Redistributed as a Service of the National Library for the Environment*
Harmful Non-Native Species: Issues for CongressVI
April 8, 1999
There is no single law that provides coordination among federal agencies in the treatment of non-native species. In 1993, the Office of Technology Assessment found:
Any change in federal policy since 1993 appears incremental at most. To date, legislative effort has involved an ad hoc focus on single species, or on a handful of specific pathways of introduction, or on damages or risks to agriculture.
In one step toward a more comprehensive approach, Representative Charles Canady introduced the Plant Protection Act of 1998 (H.R. 3766) in the 105th Congress to consolidate and modernize all the major statutes pertaining to plant protection and quarantine, including the Federal Noxious Weed Act. (According to APHIS officials, Mr. Canady is expected to reintroduce the bill in the 106th Congress.) Two bills (S. 321 and S. 83) similar to H.R. 3766 were introduced in the Senate in January 1999. Among other things, such proposals would: (1) eliminate the phrase "new or not widely prevalent" from the definition of noxious weeds, which would permit the agency to address all types of weed issues, not just new or recent introductions; (2) facilitate the listing of any weed that is of regulatory concern regardless of origin; (3) increase the maximum civil penalty to $50,000 per violation for individuals and to $250,000 for businesses; and (4) authorize APHIS to take both emergency and extraordinary emergency actions to address incursions of noxious weeds. The proposals do not contain language that would put greater emphasis on the agency's responsibilities regarding weeds harmful to fish and wildlife resources, nor do they directly address issues concerning the entry of non-native animal species, except insofar as these species are plant pests.
President Clinton's Executive Order 13112 (on Invasive Species) now requires federal agencies in general to prevent the introduction of these species as well as to provide for their control and to minimize their impacts through better coordination of federal agency efforts. This effort is to be guided by a National Invasive Species Management Plan to be developed by an interagency Invasive Species Council. Ultimately, the Order could lead not only to greater agency attention to non-native species (its stated purpose) but also to greater coordination among agencies. 39
However, the Order does not provide explicit direction on that critical period between the introduction (or intentional release) of non-native species and the time when the species becomes established and focus must shift from prevention to control. 40 Like the "Golden Hour" after a severe accident, when medical personnel know that the chance of saving a human life is greatest, this "Golden Period" shortly after the chance (or deliberate but ill-conceived) introduction and after prevention has failed, may offer one last chance to prevent the establishment of a new harmful non-native. Moreover, there may be economic and ecological savings from early intervention. For example, the effort to capture a single snake that might be a brown tree snake newly arrived at an airport in Honolulu, even if it were to cost tens of thousands of dollars, would be a bargain if it prevented the millions of dollars that would be spent annually to control the snake if it were to become established on Oahu, and the millions more to compensate for the losses due to the snake.
Exclusion lists currently focus on species that have already been shown to be harmful. An alternative approach would use known characteristics of a species, such as how it reproduces, to predict the risk that it would prove harmful if introduced. New Zealand already uses such a method, and U.S. scientists have been performing research to determine if a similar approach could be developed for this country.
There are substantial gaps in federal laws and programs to prevent the introduction of non-native species, and it is clear that significant risks remain unaddressed. Species are selected for control primarily based on the record of damage they have already inflicted, rather than for prevention of damage that may occur in the future. Since predicting which species may produce catastrophic effects is difficult, some agencies have, or are moving to, a "pathways of invasion" approach, with the support or direction of specific legislation. There is no known effort to identify additional likely pathways of invasion at this time, however. Finally, little emphasis is placed on preventing the export of species native to the United States to other countries where they are not native (see Box, p.6), even though President Carter's 1977 Executive Order instructed federal agencies to use their existing authorities to do so.
