Classical biological control for the protection of native ecosystems

Authors: VAN DRIESCHE, R - University Of Massachusetts; Carruthers, Raymond; Center, Ted; Smith, Lincoln

Submitted to: Biological Control
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/8/2010
Publication Date: 8/1/2010
Citation: Van Driesche, R.G., Carruthers, R.I., Center, T.D., Smith, L. 2010. Classical biological control for the protection of native ecosystems. Biological Control. 54:502-533.

Interpretive Summary: Invasive species are a huge and growing problem in the United States and most other countries around the world. Non-native introduced insects and plants have highly affected both agriculture and the natural environment. This paper summarizes many of the impacts that invasive species have caused in the natural environment and also assesses the status and control impact of biological control as a management technology. Conclusions include, that classical biological control is a powerful tool for suppression of both invasive plants and insects in native ecosystems. It is felt that this technology will play an increasingly important part in ecological restoration because it provides a means to permanently suppress many invaders over large landscapes without long-term resource commitments. As biological control projects unfold, monitoring of changes in pest density, together with responses of native species should be carried out to quantify and document the program’s effects. Since population changes and community responses induced by biological control programs often require long periods (5-20 years) to reach stable end points, governments must be advised accordingly and projects must be planned and funded to cover such time periods. When used in this comprehensive manner, biological control of invasive plants and insects is likely to expand significantly in response to a large backlog and still expanding set of invasive species the associated environmental damages.

Technical Abstract: Native ecosystems and their component species are undergoing catastrophic and irreparable change globally as habitat is destroyed for human use and invaded by species from other biogeographical areas (Simberloff et al., 1997; Cox, 1999; Lockwood et al., 2006). Political solutions may be devised to stop habitat loss, and restraints and economic incentives used to reduce human exploitation of natural habitats. However, damage from invasive species cannot be halted or corrected so easily. While better legislation and detection tools will be paramount in preventing new invasions, once invaders establish, they persist indefinitely and spread to their ecological limits. Reducing damage in small areas with chemical or mechanical control is possible for some species if funds and staff are available for management. But at the landscape level, these tools usually only work if the infested area is small and too isolated for quick re-infestation. Good examples of that approach are the eradication of rats and ants from islands (e.g., Causton et al., 2005; Towns and Broome, 2003). In contrast, most invasive plants and insects cannot easily be eradicated from continents. For landscape level suppression of such species, classical biological control should be considered because it alone can induce affordable, permanent ecological change over large areas. Our purpose in this article is to provide perspective on the value of classical biological control for the restoration of invader-damaged ecosystems or their native component species. Biological control of plants and insects have different histories, with insect biological control being used for much of its first century against insects damaging to crops. Only in the1990s did insect biological control against environmental pests develop as a goal independent of suppressing crop pests (Van Driesche, 1994). In contrast, weed biological control efforts were rarely focused on weeds infesting crops. Rather, invasive plants in water bodies, forests, and grasslands were targeted to preserve products and services provided by nature such as timber, forage or fresh water. But over time, protection of native biodiversity and ecosystem function became the dominant motive for weed biological control. Benefits of biological control in natural areas include preservation of natural ecosystems as sources of products and recreation for human societies. Additionally, such wild areas provide ecosystem services that benefit humankind, such as flood control, fire regulation, and maintenance of healthy soils. Finally, native ecosystems, not zoos or botanical gardens, are the main repositories of the world’s biodiversity and their long term protection is essential. These divisions – products, ecosystems services, biodiversity – are the major parts of this review. Nontarget effects of misguided or improperly executed biological control on native ecosystems have been discussed previously (Howarth, 1991; Simberloff and Stiling, 1996; Lynch and Thomas, 2000; Louda et al., 2003; van Lenteren et al., 2006) and are not repeated here. Rather, we seek to illustrate the strength and scope of classical biological control as a tool for ecosystem restoration, as this approach is perhaps the only feasible tool currently available that is able to repair or reverse damage from invasive species over large landscapes. We anticipate that more biological control projects will be implemented in the future to correct damage from invasive plants and insects to natural ecosystems. This use will require the joint efforts of biological control practitioners, invasion biologists, ecologists, taxonomists, and conservation specialists.