Impact of pollen consumption from Cry1Ab- or Cry3Bb1-expressing <i>Bt</i> maize or the corresponding non-transformed varieties on life-table parameters of adult <i>Chrysoperla carnea</i> and results from retrospective power analyses.

<p>Pairs of <i>C. carnea</i> were fed 1 M sucrose solution together with pollen from one of four maize varieties: (a) DKc5143Bt (MON 88017), (b) the corresponding non-transformed control DKc5143, (c) Compa CB (Event Bt176), and (d) the corresponding non-transformed control Dracma. The experiment was terminated after 28 days. No statistical differences (P<0.05) were detected for (a) <i>vs.</i> (b), (c) <i>vs.</i> (d) and (b) <i>vs.</i> (d) for any of the parameters assessed.</p><p>Retrospective power analyses were conducted to calculate the detectable difference as percentage difference of detectable treatment means (a, c) relative to control means (b, d) (α = 0.05, power of 80%).</p>a<p>Experiment started with n = 35 per treatment. Pairs producing no or only infertile eggs removed from analyses; ^bSurvival not analysed since mortality remained below 3% in all treatments. Retrospective power analyses based on log-rank test; ^cMann-Whitney U-test; ^dStudent's t-test.</p

Mean daily fecundity of <i>Chrysoperla carnea</i> fed artificial diet containing insecticidal proteins.

<p>Per g dry weight, 150 µg Cry3Bb1, 120 µg Cry1Ab or 9 mg GNA (positive control) were incorporated. Pure diet served as a negative control. N = 33–35.</p

Impact of feeding purified Cry3Bb1, Cry1Ab and GNA on life-table parameters of adult <i>Chrysoperla carnea</i>.

<p>Pairs of <i>C. carnea</i> were fed an artificial diet containing 150 µg Cry3Bb1, 120 µg Cry1Ab or 9 mg GNA (positive control) per g dry weight of artificial diet. Pure diet served as a negative control. The experiment lasted for 28 days.</p><p>Statistical comparisons were made for each of the insecticidal proteins with the control. Asterisks denote significant differences: ^*<i>P</i><0.05, ^**<i>P</i><0.01; ^aExperiment started with n = 36 per treatment. Pairs producing no or only infertile eggs removed from analyses; ^bChi-square test; ^cMann-Whitney U-test; ^dDunnett test.</p

Acquisition of Cry1Ac Protein by Non-Target Arthropods in <i>Bt</i> Soybean Fields

<div><p>Soybean tissue and arthropods were collected in <i>Bt</i> soybean fields in China at different times during the growing season to investigate the exposure of arthropods to the plant-produced Cry1Ac toxin and the transmission of the toxin within the food web. Samples from 52 arthropod species/taxa belonging to 42 families in 10 orders were analysed for their Cry1Ac content using enzyme-linked immunosorbent assay (ELISA). Among the 22 species/taxa for which three samples were analysed, toxin concentration was highest in the grasshopper <i>Atractomorpha sinensis</i> and represented about 50% of the concentration in soybean leaves. Other species/taxa did not contain detectable toxin or contained a concentration that was between 1 and 10% of that detected in leaves. These Cry1Ac-positive arthropods included a number of mesophyll-feeding Hemiptera, a cicadellid, a curculionid beetle and, among the predators, a thomisid spider and an unidentified predatory bug belonging to the Anthocoridae. Within an arthropod species/taxon, the Cry1Ac content sometimes varied between life stages (nymphs/larvae <i>vs.</i> adults) and sampling dates (before, during, and after flowering). Our study is the first to provide information on Cry1Ac-expression levels in soybean plants and Cry1Ac concentrations in non-target arthropods in Chinese soybean fields. The data will be useful for assessing the risk of non-target arthropod exposure to Cry1Ac in soybean.</p></div

Cry1Ac concentrations in arthropods collected in <i>Bt</i> soybean before, during, and after anthesis in 2010.

