D. Babendreier

Environmental impact of invertebrates for biological control of arthropods : methods and risk assessment

* Current status and constraints in the assessment of non-target effects, D Babendreier and F Bigler, and U Kuhlmann * Selection of Non-Target Species for Host Specificity Testing, U Kuhlmann, U Schaffner, and P G Mason, Agriculture and Agri-Food Canada * Host Specificity in Arthropod Biological Control, Methods for Testing and Interpretation of the Data, J C van Lenteren, Wageningen University, Netherlands, M J W Cock, CABI Bioscience, Switzerland, T S Hoffmeister, University of Bremen, Germany, and D P A Sands, CSIRO Entomology, Australia * Measuring and Predicting Indirect Impacts of Biological Control: Competition, Displacement, and Secondary Interactions, R Messing, University of Hawaii at Manoa, B Roitberg, Simon Fraser University, Canada, and J Brodeur, Universite Montreal, Canada * Risks of Interbreeding Between Species Used in Biological Control and Native Species, and Methods for Evaluating its Occurrence and Impact, K R Hopper and S C Britch, Agricultural Research Service, USDA, USA, and E Wajnberg, INRA, France * Assessing the Establishment Potential of Inundative Biological Control Agents, G Boivin, Agriculture et Agroalimentaire Canada, U M Kolliker-Ott, FAL Reckenholz, Switzerland, J Bale, University of Birmingham, UK, and F Bigler * Methods for Monitoring the Dispersal of Natural Enemies from Point Source Releases Associated with Augmentative Biological Control, N J Mills, University of California, USA, D Babendreier and A J M Loomans, Plant Protection Service, Wageningen, The Netherlands * Risks of Plant Damage Caused by Natural Enemies Introduced for Arthropod Biological Control, R Albajes, Universitat de Lleida, Spain, C Castane, R Gabarra and O Alomar, IRTA, Spain * Methods for Assessment of Contaminants of Invertebrate Biological Control Agents and Associated Risks, M S Goettel and G D Inglis, Agriculture and Agri-Food Canada * Post-Release Evaluation of Non-Target Effects of Biological Control Agents, B I P Barratt, AgResearch, New Zealand, B Blossey, Cornell University, USA, and H M T Hokkanen, University of Helsinki, Finland * Molecular Methods for the Identification of Biological Control Agents at the Species and Strain Level, R Stouthamer, University of California, USA * The Usefulness of the Ecoregion Concept for Safer Import of Invertebrate Biological Control Agents, M J W Cock, U Kuhlmann, U Schaffner, F Bigler and D Babendreier * Statistical Tools to Improve the Quality of Experiments and Data Analysis for Assessing Non-Target Effects, T S Hoffmeister, D Babendreier and E Wajnberg * Principles of Environmental Risk Assessment with Emphasis on the New Zealand Perspective, A Moeed, ERMA New Zealand, R Hickson, Ministry of Research, Science and Technology, New Zealand and B I P Barratt, * Environmental Risk Assessment: Methods for Comprehensive Evaluation and Quick Scan, J C van Lenteren and A J M Loomans * Balancing Environmental Risks and Benefits: a Basic Approach, F Bigler and U Kolliker-Ott.

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

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

Selection of non-target species for host specificity testing.

We present comprehensive recommendations for setting up test species lists for arthropod biological control programs that are scientifically based and ensure that all aspects of potential impacts are considered. It is proposed that a set of categories, including ecological similarities, phylogenetic/taxonomic affinities, and safeguard considerations are applied to ecological host range information to develop an initial test list. This list is then filtered to reduce the number of species to be tested by eliminating those with different spatial, temporal and morphological attributes and those species that are not readily obtained, thus unlikely to yield scientifically relevant data. The reduced test list is used for the actual testing but can (and should) be revised if new information obtained indicates that additional or more appropriate species should be included.

Consumption of snowdrop lectin (Galanthus nivalis agglutinin) causes direct effects on adult parasitic wasps

Honeydew is a common sugar-rich excretion of aphids and other phloem-feeding insects and represents the primary sugar in many agricultural systems. When honeydew-producing insects feed on genetically modified plants, the honeydew can contain amounts of the transgene product. Here we address whether this route of exposure poses a risk for non-target insects. Three species of parasitic wasps were selected: i.e. Aphidius colemani, Trichogramma brassicae and Cotesia glomerata, all of which are known to use honeydew as a carbohydrate source in the field. Wasps were fed sucrose solutions with varying concentrations of snowdrop lectin (Galanthus nivalis agglutinin, GNA), a protein that has been engineered into crops to confer resistance against homopteran pests and that has been detected in honeydew. Parameters evaluated included gustatory response, longevity, fecundity, progeny emergence and sex ratio. While A. colemani and T. brassicae, but not C. glomerata, were able to detect GNA, this gustatory recognition had no effect on the acceptance of a GNA-sucrose solution. In all three species, GNA ingestion reduced parasitoid survival significantly. However, in respect to fecundity, negative effects were observed for T. brassicae but not for A. colemani. The results suggest that the effect of GNA consumption may depend on the specifics of a parasitoids biology, especially its longevity and its mode of egg maturation.