No federal agency appears to serve as a focus for efforts to control or prevent non-native species affecting industries other than the agriculture-forestry sector the clear focus of APHIS. APHIS looks at the major risks to agriculture: shipments of fruits, seeds, vegetables, horticultural specimens (especially with soil), cut flowers, etc. The agency's budget provides inspectors for imports of poultry, fruit, grain, etc., but not for used tires, wooden packing boxes, aquarium fishes, airplane wheel wells, commercial fishery products, and so on, which might introduce species that could threaten electric utilities, irrigation facilities, recreational boating or fishing, etc. Nor is it clear that relevant laws provide authority to carry out such inspections, even if funding were sufficient.
Moreover, while APHIS can regulate imports of plants or animals to this country, it has very little authority to regulate living plants or animals once they are admitted. Most significantly, it does not regulate the release of species into the wild, once they have been admitted, unless the species is already designated a noxious weed or disease earner. It can, for example, inspect imported emus or ostriches for the sake of protecting domestic poultry from foreign diseases. However, the numerous releases of these birds after the markets for these birds crashed suggest that the birds themselves, as non-native species, are regulated by no one. 41 The same may be true for aquarium fishes and horticultural specimens. Hydrilla infestations in Florida and the Potomac, for example, were very likely caused by aquarium hobbyists dumping fish tank contents. It is unclear whether the dumpers violated any state or federal laws, even though their acts resulted in hundreds of millions of dollars of private and taxpayer costs.
Finally, APHIS does not regulate the commercial sale of species that are already well-established. Purple loosestrife, Norway maple, and English ivy continue to be widely sold in commercial nurseries, and even though all are important pests their sale does not violate federal law. (See discussion of purple loosestrife, below, for example.) The sale of some of these plants is forbidden in some states, but the plant could be purchased legally in one state and then moved to another, thereby obviating the protection of the second state's laws. 42 While these species spread naturally, their sale in nurseries offers new opportunities to introduce such species in entirely new areas where they are not currently found, even as expensive control efforts occur in other parts of their range.
Similarly, FWS does not have authority to provide general protection for the country's ecosystems. It could not stop an African game fish, for instance, from being released in the bayous of Louisiana or the mountain streams of Wyoming on the mere presumption that it would unbalance local ecosystems if the fish were to spread. Only if FWS knew that the species might harm a species protected under ESA would it have clear authority to stop the importation and release. Similarly, if there were an effort to import a new grass to improve forage on National Grasslands, it is unclear that FWS could prevent the release of the species on general ecological grounds. NMFS has even less regulatory authority, since its responsibilities for inland waters are limited, and largely confined to demonstrable effects on anadromous species protected under ESA.
One option not provided under current law could address the intentional release of non-native species. A review panel of experts from various disciplines could be empowered to review releases by governments at any level or by non-governmental sources into any environment in which they are not native. While such a panel would have done nothing to control the release of hydrilla into the Potomac, for instance, it could provide a brake on the release of exotic grasses by federal agencies to improve forage or of non-native game fishes into new drainages. The use of the expertise of federal and other scientists and managers, if it prevented only a few introductions such as melaleuca or mongooses, could be a cost-effective option that Congress may wish to consider.
Under a single species approach, plants or animals must be placed on a black list before they are regulated as harmful. Harm can rarely be demonstrated unless the plant or animal is already at pest levels and inflicting damage, i.e., generally after the species is reproducing and spreading. Several examples of this approach are extant in law: coverage of the brown tree snake under NANPCA (which otherwise regulates the pathway of ballast water), coverage of most non-native birds under the WBCA (although the purpose is to protect the birds themselves in their natural environment, not the U.S. environment), and the requirement that individual weed species be listed on an exclusion list before they can be regulated under the Federal Noxious Weed Act. As noted, exclusion lists generally require damage to be severe enough to be readily apparent before protection (much less prevention) can begin.
There are a few instances of regulation and prevention by pathway. Among the most comprehensive has been NANPCA, as amended by MSA. Its focus is on ballast water as a risk to both saltwater and freshwater ports, bays, and estuaries. Its goals put prevention on an equal or higher footing than control of species that are already established. It requires the participation of several federal agencies, conducts research, and implements regulations on the mid-ocean exchange of ballast water and various other measures to prevent non-natives from entering U.S. ports.