<p>ELISA results below the limit of detection (LOD) are indicated as ‘<’with the corresponding LOD value. This table only includes values based on the analysis of three sub-samples.</p>a<p>H– herbivore, P – predator, S – saprophage.</p>b<p>n.c. – not collected.</p

Effect of Substituent on the Mechanism and Chemoselectivity of the Gold(I)-Catalyzed Propargyl Ester Tandem Cyclization

This study reports a detailed theoretical analysis of the mechanisms and chemoselectivity for the formation of benzo­[<i>b</i>]­fluorenes or benzofulvenes from propargyl esters catalyzed by an organometallic Au­(I) complex. Three different substitution patterns within the 1,5-diyne ester substrates were explored to rationalize the reaction mechanism and chemoselectivity. DFT calculations reveal that the title reaction proceeds through four main steps: (i) 1,3-acyl-shift, (ii) 6-<i>endo</i>-<i>dig</i> or 5-<i>exo</i>-<i>dig</i> cyclization, (iii) Friedel–Crafts-type, and (iv) proton transfer, with step (ii) being rate-determining in all studied pathways. In the absence of substituents at the aromatic rings of the substrate (R = H), the 6-<i>endo</i>-<i>dig</i> cyclization is favored. In turn, in the presence of one strong electron-donating substituent at the backbone (R = OCH₃) of the substrate, the 5-<i>exo</i>-<i>dig</i> cyclization is favored. Besides, a modification of the substrate’s acetyl group by a pivaloyl group leads to an activation barrier difference between the 6-<i>endo</i>-<i>dig</i> and 5-<i>exo</i>-<i>dig</i> cyclizations, which increases and suppresses the formation of benzofulvenes. The obtained theoretical data are in a very good agreement with prior experimental evidence, suggesting that the substituent plays a crucial role in the outcome of the final product. High chemoselectivity can be explained by the hindrance (torsional strain) along the forming C–C bond and the carbocation stability provided by substituents

Detection of Cry1Ac in arthropods collected from <i>Bt</i> soybean plots at different growth stages for which only one or two sub-samples were analysed (by ELISA).

a<p>A: adults, L: larvae, M: mixture of all available stages, N: nymphs; n.i. = species not identified.</p

Cry1Ac toxin concentrations (µg/g dry weight, mean+SE) in plant tissues of <i>Bt</i> soybean from the field.

<p>Samples were taken before (I), during (II) and after anthesis (III) (n = 6). Bars with different letters are significantly different at <i>P</i><0.05.</p

Concentrations (mean+SD) of Cry1Ac and Cry2Ab in larvae of <i>Trichoplusia ni</i> and <i>Coleomegilla maculata</i> (FW = fresh weight).

<p>2nd instar larvae of <i>Trichoplusia ni</i> fed on BollGard II® cotton for 3 days, and the 2nd instar larvae of <i>Coleomegilla maculata</i> had fed <i>Bt</i>-cotton reared <i>T. ni</i> larvae for 3 days (based on fresh weigh). The asterisks “**” indicate the level of significance (P<0.01) in the Cry protein (Cry2Ab or Cry1Ac) concentrations between <i>T. ni</i> and <i>C. maculata</i>. (N = 5).</p

Impact of purified Cry1Ac, Cry2Ab and E-64 provided in artificial diet on survival and development of <i>Coleomegilla maculata</i>.

<p>Larvae of <i>C. maculata</i> were fed an artificial diet containing 100 µg Cry1Ac, 400 µg Cry2Ab, 100 µg Cry1Ac and 400 µg Cry2Ab, or 150 µg E-64 (positive control) per g fresh weight of artificial diet. Pure diet served as a negative control (N = 30). The experiment lasted until adult emergence.</p><p>Statistical comparisons were made separately for each of the insecticidal proteins with the control. Asterisks denote significant differences:</p><p>**<i>P</i><0.01.</p><p>*Chi-square test with Bonferroni correction (adjusted α = 0.017).</p><p>†Mann-Whitney U-test with Bonferroni correction (adjusted α = 0.017).</p><p>‡Dunnett test.</p