Examples of Ohio's invasive species include tree pests such as emerald ash borer and Asian longhorned beetle; aggressive plants such as kudzu, garlic-mustard, callery pear, bush honeysuckles and hydrilla, an aquatic weed; West Nile virus; zebra mussel; and round goby, a fish.
Other Ohio invaders include plants such as common reed, tree-of-heaven and Canada thistle; tree pests and diseases such as gypsy moth, chestnut blight and Dutch elm disease; European corn borer, a major corn crop pest; aquatic species including the common carp and sea lamprey, the latter being a primitive fish that parasitizes game fish; and birds such as the house sparrow and European starling, both of which muscle out bluebirds and other native species for nest sites.
More recent arrivals include feral pigs, white-nose syndrome in bats, the hemlock tree killer called hemlock woolly adelgid, the aggressive ground-covering plant called lesser celandine, and the walnut twig beetle, which can spread deadly thousand cankers disease in walnut trees.
Among invasive species' harmful impacts in Ohio:
*The zebra mussel and its cousin, the quagga mussel, cost U.S. and Canadian water users in the Great Lakes region an estimated $5 billion from 2000 to 2010, according to the U.S. Fish and Wildlife Service. How: By clogging municipal water-intake pipes and requiring costly cleanup and prevention.
*Bush honeysuckle plants are causing Ohio's state bird, the cardinal, to be less genetically fit, an Ohio State study reported. The non-native shrubs produce less-nutritious berries than those of displaced native dogwoods and highbush cranberries. Male cardinals that eat the inferior berries end up less healthy but still keep their trademark bright red color, which normally tells a female that they'll make a quality mate. But in this case, due to their diet, they won't. When females choose these vivid but secretly weaker males, the "survival of the fittest" reproductive strategy gets disrupted.
Cardinals nesting in bush honeysuckles also fledged 20 percent fewer young, another Ohio State study found, leading the study's authors to call the plants "ecological traps."
*At risk from the potential arrival of Asian carps -- not just the silver but the grass, black and bighead, too -- is a Great Lakes commercial fishery worth $7 billion, according to the Congressional Research Service. Lake Erie produces more of that harvest than the other Great Lakes combined, says a study by Michigan Sea Grant Extension.
*Japanese barberry creates a denser, more humid environment in forests. The change leads to big increases in the number of ticks and the mice that spread them, a Connecticut study found. Smith said bush honeysuckles may do the same thing.
*In places, white-nose syndrome has killed 90 to 100% of the bats hibernating in caves in winter. Bats provide an average of $740 million a year worth of pest-eating services to Ohio farmers, according to a study in the journal Science.
*Thousand cankers disease, if it comes to Ohio, threatens all of the state's walnut trees, which produce lumber worth $1.2 billion and tons of edible nuts. The disease is spread by the walnut twig beetle, which was found in Ohio for the first time in late 2012, but the disease itself hasn't appeared.