In recent decades, escalating concerns about the dangers of chemical pesticide use, amid growing demands on global agricultural production, have created a drive toward developing biological methods of pest control. Though often touted as having an environmentally pure record, ecological researchers now believe the apparent absence of environmental problems may reflect more on a shortage of evidence, rather than on a well-documented record of no ill effects.
Peter Kareiva, of the Department of Zoology at the University of Washington and editor of a special feature in the October issue of Ecology, entitled "Contributions of Ecology to Biological Control," explains.
"The rewards from basic biocontrol research have been meager to date, largely because the research is disconnected from its implementation, but also because little attention has been paid to possible ecological risks."
However, with annual expenditures for biological control exceeding $200 million, and an indication that the federal government will encourage more vigorous implementation of biocontrol methods in the future, vast opportunity exists for ecological research to contribute with new efforts, new approaches, and much better science than has previously been used.
Says Kareiva, "In the past, ecologists tended to focus solely on the predator-prey aspect of biological control. Today, however, substantive ecological contributions to biocontrol are likely to focus on a broader array of issues, including the harm that the introduction of non-native predators can cause and the benefits of practicing agriculture in a way that promotes the activities of native predators. In addition, though traditionally viewed as applicable only to terrestrial environments, recent evidence shows that biocontrol also has the potential to become a highly effective solution to some of the recent dramatic pest problems in the marine environment."
For example, promoting an increase in populations of parasitic barnacles may be the best hope for halting the world-wide invasion of the European green crab. After "hitch hiking" its way to the western Atlantic in the early 1900's--most likely with a foreign shipment of commercial marine species--the crab has had a devastating economic effect on shellfish and softshell clam fisheries in New England and Nova Scotia. Though just recently introduced to the coast of central California, West Coast fisheries are likely to suffer similar damage from this non-native species.
Currently, the foremost prospect for controlling the European green crab is a parasitic barnacle which attaches itself to the shell of the crab, eventually infecting its bloodstream. However, researchers stress that, although present evidence suggests the barnacle would be a safe control agent, more research is needed on several fronts, including a determination of how many other marine species would be affected by increasing the barnacle population.
Kareiva believes that in order to practice effective biocontrol in both terrestrial and aquatic environments, the ecological ramifications of biocontrol must be thoroughly researched before being implemented.
Kareiva concludes that, "If the federal government is going to advocate a more serious biological control approach to pest management, we must also ensure that we have a clear understanding of its risks. An emphasis on simply delivering technology, without trying to understand why it sometimes fails and sometimes succeeds, will lead to `hit or miss' pest control with the misses possibly disrupting natural communities far more than they reduce pest populations."
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