Photo: Michael Bohne, Bugwood.org, University of Georgia; Male Asian longhorned beetle
For clarification, invasive species are non-native (non-indigenous to North America) organisms that become established and cause harm to the native environment. In this case, the "environment" is the production and maintenance of ornamental plants.
How do they get here and why do they do so well?
There are three primary routes of entry. Some invasive species, particularly plants, were intentionally brought to the US for a specific purpose, but escaped into the wild, or acted in an unexpected manner after their release. Other pests have entered the country in or on host plants, or they arrived on shipping and packing material. These introduced species perform so well because there are no naturally occurring pathogens, predators or parasites that can keep the population in check. Also, this new environment may prove to be more conducive to the growth and reproduction of the non-native species compared to the native inhabitants.
Some examples of invasive species that have impacted ornamental plants include: black vine weevil (Otiorhyncus sulcatus, origin: Europe); emerald ash borer (Agrilus planipennis, origin: eastern Russia, northern China, Japan, Korea); gypsy moth (Lymantria dispar, origin: Europe); hemlock woolly adelgid (Adelges tsugae, origin: Japan); Japanese beetle (Popillia japonica, origin: Japan); Asian longhorned beetle (Anoplophora glabripennis, origin: China); smaller Japanese cedar longhorn beetle (Callidiellum rufipene, origin: Japan, Korea & Taiwan); chestnut blight (Cryphonectria parasitica, origin: China & Japan); and Dutch elm disease (Ceratocystis ulmi, origin: Europe).
What can be done?
Once a new species is detected, there are other factors besides its biological capabilities that can complicate its containment and eradication. The cost may prove to be excessive, and the emergence of pest populations in several areas may also slow down the management process. Thus, the most important step in management of invasive species is prevention. At the federal level, this responsibility falls primarily on USDA APHIS. Under the new Plant Protection Act, which consolidated the Plant Quarantine Act, Federal Plant Pest Act and Federal Noxious Weed Act, APHIS is authorized to prohibit or restrict the importation or interstate movement of any plant, plant product, biological control organism or plant pest. A plant pest includes almost any living organism (other than human) that damages or causes disease.
However, APHIS is not the only federal agency involved with the exclusion or eradication of invasive species. The Fish & Wildlife Service (FWS), within the Department of Interior, regulates animals (mammals, birds, fish, amphibians, reptiles, mollusks and crustaceans) under the Lacey Act. The Nonindigenous Aquatic Nuisance Prevention & Control Act was implemented to prevent and control aquatic nuisance species. There are a multitude of agencies that enforce this one: FWS; National Oceanic and Atmospheric Administration (NOAA); US Coast Guard; Army Corps of Engineers; APHIS; Environmental Protection Agency (EPA); and the Department of State.
The Department of Defense (DOD) is also involved with invasive species management when it assists APHIS with inspection of military shipments into and out of the US. The DOD monitors for invasives on all military bases. Finally, the US Customs Service detains products that are awaiting APHIS or FWS inspection.
More information on the federal role in the control of invasive species.
In Pennsylvania, the Pennsylvania Department of Agriculture (PDA) has the responsibilities of protecting nursery and landscape plants from non-native pests, and working with federal agencies to prevent pest infestations. PDA ensures the protection of PA's ornamental plants through three procedures. First, PDA has the power to establish quarantines and can develop regulations for the seizure, inspection, disinfection and destruction of infested plants. Second, to minimize the risk of pest infiltration, PDA requires certification that all incoming plants have been inspected and declared pest free. Third, PDA conducts annual inspections of all registered nurseries to ensure that Pennsylvania grown plants are free of insect and disease pests.
Federal and state agencies provide a high level of protection, but what can you do? Regular monitoring/scouting of plant material is the key to a successful integrated pest management (IPM) program. Thus, monitoring is essential for the detection of new pests, native or foreign, in the nursery or landscape. For the nursery, knowledgeable personnel should inspect new plant shipments that arrive from other states or countries as soon as possible. A detailed visual inspection of all plant parts (leaves, woody material and roots) on at least 15% of the plants, along with a general observation of the remaining plants, should be conducted.
The inspection can follow an "X-pattern" or serpentine pattern through the entire block with random stops to sample the 15%. If the plants are not checked upon arrival, a "quarantine area" can be designed for placement of new arrivals. This area can be a greenhouse(s) or hoop house(s) near the loading/unloading site. This area would contain any potential pests at one location before the plants are moved to other nursery locations. At any time during plant inspections, if an unknown organism is discovered, you can contact Penn State Extension or transport a sample directly to an Extension office for assistance with proper identification. A quick response time limits the spread and potential damage from any pest.
Prevention is the easiest and most cost-effective step. If the non-native species has already escaped, the control and management steps become more costly and are usually less effective. Eradication of an invasive species is extremely difficult if not impossible. The management focus then shifts from eradication to population suppression, limiting the spread and reducing the effects. The overall goal is to restore the environment to its natural state. All of the agencies mentioned previously, that are involved with prevention (i.e. interception) of invasive species, also have research programs that focus on new prevention strategies, species biology or control options.
With the increased volume and speed of national and international trade, the risk of invasive species increases. Education of green industry professionals, and the general public, is crucial to reduce the risk of invasive species to the financial and ecological well being of the United States. Do your part to prevent the movement of invasive species. Follow all state and federal regulations, and take the time to check incoming plants to ensure that no new pests become established.