Control Of Exotic Species And Its Implications

Control of exotic species is a goal of natural resource managers and conservation biologists. Many methods are available, ranging from quarantining in order to keep them out to eradication so as to remove them once they are established (Dahlsten, 1986; Dahlsten and Garcia, 1989; Groves, 1989; Reichard, 1997; Schardt, 1997; Simberloff, 1997). Eradication in particular is usually difficult and often unpleasant work, but in some cases such as in national parks, it is necessary. As noted by Temple (1990),

In spite of all that is known about the negative influence of exotics and the obvious conservation benefits of controlling them, their eradication inspires little enthusiasm among most conservationists, the public, or governments. Reasons for this apathy include misconceptions about the nature and magnitude of the problem, fears of the negative public reactions that almost invariably accompany eradication efforts, espe-

Chemical Pesticides

FIGURE 7.6 Succession of pest control paradigms that started after World War II with chemical pesticides.

Chemical Pesticides

FIGURE 7.6 Succession of pest control paradigms that started after World War II with chemical pesticides.

cially for animals, and intimidation by the inefficient labor-intensive nature of current eradication technologies.

These challenges need to be addressed if exotic control is to be a realistic goal. To meet the challenges Temple (1990) calls for "a better job of educating the public about the threats of exotics," the development of "more palatable methods of eradication that avoid issues of ethics or cruelty," and the recruitment of "scientists whose research will produce new approaches for controlling or eradicating exotic species." This is a call for creative research on control methods that will occupy increasing numbers of applied ecologists in the future.

Foundations of exotic control rest on the long history of pest control, especially in agriculture and forestry in terms of diseases, weeds, and insects. A tremendous amount of knowledge has accumulated on the subject over a long history. However, modern pest management essentially dates from after World War II when agricultural production and pesticide use expanded greatly. A succession of paradigms has emerged (Figure 7.6) but pest problems continue to accelerate. The consensus is that eradication is often impossible, and even control is difficult. At best some form of management is the most reasonable goal (National Research Council [NRC], 1996b). The primary tools for controlling many exotic species are still chemical pesticides, which have positive and negative aspects (Table 7.3).

While the environmental and social costs of pesticides in agriculture and forestry are becoming better understood (Pimentel et al., 1980, 1992), pesticide use continues to increase. Embedded in these pest control systems is an ironic feedback circuit, termed the pesticide treadmill (van den Bosch, 1978). In this circuit greater use of

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