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

Setting the record straight: a rebuttal to an erroneous analysis on transgenic insecticidal crops and natural enemies

While we think that environmental risk assessments of transgenic insect-resistant crops are important, we believe the paper by Lövei et al. (2009) advocates inappropriate summarization and statistical methods, a negatively biased and incorrect interpretation of the published data on non-target effects, and fails to place any putative effect into a meaningful ecological context. Such erroneous analyses do not serve the scientific or regulatory communities

Recommendations for the design of laboratory studies on non-target arthropods for risk assessment of genetically engineered plants

This paper provides recommendations on experimental design for early-tier laboratory studies used in risk assessments to evaluate potential adverse impacts of arthropod-resistant genetically engineered (GE) plants on non-target arthropods (NTAs). While we rely heavily on the currently used proteins from Bacillus thuringiensis (Bt) in this discussion, the concepts apply to other arthropod-active proteins. A risk may exist if the newly acquired trait of the GE plant has adverse effects on NTAs when they are exposed to the arthropod-active protein. Typically, the risk assessment follows a tiered approach that starts with laboratory studies under worst-case exposure conditions; such studies have a high ability to detect adverse effects on non-target species. Clear guidance on how such data are produced in laboratory studies assists the product developers and risk assessors. The studies should be reproducible and test clearly defined risk hypotheses. These properties contribute to the robustness of, and confidence in, environmental risk assessments for GE plants. Data from NTA studies, collected during the analysis phase of an environmental risk assessment, are critical to the outcome of the assessment and ultimately the decision taken by regulatory authorities on the release of a GE plant. Confidence in the results of early-tier laboratory studies is a precondition for the acceptance of data across regulatory jurisdictions and should encourage agencies to share useful information and thus avoid redundant testing

Novel resistance mechanisms of a wild tomato against the glasshouse whitefly

International audienceAbstractThe glasshouse whitefly, Trialeurodes vaporariorum, is an important pest of many crop plants including tomato, Solanum lycopersicum. Many wild tomato species exhibit a higher resistance to whiteflies. Therefore, locating the source of this enhanced resistance and breeding it into commercial tomato species is an important strategy to reduce the impact of pests on crops. Here, we assessed the pest resistance of Lycopersicon pimpinellifolium by comparing oviposition and feeding data from T. vaporariorum on this wild tomato species with data collected from a susceptible commercial tomato, S. lycopersicum var. ‘Elegance’. The location of resistance factors was examined by use of electrical penetration graph (EPG) studies on these tomato species. Results show that whiteflies preferentially settled on the commercial tomato more often in 80 % of the replicates when given free choice between the two tomato species and laid significantly fewer eggs on L. pimpinellifolium. Whiteflies exhibited a shorter duration of the second feeding bout, reduced pathway phase probing, longer salivation in the phloem and more non-probing activities in the early stages of the EPG on the wild tomato species compared to the commercial tomato. These findings evidence that a dual mode of resistance is present in this wild tomato against T. vaporariorum: a post-penetration, pre-phloem resistance mechanism and a phloem-located factor, which to the best of our knowledge is the first time that evidence for this has been presented. These findings can be used to inform future breeding strategies to increase the resistance of commercial tomato varieties against this important pest

Direct effects of snowdrop lectin (GNA) on larvae of three aphid predators and fate of GNA after ingestion.

Plants genetically modified to express Galanthus nivalis agglutinin (GNA) have been found to confer partial resistance to homopteran pests. Laboratory experiments were conducted to investigate direct effects of GNA on larvae of three species of aphid predators that differ in their feeding and digestive physiology, i.e. Chrysoperla carnea, Adalia bipunctata and Coccinella septempunctata. Longevity of all three predator species was directly affected by GNA, when they were fed a sucrose solution containing 1% GNA. However, a difference in sensitivity towards GNA was observed when comparing the first and last larval stage of the three species. In vitro studies revealed that gut enzymes from none of the three species were able to break down GNA. In vivo feed-chase studies demonstrated accumulation of GNA in the larvae. After the larvae had been transferred to a diet devoid of GNA, the protein stayed present in the body of C. carnea, but decreased over time in both ladybirds. Binding studies showed that GNA binds to glycoproteins that can be found in the guts of larvae of all three predator species. Immunoassay by Western blotting of haemolymph samples only occasionally showed the presence of GNA. Fluorescence microscopy confirmed GNA accumulation in the midgut of C. carnea larvae. Implications of these findings for non-target risk assessment of GNA-transgenic crops are discussed

Experimental treatments of feeding assay with <i>Osmia bicornis</i> larvae.

<p>Larval pollen provisions were collected and processed by nesting bees. Provisions containing non-transgenic pollen from the isoline were manually ‘spiked’ with insecticidal protein dissolved in water to achieve the test concentrations indicated (w∶w). aPercentage OC-1 of total soluble protein in pollen extract, determined by dot-blot immunoassay. Abbreviations: OC-1, oryzacystatin-1; rOC-1, recombinant OC-1; GNA, <i>Galanthus nivalis</i> agglutinin.</p

Stability of insecticidal proteins over time when added to pollen provisions.

<p>Amount of insecticidal protein determined by ELISA after 14 and 28 days of incubation presented as percentage of the amount detected immediately after protein application. Minimum and maximum values of independent determinations and the sample means (in brackets) are given (n = 3–9). Abbreviations: rOC-1, recombinant oryzacystatin-1; GNA, <i>Galanthus nivalis</i> agglutinin.</p

Bee mortality.

<p>Mortality of <i>Osmia bicornis</i> (in %) observed during development (i.e. from hatching to mature larva), in the cocoon (i.e. from start of cocoon spinning to emergence from cocoon) and over the whole observation time (n = 25–44). The 95% confidence interval is given in brackets. Abbreviations: OC-1, oryzacystatin-1; rOC-1, recombinant OC-1; GNA, <i>Galanthus nivalis</i> agglutinin.</p