Below is a discussion of selected harmful non-native species, with emphasis on their economic impacts (where known), the affected industries or interests, the origin of the species, its means of introduction to this country, and its effects on natural ecosystems. Species are selected on the basis of past congressional interest, amount of economic damage, availability of information, and ability to illustrate the range of problems associated with introductions of non-natives. (Beneficial non-natives are not included.) Comparatively recent arrivals are emphasized over long-term nonnatives. Species are grouped by taxonomic affinities: microorganisms, plants, insects, other arthropods, mollusks, and vertebrates.
Whirling Disease, Myxobolus cerebralis. Whirling disease is a protozoan parasite that affects the nervous system of trout species. This parasite has a two-host life cycle fish and a common aquatic worm. A free-swimming stage enters young trout where it attacks their cartilage. This parasite was first introduced to the United States from Europe in the 1950s, probably in infected trout. The disease spread as these infected trout were distributed among hatcheries or were stocked in open waters. This disease now occurs in the wild in 11 states. While whirling disease is not a major problem in eastern states, it is severe in some western states, and has decimated trout populations. So far its severe damage has been primarily to wild rainbow trout, although other salmonid species can become infected. The rainbow trout population in the Madison River (MT) has declined by 90% since the introduction of whirling disease. Although several states are spending tens of millions of dollars annually to control whirling disease, no national or international cost estimates were found for damages caused by this species. In the 104th Congress, Sen. Baucus introduced S.1019, to direct the Fish and Wildlife Service to examine the impacts of whirling disease, and other parasites and pathogens, on trout in the Madison River, and similar natural habitats. No action was taken on this measure. No new bills have been introduced. For more information, see: http://www.montana.edu/wwwrc/docs/whirling/centerpage/whiring.html and http://www.whirling-disease.org/whirling/FAQ.html.
Leafy Spurge, Euphorbia esula. This aggressive invader is native to Eurasia and was brought to this country in 1827 in contaminated seed. 43 It is now found throughout the contiguous United States except for the southeast. In open areas of pasture or rangeland, it crowds out other vegetation, and at concentrations above 10-20% cattle will not graze in infested land, thereby causing precipitous drops in land values, and a loss of agricultural jobs. Biocontrol is being used in some areas, with 13 insect species known to attack the plant. The federal role has included USDA research on control methods, and estimates of economic impacts. States have their own major control programs, some funded by a cost-sharing program among states, local governments, and landowners. Direct and indirect economic effects of this species alone are estimated at hundreds of millions of dollars. 44
Purple Loosestrife, Lythrum salicaria. This wetland invader was imported from Europe in the early 1800s for its medicinal value and for the beautiful purple spikes of the blooming plant. Unsuspecting visitors to an infested wetland often admire the beauty of the marsh when L. salicaria is in bloom, unaware that it has crowded out native plants and animals. Its vegetative dominance may increase the likelihood of listing additional native species under the ESA. Interestingly, this species is still sold as an ornamental in nurseries in some states, though 24 states have listed it as a noxious weed and prohibit its sale. It is found in 42 of the contiguous states, and could well invade the remaining six. The plant is extremely difficult to eradicate, and control has focused on preventing its spread or establishment. Estimated losses are $45 million per year in control and forage loss. 45
Yellow Star Thistle, Centaurea solistialis. This pest was introduced in the early 1900s, apparently as a contaminant in alfalfa seed. It is native to southeastern Europe. The flowers have stiff spines that can injure humans or livestock; they may grow in such dense stands as to prevent foot travel. It is found in much of the west, although the plant appears to have been eradicated in Montana. It is still spread via contaminated seed; recreational vehicles are a newer means of transport. The species is most common in California, where it covers an estimated 8 million acres greater than the area of Maryland and Delaware combined. Economic impacts are unknown, but native vegetation is crowded out where the plant is common.
