Walnut twig beetle, native and invasive in the U. S.

Walnut twig beetle (Pityophthorus juglandis) is believed to be native to the southwest but has spread to the eastern U. S., bringing thousand canker disease (fungus: Geosimithia morbia) with it.  Genetic testing reveals that there are two different geographic lineages but areas where the beetle is invasive, they have hybridized.  The two lineages may be considered as two separate species.

Walnut twig beetle (Pityophthorus juglandis) by Steven Valley, Oregon Department of Agriculture, Bugwood.org

Thousand canker disease occurs where the beetle has infested walnut trees.  The fungus grows under the bark of the tree wherever the beetles enter, forming many small cankers which cut off the flow of nutrients throughout the tree.  Diseased tree may die in as little as three years.  The beetles and disease were first found in the eastern U. S. in 2010 and have attacked many walnut trees, causing damage to crops and urban forests.

Thousand canker disease (Geosimithia morbia) by Ned Tisserat, Colorado State University, Bugwood.org

Source article: Walnut twig beetle's origin, spread revealed in genetic studies
Walnut twig beetle images: Pityophthorus juglandis
Thousand canker disease images: Geosmithia morbida
Walnut twig beetle BugwoodWiki article: Pityophthorus juglandis

New pine beetle discovered in Central America: Mesoamerican pine beetle

Called the Mesoamerican pine beetle (Dendroctonus mesoamericanus), it is in the same genus as southern pine beetle, a destructive bark beetle that attacks several species of pine.  After suspecting the existence of a new species of bark beetle in 2002, subsequent pheromone and body wax chemistry definitively proved the new species.  In fact, the Mesoamerican pine beetle don't response to pheromone traps baited for southern pine beetle.

southern pine beetle (Dendroctonus frontalis) by Erich G. Vallery, USDA Forest Service - SRS-4552, Bugwood.org

The Mesoamerican pine beetle looks very similar to the southern pine beetle, but, in addition to the chemical differences, the Mesoamerican pine beetle tends to be larger and has other subtle morphological differences, the resinous pitch tubes on infested trees are also larger, they tend to infest the trees after they have already been colonized by southern pine beetles, and they are found in the lower trunk and branches.  They have been found on eight species of pines in Central America and are believed to work in concert with southern pine beetles.  The combination of beetles on infested trees tends to be more destructive than those infested by southern pine beetle alone.

southern pine beetle pitch tubes by Erich G. Vallery, USDA Forest Service - SRS-4552, Bugwood.org

For more on the discovery: New Mesoamerican pine beetle described by scientists
To access the original publication: A New Species of Bark Beetle, Dendroctonus mesoamericanus
sp. nov. (Curculionidae: Scolytinae), in Southern Mexico and Central America

Massive die-off of Sierra Nevada trees; With drought comes beetles

Thousands of acres on public and private lands are home to dead and dying trees, and this makes forestry and fire officials concerned.  Western pine beetles thrive in drought, when the Ponderosa pines natural sap defenses are weakened, and only wet years will reduce populations.  All types of conifer trees are being affected by the drought, with some succumbing to drought and some from the bark beetles that are moving in.  Either way, large numbers of dead trees are a fire hazard and are being removed on public lands and private at a cost of upwards of hundreds of dollars per tree.  Those in the logging industry blame the Forest Service for not allowing thinning on public lands, but natural resources economist John T. Austin likens the current tree mortality to a hot patchy fire.  While the trees aren't being selectively thinned by the drought and the bark beetles, but it will leave behind the healthier trees and a greater diversity.

mountain pine beetle (Dendroctonus ponderosae) on ponderosa pine near Antero Jct, South Park,CO by William M. Ciesla, Forest Health Management International, Bugwood.org

*Note: image is not from current drought

To view the article: Sierra Nevada pine tree die-off worsens as beetles thrive in drought
To view a map of the drought: U.S. Drought Monitor

The green menace strikes again! Human health effects of Emerald Ash Borer

Steven Valley, Oregon Department of Agriculture, Bugwood.org

PBS NewsHour just published a piece on How Removing Trees Can Kill You as related to the loss of ash in Detroit, Michigan as a result of Emerald Ash Borer. 

Geoffrey Donovan noted "Increased rates of death from cardiovascular and lower respiratory mortality in the counties with emerald ash borer. And interestingly, what we found was the effect got bigger the longer you had an infestation, which makes sense because it takes two to five years for a tree to die typically."

I've always touted the fact that trees in urban environments make it a better place to live. It takes something like this to make you appreciate just how important they can be!

Emerald Ash Borer continues its march into Pennsylvania

Emerald Ash Borer has continued its spread into Pennsylvania and has now been detected in Bedford County.  This pest has been devastating the native ash trees as it has spread from the orignial introduction in Michigan.  The Pennsylvania Department of Agriculture is again urging campers not to move firewood since it is the primary way that this pest is spread.  See the PA Department of Agriculture website for the full news release.

Bark Beetles of the Southeastern United States

CPHST is pleased to announce the release of a new identification tool, An Identification Tool for Bark Beetles of the Southeastern United States. Bark Beetles of the Southeastern United States was created through collaboration among USDA/APHIS/PPQ Center for Plant Health Science and Technology (CPHST), North Carolina State University (NCSU), Cooperative State Research, Education, and Extension Service (CSREES), Southern Plant Diagnostic Network (SPDN), Oregon Department of Agriculture, and Museum Victoria, Australia (PaDIL image library). The internet-based tool separates southeastern United States genera contained within the Curculionidae subfamily Scolytinae, focusing specifically on members of the tribes Hylesinini and Scolytini.

Bark Beetles of the Southeastern United States, developed and released in Lucid version 3.4, was uploaded to the Internet in January 2010 to support easy access by PPQ and our cooperators. Bark Beetles of the Southeastern United States can be accessed at: http://keys.lucidcentral.org/keys/bark_beetles.htm

Some of the images from this project are available through the Bugwood Image Database.  Below are the links to some of the image galleries:

•   J.R. Baker & S.B. Bambara 
•  Pest and Diseases Image Library (PaDIL)