Methods Used to Assess Non-target Effects of Invertebrate Biological Control Agents of Arthropod Pests

The number of concerns regarding potential non-target effects of invertebrate biological control agents of arthropods has risen over the last decade and an increasing number of studies have since dealt with this topic. Despite some recent international initiatives aimed at providing guidance for risk assessment of biological control agents, detailed methods on how tests should be designed and conducted to assess for potential non-target effects still need to be provided. It is believed that this review comes at an ideal time, giving an overview of methods currently applied in the study of non-target effects in biological control of arthropod pests. It provides the first step towards the ultimate goal of devising guidelines for the appropriate methods that should be universally applied for the assessment and minimisation of potential non-target effects. The main topics that are reviewed here include host specificity (including field surveys, selection of non-target test species and testing protocols), post-release studies, competition, overwintering and dispersal. Finally, a number of conclusions that have emerged from this comprehensive compilation of studies are drawn, addressing potential non-target effects in arthropod biological control.

Non-target host acceptance and parasitism by Trichogramma brassicae Bezdenko (Hymenoptera: Trichogrammatidae) in the laboratory

Abstract As part of a risk assessment study, we exposed eggs of 23 non-target lepidopteran species including nine butterflies endangered in Switzerland to individual Trichogramma brassicae Bezdenko females under no-choice conditions in the laboratory. We could show that Papilio machaon L. (Papilionidae), Artogeia (= Pieris ) napi L. (Pieridae), Argynnis adippe Denis & Schiffermuller, Clossiana titania Esper, (Nymphalidae), Aphantopus hyperanthus L., Maniola jurtina L., Coenonympha pamphilus L., Melanargia galathea L., Erebia ligea L., Hipparchia alcyone Denis & Schiffermuller (Satyridae), Polyommatus icarus Rottemburg and Plebejus idas L. (Lycaenidae) were well accepted and not parasitized significantly different (range 73–94%) than the target, Ostinia nubilalis Hubner (81%). Virtually all eggs of Vanessa atalanta L., Argynnis niobe L., Clossiana selene L. (Nymphalidae), and Cyaniris semiargus Rottemburg (Lycaenidae) were accepted for oviposition resulting in significantly higher parasitism rates of 94–97% compared with the target. Melitaea parthenoides Keferstein, M. diamina Lang, and nearly 50% of Mellicta athalia Rottemburg (Nymphalidae) eggs were rejected early in the host selection process. Ovipositional success on eggs of Zygaena filipendula L. (Zygaenidae), Hesperia comma L. (Hesperidae), Sphinx ligustri L., and Deilephila elpenor L. (Sphingidae) was less than 30%. The number of times a female left a host egg before acceptance as well as the time from first host egg contact to acceptance was not related to parasitism rate on the tested non-targets. Offspring emerging from non-target hosts was of similar or even larger size compared to offspring emerging from the target, and in all cases larger compared to individuals emerging from the factitious host, Ephestia kuehniella Zeller. We found that large T. brassicae individuals had significantly higher success in penetrating the chorion and parasitizing eggs of S. ligustri than smaller adults. The results show that T. brassicae parasitizes a number of non-target lepidopteran eggs belonging to different families. Host range and impact under field conditions have yet to be determined.

Potential effects of oilseed rape expressing oryzacystatin-1 (OC-1) and of purified insecticidal proteins on larvae of the solitary bee Osmia bicornis

Despite their importance as pollinators in crops and wild plants, solitary bees have not previously been included in non-target testing of insect-resistant transgenic crop plants. Larvae of many solitary bees feed almost exclusively on pollen and thus could be highly exposed to transgene products expressed in the pollen. The potential effects of pollen from oilseed rape expressing the cysteine protease inhibitor oryzacystatin-1 (OC-1) were investigated on larvae of the solitary bee Osmia bicornis (= O. rufa). Furthermore, recombinant OC-1 (rOC-1), the Bt toxin Cry1Ab and the snowdrop lectin Galanthus nivalis agglutinin (GNA) were evaluated for effects on the life history parameters of this important pollinator. Pollen provisions from transgenic OC-1 oilseed rape did not affect overall development. Similarly, high doses of rOC-1 and Cry1Ab as well as a low dose of GNA failed to cause any significant effects. However, a high dose of GNA (0.1%) in the larval diet resulted in significantly increased development time and reduced efficiency in conversion of pollen food into larval body weight. Our results suggest that OC-1 and Cry1Ab expressing transgenic crops would pose a negligible risk for O. bicornis larvae, whereas GNA expressing plants could cause detrimental effects, but only if bees were exposed to high levels of the protein. The described bioassay with bee brood is not only suitable for early tier non-target tests of transgenic plants, but also has broader applicability to other crop protection products.