Water Hyacinth, Eichhornia crassipes. This freshwater aquatic plant originally came from South America, and forms impenetrable mats of floating vegetation (as much as 200 tons per acre). It was believed to have been introduced to the United States at the World's Industrial and Cotton Centennial Exposition in Louisiana in 1884-1885, after which a Florida visitor returned home and released the plant into the St. Johns River, east of Orlando. Currently its range includes California and most southern states. Water hyacinths clog flood-control and irrigation systems, provide habitat for disease-carrying insects such as mosquitoes, and prevent boats from moving on waterways. They also drastically reduce the diversity of native aquatic species, lower dissolved oxygen levels in the water so that fish die, accelerate the rate at which bodies of water fill in, and prevent fish from spawning by covering spawning beds. U.S. annual expenditures to control aquatic weeds (most of them non-natives, such as water hyacinth) are reported to be $100 million. 46 For more information, see: http://aquat1.ifas.ufl/edu/hydcirc.html and http://www.wa.gov/ecology/wq/plants/weeds/aqua010.html.
Hydrilla, Hydrilla verticilla. This freshwater aquatic plant originally came from Asia and has become the most abundant aquatic plant in Florida, where it grows in thick surface mats and displaces native vegetation. This plant was imported into the United States in the early 1950s for use in aquariums, and was likely discarded into the wild near Tampa and Miami. A subsequent introduction occurred in the Potomac River basin. Distribution in the United States now ranges from Connecticut southward along coastal states to Texas as well as on the west coast in California and Washington. Several inland states Pennsylvania, Tennessee, and Arizona also have populations. Generally, this species is most likely to spread when plant fragments are carried along with recreational boats into new habitat.
Hydrilla causes major problems with water use. In drainage canals, it greatly reduces flow, which can result in flooding and damage to canal banks and structures. In irrigation canals, it impedes flow and clogs intakes of irrigation pumps. In utility cooling reservoirs, it disrupts flow necessary for adequate water cooling. Hydrilla can interfere with recreational and commercial vessel navigation. In addition to interfering with boating by fisherman and water skiers, hydrilla hampers swimming, displaces native vegetation communities, and can damage sportfish populations. The economic losses in these water use values to property owners, tourists, and users can be staggering. U.S. annual expenditures to control aquatic weeds (most of them non-natives, such as hydrilla) are reported to be $100 million. 47 In the 99th Congress, P.L. 99-662 included a provision directing the Secretary of the Army to study the feasibility of eradicating and controlling hydrilla in the Potomac River. For more information, see: http://nas.er.usgs.gov/monocots/hy_verti.html.
Formosan Termite, Coptotermes formosanus. The Formosan subterranean termite is native to east Asia. It is known to have spread to Sri Lanka, Hawaii, South Africa, and the southeastern United States. Its spread probably began with the return of various tankers and cargo ships after World War II, returning cargo probably rested on or in infested packing material and pall ets. The major threat posed by this species went unrecognized for over 20 years, although a few scientists tried to sound the alarm. 48 The species now exists from California to Florida and north to Virginia, with ideal habitat being found particularly in the humid Gulf Coast area. The species does not exist where winters are more severe. In very dry areas a source of water, such as a leaky pipe, is essential. Spread of the colonies appears to be primarily by human transport of infested wood or soil. (The winged queens and kings are very weak fliers.)
The termites are extremely destructive and colonies eventually have millions of workers and soldier termites. Severely infested structures will collapse a stage that is reached more quickly with this species than with domestic species of termites. When living trees are infested, treatment is extremely difficult, since pesticides on the surface of the tree have very little effect on the termites inside the damaged tree. Destruction of trees in New Orleans is severe, leaving some streets virtually bare of trees. Damage from the species, plus the cost of treating infected buildings and trees is estimated in the hundreds of millions of dollars annually in New Orleans alone, and about $1 billion nationwide. 49
The already widespread distribution of this species combined with the severe difficulty in treating for it means that its major limiting factor may be its relative intolerance for lower temperatures or lower humidity. To a limited extent, central heating and dense construction may allow it to invade heated buildings in colder states. The current focus of the federal government is on treatment and methods of control, more than on the prevention of new importations of a species that is already widely distributed. For FY1998, a special appropriation of $5 million to coordinate the federal response was added for the Agricultural Research Service, whose program is described at http://www.ars.usda.gov/is/fullstop/.
