According to a study conducted by researchers at UC Santa Barbara's National Center for Ecological Analysis and Synthesis, however, what has proved to be a boon for the economy has also been shown to have devastating effects on the environment.
High densities of the hemlock woolly adelgid, an insect native to East Asia that feeds by sucking sap from hemlock trees. In North America, it poses a major threat to eastern and Carolina hemlocks.
Balsam woolly adelgids, small wingless insects that infest and kill firs, especially Balsam Fir and Fraser Fir, were introduced from Europe around 1900. They have destroyed roughly 95 percent of the Fraser firs in the Great Smoky Mountains National Park, and have had a significant impact on forests in the Pacific Northwest.
The multidisciplinary working group found that almost 70 percent of the most damaging non-native forest insects and diseases currently afflicting U.S. forests arrived via imported live plants. The group's findings appear in the current issue of the journal Frontiers in Ecology and the Environment.
The study, led by Andrew Liebhold, a Forest Service researcher with the U.S. Department of Agriculture, shows that in the last 43 years, the quantity of plant imports to the U.S. has risen by more than 500 percent, peaking at 3.15 billion plants in 2007. Nearly half of the imported live plants entering the U.S. are destined for either California or Florida.
Once introduced, some of these imported insects and disease organisms become established, and a fraction of those become major economic pests. For example, Sudden Oak Death, which is caused by the plant pathogen Phytophthora ramorum, was introduced into the Bay Area and Big Sur regions of California via nursery plants. The disease has now spread through 14 counties in California, as well as southern Oregon, where it has caused large-scale die-off of tanoaks, live oaks, and black oaks.
The authors studied 82 high-impact invasive insects and diseases in detail. Of these, 95 percent of sap-feeding insects and 89 percent of foliage-feeding insects probably arrived on live plants. In contrast, roughly 85 percent of wood- and phloem-boring insects likely entered the country on wood packaging materials, logs, lumber, or other wood sources.
"The demand for live plants from outside the United States is not likely to diminish," said Liebhold. "As global trade expands, our knowledge of pest pathways must be improved to ensure trade is accomplished with minimal environmental degradation."
According to Liebhold, the working group's current research provides specific information that is critical to the development of policies to reduce the risk of pest species associated with the trade in live plants. Current policies are based on outdated assumptions about the size and number of shipments, and do not address the very large number of plants now grown abroad for direct resale in the U.S., he said.
The authors describe several possible means to increase bio-security, including intensified efforts at plant inspection stations; precautionary measures that restrict plants from entering the U.S. until they have been assessed as posing very little risk; expanding the post-entry quarantine currently applied mainly to some crop plants to include ornamental plants; developing better advance knowledge about pest insects and pathogens; and developing integrated systems approaches that depend on expanded partnerships between researchers and industry.
Andrea Estrada | EurekAlert!
Conservationists are sounding the alarm: parrots much more threatened than assumed
15.09.2017 | Justus-Liebig-Universität Gießen
A new indicator for marine ecosystem changes: the diatom/dinoflagellate index
21.08.2017 | Leibniz-Institut für Ostseeforschung Warnemünde
Plants and algae use the enzyme Rubisco to fix carbon dioxide, removing it from the atmosphere and converting it into biomass. Algae have figured out a way to increase the efficiency of carbon fixation. They gather most of their Rubisco into a ball-shaped microcompartment called the pyrenoid, which they flood with a high local concentration of carbon dioxide. A team of scientists at Princeton University, the Carnegie Institution for Science, Stanford University and the Max Plank Institute of Biochemistry have unravelled the mysteries of how the pyrenoid is assembled. These insights can help to engineer crops that remove more carbon dioxide from the atmosphere while producing more food.
A warming planet
Our brains house extremely complex neuronal circuits, whose detailed structures are still largely unknown. This is especially true for the so-called cerebral cortex of mammals, where among other things vision, thoughts or spatial orientation are being computed. Here the rules by which nerve cells are connected to each other are only partly understood. A team of scientists around Moritz Helmstaedter at the Frankfiurt Max Planck Institute for Brain Research and Helene Schmidt (Humboldt University in Berlin) have now discovered a surprisingly precise nerve cell connectivity pattern in the part of the cerebral cortex that is responsible for orienting the individual animal or human in space.
The researchers report online in Nature (Schmidt et al., 2017. Axonal synapse sorting in medial entorhinal cortex, DOI: 10.1038/nature24005) that synapses in...
Whispering gallery mode (WGM) resonators are used to make tiny micro-lasers, sensors, switches, routers and other devices. These tiny structures rely on a...
Using ultrafast flashes of laser and x-ray radiation, scientists at the Max Planck Institute of Quantum Optics (Garching, Germany) took snapshots of the briefest electron motion inside a solid material to date. The electron motion lasted only 750 billionths of the billionth of a second before it fainted, setting a new record of human capability to capture ultrafast processes inside solids!
When x-rays shine onto solid materials or large molecules, an electron is pushed away from its original place near the nucleus of the atom, leaving a hole...
For the first time, physicists have successfully imaged spiral magnetic ordering in a multiferroic material. These materials are considered highly promising candidates for future data storage media. The researchers were able to prove their findings using unique quantum sensors that were developed at Basel University and that can analyze electromagnetic fields on the nanometer scale. The results – obtained by scientists from the University of Basel’s Department of Physics, the Swiss Nanoscience Institute, the University of Montpellier and several laboratories from University Paris-Saclay – were recently published in the journal Nature.
Multiferroics are materials that simultaneously react to electric and magnetic fields. These two properties are rarely found together, and their combined...
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