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In an Environmental Risk Analysis (ERA) benefits and risks of a biocontrol agent (BCA) or other beneficial organisms are assessed using criteria based on ecological determinants such as the potential and impact of establishment and dispersal, on known and new hosts (host range vs. specificity) and direct and indirect non-target effects. There is a wide variety of natural enemies used for biocontrol, each of which has its specific biological and ecological requirements. In regulatory requirements for regulation and registration of non-native agents, assessment of host specificity is one of the main criteria in evaluating risks. Establishing a generalist’s potential host range in a new area is one of the most challenging issues to be assessed prior to its introduction and release. Thus, generalist predators and parasitoids are often excluded a priori from being licensed. Here we will discuss several examples of different taxa with a generalist host range and show that each of them has specific requirements and as a result require a specific risk assessment of their own.

Due to typesetting errors, Table 5 was not displayed correctly in the initial online publication. The original online article has been corrected.

In the past 100 years many exotic naturalenemies have been imported, mass reared andreleased as biological control agents. Negativeenvironmental effects of these releases haverarely been reported. The current popularity ofinundative biological control may, however,result in problems, as an increasing number ofactivities will be executed by persons nottrained in identification, evaluation andrelease of biological control agents.Therefore, a methodology for risk assessmenthas been developed within the EU-financedproject `Evaluating Environmental Risks ofBiological Control Introductions into Europe[ERBIC]' as a basis for regulation of importand release of exotic natural enemies used ininundative forms of biological control (i.e.not in `classical biological control' thoughsome of the same principles and approachesapply). This paper proposes a general frameworkof a risk assessment methodology for biologicalcontrol agents, integrating information on thepotential of an agent to establish, itsabilities to disperse, its host range, and itsdirect and indirect effects on non-targets. Ofthese parameters, estimating indirect effectson non-targets will be most difficult, asmyriads of indirect effects may occur whengeneralist natural enemies are introduced. Theparameter `host range' forms a central elementin the whole risk evaluation process, becauselack of host specificity might lead tounacceptable risk if the agent establishes anddisperses widely, whereas, in contrast, amonophagous biological control agent is notexpected to create serious risk even when itestablishes and disperses well. Drawing onpublished information and expert opinion, theproposed risk assessment methodology is appliedto a number of biological control agentscurrently in use. These illustrative casehistories indicate that the risk assessmentmethodology can discriminate between agents,with some species attaining low `risk indices'and others scoring moderate or high. Riskindices should, however, not be seen asabsolute values, but as indicators to which ajudgement can be connected by biologicalcontrol experts for granting permission torelease or not.

Improved laboratory methods are described in detail for mass rearing of various thrips species, such as Frankliniella occidentalis, Frankliniella intonsa, Thrips palmi, Thrips tabaci (Thysanoptera: Thripidae) and a thrips parasitoid, Ceranisus menes (Hymenoptera: Eulophidae), using various foods. In one method, plant pollen and honey solution are used as food sources. In a second method, germinated broad bean seeds are used. Eggs, produced in large numbers in water, are collected by a suction funnel onto a filter paper and incubated in a Petri dish. Large numbers of larvae that hatch are collected by using food traps (plant pollen). Larvae can be reared on pollen or on germinated broad bean seeds until adult emergence without additional water and food. This method has been found useful for producing even-aged thrips at different densities (up to 500 larvae in a cage of 80 mm diameter) with relatively low mortality rates. Evaluation of this rearing method for F. intonsa, shows that during 2 weeks at 20 ◦ Cp er 100 females more than 4000 females could be produced in the next generation. About 5 min per day is required to achieve this productivity of mass production. The method is also suitable for producing large numbers of the solitary endoparasitoid of thrips larvae, C. menes.

The life history of the endoparasitoid, Ceranisus menes (Walker) (Hymenoptera: Eulophidae) was studied in the laboratory on Frankliniella intonsa and western flower thrips (WFT). Parasitoid development and reproductive capacity depended on temperature. Development is synchronized with larval development of the host and is faster on WFT than on F. intonsa. There is a marked variation in pupal duration of C. menes at 20 and 25°C. Average longevity of C. menes did not differ between WFT and F. intonsa at 25°C. Fecundity was 2.5 times as high with WFT as hosts than with F. intonsa. The intrinsic rate of increase (r m ) of C. menes on WFT was higher than that on F. intonsa at both temperatures, but was lower than those of the thrips hosts. It is suggested that multiple releases will be needed to control F. intonsa or WFT outbreaks.