Fire Ant, Solenopsis invicta. Fire ants first entered the United States from Argentina through the port of Mobile, Alabama, perhaps as early as 1918. Since then, they have spread through much of the southeast, reportedly as far north as Tennessee and southern Virginia, and west into Texas. A few colonies have been found in New Mexico, and it is feared that they may be established in a limited area in California. The species develops very large surface-dwelling colonies in disturbed areas such as pastures and lawns. While the sting of the individual ant is less severe than that of many other insects, the fire ant colony's habit of swarming quickly up the leg of any animal that slows briefly near a nest has earned the species a ferocious reputation. In severe cases, sensitive individuals (human and otherwise) may die from the stings. Some agricultural areas are severely hampered with high levels of infestation. In residential areas, people complain of being unable to use their yards, or allow their pets outside. Estimated damages to livestock, wildlife and public health in Texas alone are $300 million annually; and $2 billion per year nationally. 50
Argentine Ant, Linepithema humile. Argentine ants (until recently called Iridomyrmex humilis) have been present in the United States for about a century. These tiny ants are common household pests in most parts of the country, including Hawaii. Their sting is negligible except to unusually sensitive persons. The ants can enter very small openings to take food from all but the most tightly sealed containers. They can be serious garden and orchard pests due to their habit of guarding aphids and certain other plant pests and feeding off of the honeydew produced by these insects. The guarded pests are thereby able to increase their populations to levels much more likely to damage the host plants. In optimum habitat, colonies of Argentine ants can reach 300,000 ants in colonies with multiple queens capable of laying thousands of eggs per day. They out-compete most other native ant species for food sources. Even that other major ant invader, the fire ant, may find itself starved out of an area, due to the efficiency of the Argentine ant. In turn, populations of lizards, frogs, and other organisms that feed on native ants may plummet.
Economic effects fall primarily on commercial crops, from oleander to oranges. Homeowners are affected as well. To the extent that the Argentine ant reduces populations of animals (e.g., through competition) or plants (e.g., through displacing a plant species' closely adapted pollinators, or allowing plant pests to increase), the species could cause some species to be listed under the Endangered Species Act, thereby increasing regulatory burdens on affected parties. In the 105th Congress, Sen. Gramm introduced S.932 to establish a National Advisory and Implementation Board on Imported Fire Ant Control, Management, and Eradication to provide grants for research or demonstration projects related to the control, management, and possible eradication of imported fire ants; the bill was not acted on. For more information, see http://www.hear.org/hnis/index.html#LinHumI01.
Africanized Honeybee, Apis meillifera scutellata. This subspecies of honeybee is an extremely close relative of the European honeybee, familiar to beekeepers around the country. 51 Neither subspecies is native to North America but the European honeybee is one of the arrivals to North America whose benefits in crop pollination are thought to outweigh the detrimental impact on population levels of native species of bees. 52 The sting of both subspecies is equal in severity, and worker bees of both species die as the result of stinging. Africanized bees are far more likely to attack, and attack in greater force, than their calmer European sisters. This reduced threshold for aggression poses dangers for humans, pets, domestic animals, etc., who may wander unknowingly past a nest, and for commercial beekeepers who find it far more difficult to manage their hives, move them to commercial orchards for pollination services, etc.