Impact of insecticidal proteins expressed in transgenic plants on bumblebee microcolonies

In order to assess the risk that insecticidal transgenic plants may pose for bumblebees, we tested whether Bombus terrestris (L.) (Hymenoptera: Apidae) workers are able to detect insecticidal proteins dissolved in sucrose solution and whether consumption of these proteins will affect survival and offspring production. Feeders containing either Bacillus thuringiensis toxin (Cry1Ab), Kunitz soybean trypsin inhibitor (SBTI), or Galanthus nivalis agglutinin (GNA) were offered to bumblebee colonies at low (0.01% wt/vol for SBTI and GNA, 0.001% for Cry1Ab) and high concentrations (0.1% for SBTI and GNA, 0.01% for Cry1Ab) together with a control (pure sucrose solution) in a glasshouse chamber. No difference was found in the number of visits and the duration of visits among the different concentrations for each of the insecticidal proteins, indicating that bumblebees do not discriminate the compounds. To investigate the impact of the different insecticidal proteins on B. terrestris, microcolonies were established by placing three newly emerged bumblebee workers in wooden boxes. Within a few days, a hierarchy in each microcolony was established and the dominant worker developed its ovaries and laid haploid eggs. Bumblebees were fed with Cry1Ab (0.01%), SBTI, or GNA (both at 0.01 and 0.1%) dissolved in sucrose solution and also fed mixed floral pollen for a maximum period of 80 days. Additionally, microcolonies with three drones each were established to measure individual bee longevity. While the Cry1Ab did not affect microcolony performance, the consumption of SBTI and especially GNA affected survival of B. terrestris workers and drones and caused a significant reduction in the number of offspring. The use of microcolonies appears to be well‐suited to measure lethal and sublethal effects of insecticidal proteins expressed in transgenic plants on bumblebees.

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

We investigated whether mass releases of Trichogramma brassicae against the European corn borer will have detrimental effects on populations of other natural enemies in maize. In a tiered approach, experiments investigated the host acceptance of T. brassicae towards eggs of Chrysoperla carnea, Episyrphus balteatus, Adalia bipunctata, and Coccinella septempunctata under laboratory, caged, and field conditions. The factitious host, Ephestia kuehniella, and in one case also Mamestra brassicae were used as control. Under laboratory conditions, 53% of the T. brassicae females parasitised C. carnea eggs, 70% parasitised E. balteatus eggs, while 91% of the females parasitised E. kuehniella eggs, with T. brassicae emerging from C. carnea, E. balteatus, and E. kuehniella at rates higher than 81%. No parasitoid offspring emerged from eggs of A. bipunctata and C. septempunctata. However, we observed significantly increased mortality on A. bipunctata eggs, compared to the control, and also found young instars of T. brassicae inside A. bipunctata eggs. In a second experiment where the host acceptance behaviour of the parasitoid female was directly observed for 10 min, 10% of T. brassicae females were found to oviposit in eggs of A. bipunctata, but the development of parasitoid offspring failed. No C. septempunctata eggs, 13% of E. balteatus eggs, 23% of C. carnea eggs, 33% of E. kuehniella egg clusters, and 83% of M. brassicae eggs were accepted for oviposition. In the greenhouse under caged conditions, the parasitism rate of C. carnea eggs (7%) and E. balteatus eggs (0.4%) were significantly lower than of E. kuehniella eggs (21 and 27%, respectively). In the final tier, 3.1% of C. carnea eggs were parasitised by T. brassicae under field conditions. This was significantly less than the observed parasitism rate of E. kuehniella egg clusters (64%). From direct observations of the parasitoids’ host acceptance behaviour and the low parasitism rates observed under caged and field conditions, we conclude that detrimental effects of the mass release of T. brassicae on populations of natural enemies in maize are unlikely to occur.

Overwintering of the egg parasitoid Trichogramma brassicae in Northern Switzerland

As part of a general risk assessment study weinvestigated the overwintering abilities ofTrichogramma brassicae Bezd. (Hym.: Trichogrammatidae) in Northern Switzerland. Eggs of six host species parasitized by T. brassicae were exposed under outdoor conditions every two weeksbetween 26 September and 7 November 1998. Wefound that T. brassicae is able tooverwinter successfully on six lepidopteranspecies in the families Tortricidae, Noctuidae,Plutellidae, Pyralidae and Crambidae. Between75 and 100% emergence was observed in thefollowing spring for all of the six tested hostspecies exposed on 26 September. On laterexposure dates, spring emergence decreasedsignificantly and no development of T. brassicae offspring occurred from host eggsparasitized on 7 November.Emergence of T. brassicae from eggs ofEphestia kuehniella Zeller parasitized atweekly intervals in autumn 1999 occurred in thesame year until the end of October if the eggswere parasitized by 10 September. All offspringfrom eggs that were parasitized from 17September onwards went into diapause. Springemergence of T. brassicae adults wasobserved between end of April and beginning ofMay both in 1999 and 2000. Fecundity of T.brassicae females that overwintered on E.kuehniella was not significantly different fromthe fecundity of control females that werereared without diapause under optimalconditions at 25 °C. Our resultsdemonstrate that the egg parasitoid T.brassicae is able to overwinter successfullyin Northern Switzerland and has the potentialto establish in Switzerland. As a result,potential non-target effects are not locallyrestricted but may occur on a largegeographical scale.