The world is divided into three groups when it comes to invasive species. The first and largest is the group that has no idea, information or opinion about what an invasive species is or may be let alone whether there is reason for concern or not. This largest of constituencies is only interested in non human species when they slither into its bedrooms (pythons), bring disease (tiger mosquitoes), decreases harvest of baseball bats (emerald ash borer) or pulls down power lines (kudzu) needed to stay connected to social media.
The second interest group has decided the information at hand warrants no concern and no focus or allocation of resources or consideration. In some sense this group has decided to live for today knowing that tomorrow will take care of itself as well as any human generations that may come. The third broad constituency, on the other hand, sees a problem and want to prevent what it can and fix what is damaged in order to preserve a future of maximum opportunities based upon present understandings of biological diversity. This last group's invasive species positions are based upon an understanding that human welfare both directly and indirectly depends on the environment, a concept that the first group never thinks about and the presumptions about which the second groups has questions.
Irreversible environmental damage to ecological system resources and services negatively affect future generations' abilities to achieve quality of life goals. The chronic disruption of natural ecosystems caused by human development activities include the introduction and establishment of novel species that replace existing species' relationships and interactions. A major difficulty arises in any effort to assign a value that would allow an easy decision or choice as to what steps to take in regards to an invasive species issue. The challenge is in determining the estimation of the economic value of environmental resources, service or effects, as well as the possible conflicts between the discounting of ecological effects and long-term environmental and sustainability concerns.
In a sense the whole idea of environmental evaluation lead directly to a conflict between the conservation of environmental assets including indigenous species patterns and aggregations versus traditional patterns of economic development such as the clearance of land for agriculture and urban development. To safeguard future generations' access to ecological services, present human activities (development) would seem to require that the present generation restrict the use of scarce ecological resources. But that is pretty much not going to happen in a world staring at human population numbers growing to 9 plus billion within this century.
If an invasive species has not yet made a measurable or economical impact on a field, landscape or natural area, most people ask why spend money on something that has not happened? It is the same problem facing schools versus prisons; why spend money on education of many individuals to prevent crimes of a few when one can wait until a crime is committed and then remove the specific individual from the community as a whole. Of course when it comes to personal health, we rather reluctantly almost get the prevention thing because our mothers told us so. When it comes to consideration of the environment, however, Mother's advice goes out the window.
The first two group's preoccupation with the present results in a cascading series of decisions that extend beyond invasive species inaction. Bridges are not repaired, libraries are closed and research into environmental tools are shut down. USDA-ARS, for example, is closing its Kika de la Garza Subtropical Agricultural Research Center founding in 1935 in Texas along with 9 other locations across the US because it can no longer afford to support the scientific work done there on:
1) Integrated pest management (IPM) of parasites and diseases of honey bee colonies; 2) Biological control methods used to identify and defeat present and potential pest threats to Rio Grande Valley agriculture; 3) Organic farming systems utilizing holistic approaches to healthy and nutritious food production; 4) Quarantine treatments of subtropical fruits and vegetables; 5) Post harvest treatments of produce for disinfestations by non-chemical means; 6) Aerial remote sensing of agricultural problems; and 7) Pesticide tolerance of vegetables, ornamental, and specialty crops for registration labeling and EPA compliance.
Another example of groups one and two unintentional and unplanned collaboration is the budget driven decision by the U.S. Army Corps of Engineers to stop funding its enormously successful Aquatic Plant Control Research Program. The program traces its original to the catastrophic introduction of a non-indigenous aquatic plant, water-hyacinth (Eichhornia crassipes (Mart.) Solms), which rapidly infested the waters of Florida and Louisiana. The elimination of terrestrial and aquatic biological control research is short sighted, foolish and just plain stupid, but reflects a society concerned now with that it can get today not what it will leave for its children tomorrow.
Thus, it comes down to a series of trade-offs as to what to do with invasive species, their introduction, establishment and control. This is pretty much the life of a gardener; a series of morning decisions based on unsatisfactory trade-offs involving resources such as time and money. It also makes the gardener's case that an touch of prevention is worth more than a costly excursion of eradication and control after the fact. But who has time to listen to gardeners anymore?
 Jan Douwe Meindertsma. “Agricultural Research for Development” [accessed December 31, 2011] http://www.icra-edu.org/page.cfm?pageid=ardhome&loginas=anon_e
 David Pearce. 1993. Valuing The Environment: Past Practice,Future Prospect. [accessed December 31, 2011] http://prototype2010.cserge.webapp3.uea.ac.uk/sites/default/files/pa_1994_02.pdf