After an accidental escape from research colonies in Brazil in 1957, the species spread north and reached the U.S. border about 10 years ago. In the southern United States, a few very serious attacks (including at least four human deaths) have occurred. Current control efforts have fallen heavily on the beekeeping industry, which has had to supply new European queens to maintain the stability of working colonies. The economic impact has been an added blow to beekeepers (and therefore orchardists) suffering from other serious pests such as bee mites. (See below.) In a touch of environmental justice, however, these same bee mites attack Africanized bees as well as European bees, and the mites may be one reason why Africanized bees (unprotected in the wild by human keepers) are expanding their U.S. range somewhat more slowly than expected. The increased costs of control measures will affect the cost of pollination services, reduce the number of beekeepers, and ultimately increase food costs for the crops (from alfalfa to oranges) that require pollination by bees.
Asian Long-Horned Beetle, Anoplophora glabripennis. The Asian long-horned beetle has done much in recent months to increase awareness at the highest levels of government of the threats posed by the introduction of non-native species. This species has been reported in New York state and the area around Chicago. It appears to have arrived in packing materials or pallet wood from China, but is also native to Japan and Korea. It is considered an important threat to trees in its native range, and an even more serious threat elsewhere. In China, it attacks elms, poplars, and willows, among other species. In this country, it attacks a broad range of species, including willow, poplar, birch, rose of Sharon, horsechestnut, and most maple (Acer) species norway, red, sugar, silver, boxelder, and sycamore maples) and many others. The species spreads slowly, and may infest a tree for years before the tree is sufficiently weakened to cause death. Because the larvae live deep within the tree, treating the living tree by spraying pesticides on its bark is ineffective. Cutting infested trees and complete destruction of all living wood is currently the only practical treatment. Unfortunately, to prevent spreading the beetle, nearby trees, often showing no signs of infestation, must be destroyed as well. In addition to the esthetic loss, the loss of urban trees would contribute to increased heating and cooling costs for homeowners due to the loss of shading and windbreaks.
The destruction of most of an infested neighborhood's trees has caused serious concern at all levels of government in areas when this beetle now exists. Industries such as furniture-making, maple syrup, and tourism are deeply concerned about the threat of this beetle to their raw materials, Introduction of this species has been compared to the introduction in the late 1800s of chestnut blight (which has virtually destroyed a dominant tree species in eastern forests and removed a major food source for many animals as well as an important ornamental tree for residential areas), or of the gypsy moth by a French astronomer then working at Harvard University.
In response to the threat posed by these beetles, APHIS issued an emergency regulation (7 CFR 319.40) prohibiting imports of untreated solid wood packing material from China. The regulation became effective Dec.17, 1998. It requires solid wood packing material from China to be treated in any of several specified methods (including fumigation with methyl bromide) to kill this and other pests, and required shipments from China to pay an inspection fee to cover the costs of these services. Other countries in eastern Asia also harbor this beetle, but were not included under the regulation. These regulations will reduce the chance of importing other species of pests from China that may inhabit solid wood. Since treatment will increase costs to export their products to the United States, China objected to the regulation and threatened a trade war. Environmentalists also objected to the inclusion of fumigation with methyl bromide (a contributor to atmospheric ozone depletion) as an acceptable treatment option. Many observers cite this controversy as contributing to much greater attention at higher levels of government to problems created by the proliferation of non-native species. For more information, see: http://www.aphis.usda.gov/ppq/1onghorn.htm or http://www.fs.fed.us/news/today/Dec98/Dec198-01.htm.
Asian Tiger Mosquito, Aedes albopiclus. This mosquito is thought to have arrived in tires imported from Asia for re-treading over 15 years ago. Its larvae are able to survive in almost any standing water, from backyard dog dishes to cemetery flower pots. Unlike most mosquitoes, this one is diurnal, making it more likely than other mosquitoes to bite (largely diurnal) humans. The species can carry encephalitis, dengue fever, dengue hemorrhagic fever, yellow fever, and several other diseases. The Centers for Disease Control (CDC) initially was concerned that the species could spread epidemics, but so far major epidemics have not occurred. This prolific breeder has made some areas of the south central and Gulf coast states very unpleasant when its populations reach their highest densities. People must wear masks in some sites to avoid inhaling clouds of mosquitoes, and calves have choked on them.
