growing in mixed stands with oaks, maples and other hardwoods. Black ash occurs most commonly in swamps and bogs in the northern U.S. and parts of Canada, often in sites where it is the only tree present. Unfortunately, black ash is also a highly preferred host for EAB and very vulnerable — it generally takes fewer EAB larvae to kill black ash trees than similarly sized trees of other ash species. The long-term ramifications of ash mortality in forests and riparian settings are not yet known, but can be expected to cascade through ecosystems. Nutrient cycling, hydrology, composition of herbaceous plants and the habitat available for birds, mammals, insects and other animals are all likely to be affected.
Along with its ecological value, black ash has cultural and spiritual significance for many American Indian tribes from Minnesota to Maine, as well as First Nation tribes in Canada. Some tribes even trace their origin to a black ash tree that split — one fork became man and the other became woman. The art of black ash basketry has been handed down from generation to generation in many tribes. Cooperative efforts to collect and preserve ash seeds, including seeds from black ash trees, have been undertaken by a number of tribes, along with scientists from federal agencies and universities.
Current Management
Infested trees are either removed or treated with insecticides Research suggests that insecticide treatments are significantly more effective on EAB-infested ash trees with less than 50% canopy thinning. Insecticide treatments are not recommended for trees with greater than 50% canopy thinning; these trees should be removed. There are four active ingredients used to control emerald ash borer: imidacloprid, dinotefuran, emamectin benzoate, and azadirachtin. Imidacloprid. Imidacloprid is the most easily applied and usually least expensive of the insecticides used to control emerald ash borer.
Biological Control – Three species of small, stingless wasps are being used to control EAB throughout Indiana and the US. These wasps kill large percentages of EAB in their native range in Asia. All wasps have been thoroughly tested to ensure that they will not attack native insects. It is unlikely that these wasps alone will eradicate EAB, but they help protect ash trees growing from seedlings in the forest. Although more wasps are reared every year, they are only given to professionals for release to ensure that they have the best chance for success.