Pros and Cons of Biological Control

DOI: 10.1007/978-3-540-36920-2_23


This chapter will briefly review the positive aspects of biological control and will highlight a few examples. It will further
review negative aspects of biological control introductions. One of the examples where biological control led to detrimental
environmental effects was the introduction of the ladybeetle Harmonia axyridis, and this case will be outlined in more detail. This example will also be used to explore some of the population biology
mechanisms which can contribute to the net effects of introduced natural enemies. Finally, some information on recent developments
and improvements in risk assessment of biological control agents is provided.

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    • "The probabilities associated with the sets of risks could then be set from two kinds of intense research: research aimed at determining the likelihood of an imported biological control agent causing nontarget effects and research aimed at determining the likelihood of native species being unable to control the target (Paini et al ., 2008). Otherwise, we may stray into trying to balance the benefits of action against the costs of action (Babendreier, 2007), which we do not consider to be very productive in improving the decision-making process. "
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    ABSTRACT: 1 Florida has an exceptional burden of invasive species. The history of the classical biological control of invasive arthropod pest species in the region largely is one of inadequate pre-release testing for nontarget effects. 2 A recent analysis indicated that a substantial risk of nontarget effects may exist in Florida, although the risk appears to be confined to a relatively small group of species within approximately ten families and documented cases of nontarget effects are rare, despite previous risky practices. 3 Great progress has been made recently in creating an organized framework for dealing with the uncertainty accompanying biological control importations in Florida and elsewhere. We suggest some ways in which balancing the risks and associated costs of releasing a biological control agent against the risks and associated costs of not releasing the agent may be improved. 4 Ultimately, experts will need to set some level of acceptable risk, and the 'precautionary principle' has been advanced to guide this process. As it stands, however, the precautionary principle applied to biological control falls short as a guide because it does not provide a prescription for action. 5 Florida case histories clearly illustrate both the complexity and urgency related to developing a prescription for action.
    Preview · Article · Feb 2010 · Agricultural and Forest Entomology
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    • "2005) and is frequently used as one of the main justifications for classical biological control programs (Mitchell & Power 2003; Hajek 2004). Although most of these programs have failed (Babendreier 2007), the few that have been successful have frequently been regarded as evidence supporting the enemy-release hypothesis (Crawley 1987; but see Keane & Crawley 2002). To date, the strongest support for the enemy-release hypothesis comes from biogeographical studies that compare infestation or damage by enemies between native and invasive populations of the same species (Colautti et al . "
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    ABSTRACT: Summary 1. During the last centuries many alien species have established and spread in new regions, where some of them cause large ecological and economic problems. As one of the main explanations of the spread of alien species, the enemy-release hypothesis is widely accepted and frequently serves as justification for biological control. 2. We used a global fungus-plant host distribution data set for 140 North American plant species naturalized in Europe to test whether alien plants are generally released from foliar and floral pathogens, whether they are mainly released from pathogens that are rare in the native range, and whether geographic spread of the North American plant species in Europe is associated with release from fungal pathogens. 3. We show that the 140 North American plant species naturalized in Europe were released from 58% of their foliar and floral fungal pathogen species. However, when we also consider fungal pathogens of the native North American host range that in Europe so far have only been reported on other plant species, the estimated release is reduced to 10.3%. Moreover, in Europe North American plants have mainly escaped their rare, pathogens, of which the impact is restricted to few populations. Most importantly and directly opposing the enemy-release hypothesis, geographic spread of the alien plants in Europe was negatively associated with their release from fungal pathogens. 4. Synthesis. North American plants may have escaped particular fungal species that control them in their native range, but based on total loads of fungal species, release from foliar and floral fungal pathogens does not explain the geographic spread of North American plant species in Europe. To test whether enemy release is the major driver of plant invasiveness, we urgently require more studies comparing release of invasive and non-invasive alien species from enemies of different guilds, and studies that assess the actual impact of the enemies.
    Full-text · Article · Feb 2009 · Journal of Ecology
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    • "In any case, given the current adverse impact of H. axyridis in other European countries and North America, (Koch 2003, Koch et al. 2006, Roy et al. 2006, Babendreier 2007, Eschen et al. 2007, Brown et al. 2008a, b, Koch & Galvan 2008)it would not be wise to continue with field releases of this insect. This has recently been concluded also by scientists working on risk assessment of biological control agents (van Lenteren et al. 2008, Roy & Wajnberg 2008). "
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    ABSTRACT: During 1994 -1999 several hundred thousands of Harmonia axyridis adults were released at various cultivations infested by aphids (citrus, vegetable and bean crops, maize, etc.) or in urban places on ornamental plants in central and southern Greece (mainly Attica and Peloponnessos region) as well as on several islands. During 1995-2007, samplings were conducted in some areas, in spring just before any new releases, in order to determine if H. axyridis overwintered in the field. In spring 1995 (the year that followed the first releases) as well in spring 1996-97 and 2000-07, no presence of H. axyridis was recorded in any of the orchards where the predator had been released. Only in spring 1998 and 1999 small colonies (
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