Economic impacts so far have included higher costs for mosquito control programs in humid areas. Its possible medical threat is a more complex question. Failure to spread diseases so far has been a complex issue related to the biology of the viruses, the mosquito, and the host. The insect's broad range of meal sources reduces transmission of most diseases: if it picks up yellow fever, for example, it will not transmit it to a human if its next meal is mouse blood. And a female mosquito may bite only a handful of times in her short adult life. In another odd twist, it may be that the larvae of this mosquito are out-competing the larvae of an introduced close and dangerous cousin, Aedes aegypti, a very efficient transmitter of yellow fever. The tiger mosquito may also be able to transmit canine heartworm.
The CDC, responding to the public health threat, took steps to require the disinfection of imported tires. No disinfection of exported tires is required. As a public health matter, this disparity is unfortunate, since difficult sanitation conditions and reduced health care make the transmission of disease by this species far more likely in other countries than in the United States. Innovative control efforts include attempts to educate young students to spot and eliminate (usually by simply emptying) breeding sites.
38 OTA Report, p.163.
39 History does not provide grounds for optimism that the new Order will be implemented: the OTA report notes (p.166) that the previous order of 1977 in practice... has been ignored by most Federal agencies. Moreover, the Fish and Wildlife Service has yet to implement the order in regulations although specifically directed to do so." Opposition to proposed FWS regulations came primarily from agriculture, zoos, game ranches, aquaculture, and the pet trade. A revised version was opposed Strongly by the hobby fish industry. The OTA report also notes that at that time no major industry supported the proposed FWS regulations. With greater recognition of the threat from non-natives in the intervening six years, support for regulations may have increased.
40 be authors in the course of their research discovered no instances of control measures on a well-established species leading to eradication, with the exception of smallpox. For established species, eradication is extremely improbable. For very recent arrivals, it could be possible. In contrast, prevention (here including a reduction in the number of non-natives establishing breeding populations each year) could prove quite feasible.
41 If they reach pest levels, the Animal Damage Control program within APHIS can take Steps to control pest populations.
42 There is a parallel with the state waterfowl hunting laws in the early 20th century. States with restrictive, conservation oriented laws were literally out-gunned by states with more permissive laws when the waterfowl migrated through several states. Pressure from state governments (and their hunters) seeking to put all states on an equal footing in the burden of conservation was a significant factor leading to federal migratory bird hunting laws.
43 All of the plants described in this report are covered in the comprehensive FICMNEW report. Appendices cover major relevant laws, both federal and state. Major invasive species are analyzed, as are the effects on different habitat types. Substantial information, particularly on the history of the plant invasions cited here, was drawn from this report.
44 FICMNEW, p.26-28.
45 Pimentel, et al.
46 OTA Report, p. 67.
47 OTA Report, p. 67.
48 One of these scientists, Jeffery LaFage, an entomologist from Louisiana State University, had just begun an effort to support treatment in the historic French Quarter of New Orleans when he died in 1988. The French Quarter is now probably the most highly infested area of the Gulf, due to the favorable climate and the architecture of the area.
50 U5A Today. "Deadly southern fire ants are on the move." USA Today. Dec.15, 1998. p. USA.
51 The name "killer bee" has been abandoned by most experts because of the hysteria and panic it induces. Instead, "Africanized bee" is now accepted by entomologists as a name with a more neutral emphasis on both its geographic origin and successful adaptation to local conditions. In Europe, honeybees have been kept over millennia; in the process, beekeepers naturally selected for unusual gentleness. Bee colonies have not been kept in Africa until relatively recently, and natural selection favored those wild colonies able to defend themselves most aggressively from attack.
52 Most native North American bees (e.g., carpenter bees and sweat bees) are solitary, and many play an important role in pollination of wild plants and some crops (e.g., squashes, watermelons, and cantaloupes). Where honeybee populations are high, competition can reduce populations of native bees; where mites have reduced populations of honey bees, native bees are increasing.
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