Insect biological control and non-target effects: a European perspective.

Abstract

A 4-year research project on 'Evaluating Environmental Risks of Biocontrol Introductions in Europe' (ERBIC) is described, and early results are presented. The project focuses on arthropod biological control (using both microbial and macrobial agents), and uses literature review, case studies with empirical work and various types of modelling to illuminate risk to non-target organisms. These methods will hopefully lead to the development of usable methodologies and guidelines for risk assessment in arthropod biological control, by the project's completion in 2002. Reviewing existing published and unpublished data on the classical biological control of insects (a first step in this project) has revealed that for only 1.5% of introductions is there some data regarding the realized field specificity of the agent. For a tiny proportion of introductions there are quantitative data regarding mortality in non-targets. From these cases, with some extrapolation, we can deduce that 10% or less of classical biological control introductions in the past led to population changes in non-targets. Data on population-level effects from simulated uses or trials suggest that 49% of inundative or augmentative uses of agents led to (local, short-term) population changes for non-targets. Case studies into: (i) exotic specialist parasitoids used in the greenhouse; (ii) exotic generalist parasitoids used inundatively in the field; (iii) exotic generalist predators used inundatively; and (iv) fungi and nematodes used as bioinsecticides, are outlined. The results so far demonstrate: (i) the apparent safety of Trichogramma (generalist parasitoid) releases in Switzerland, despite rare species within its host range; (ii) the lack of overwintering capability in northern Italy in one generalist predator (Orius insidiosis), but its presence in another (Harmonia axyridis); (iii) little evidence that the predation of certain stages of native predators by introduced predators will enhance environmental risks in the cases in question; and (iv) the apparent safety of bioinsecticide releases of particular pathogen strains for important naturally occurring predators when exposed directly or by feeding on infected prey.

Biological control and sustainable food production

“…As a generalization, a strong case can be made for the view that biological control contributes to a reduction in pesticide use with corresponding benefits to the environment. While it should not be assumed that introduced biological control agents pose no risk to native species and ecosystems, history suggests that there have been remarkably few problems, even through the many decades when regulation was virtually non-existent (Lynch et al 2001;van Lenteren et al 2006a). The recently published regulatory guidelines are intended to produce a careful analysis of the establishment potential of an imported species in a new environment and any adverse effects on non-target organisms and ecosystem functions that may then arise.…”

“…Pre-release screening of entomophagous biological control agents lagged behind their weed counterparts until the warnings by Howarth (1983Howarth ( , 1991 and Lockwood (1993), which raised concerns about possible impacts on non-target species. Interestingly, an analysis of published and unpublished information found that only 1.5% of entomophagous biological control agents introduced before 1999 had undergone any pre-release host specificity testing (Lynch et al 2001). Yet, despite the fact that non-target effects of entomophagous biological control agents were rarely considered prior to import and release, there are only a few known cases where any adverse effects can be attributed to the release of such organisms (van Lenteren et al 2006a).…”

Dark clouds and their silver linings: exotic generalist predators in augmentative biological control

“…Many exotic natural enemies released in European greenhouses are unlikely to survive winter, but some may. For instance, a research program funded by the European Union established the lack of overwintering capability in the nearctic generalist predator Orius insidiosus (Say) in Italy, but indicated that the Asian lady beetle H. axyridis may successfully overwinter in that area (Lynch et al 2001). Certainly, overwintering ability of an introduced species may depend upon the geographic origin of the strain used.…”

“…Some even fear that introductions of nonindigenous natural enemies for biological control may have already caused extinctions of target and nontarget organisms. However, there is some dispute as to the validity of the evidence brought forward to prove the harmful side-effects of biocontrol introductions (see and Howarth 2001 for conflicting views; see also Lynch et al 2001 for an overview of the evidence). In short, despite the massive numbers of non-native natural enemies that have been released in classical and augmentative biological control programs, there is no unequivocal evidence that introduced arthropods have been the direct cause of species extinctions.…”

Effects of mass releases of Trichogramma brassicae on predatory insects in maize

“…Non-target effects have become important in insect biological control projects over the past decade, and several review papers have addressed this issue (Howarth, 1991;Simberloff & Stiling, 1996;Stiling & Simberloff, 2000;Lynch et al, 2001). Non-target effects may arise if either non-target herbivores or natural enemies present in the habitat are attacked by the biological control agent.…”