Season-long expression of Cry1Ac and Cry2Ab proteins in Bollgard II cotton in Australia

Knight, Kristen; Head, Graham P.; Rogers, John

doi:10.1016/j.cropro.2012.10.014

Cited by 27 publications

(22 citation statements)

References 19 publications

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“…() and Knight et al . () provide ELISA data for field‐grown Bollgard II cotton. Concentrations of Cry1Ac and Cry2Ab were 3–4 times higher than the values measured in our study.…”

Section: Discussionmentioning

confidence: 99%

“…The Cry1Ac and Cry2Ab values measured in Bt cotton leaf material in our study were rather low compared to the values available in the literature. Greenplate et al (2003) and Knight et al (2013) provide ELISA data for field-grown Bollgard II cotton. Concentrations of Cry1Ac and Cry2Ab were 3-4 times higher than the values measured in our study.…”

Section: Bt Protein In Plant Tissuementioning

confidence: 99%

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Transfer of Cry1Ac and Cry2Ab proteins from genetically engineered Bt cotton to herbivores and predators

Meissle

Romeis

2017

Insect Science

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With the cultivation of Bt cotton, the produced insecticidal Cry proteins are ingested by herbivores and potentially transferred along the food chain to natural enemies, such as predators. In laboratory experiments with Bollgard II cotton, concentrations of Cry1Ac and Cry2Ab were measured in Lepidoptera larvae (Spodoptera littoralis, Heliothis virescens), plant bugs (Euschistus heros), aphids (Aphis gossypii), whiteflies (Bemisia tabaci), thrips (Thrips tabaci, Frankliniella occidentalis), and spider mites (Tetranychus urticae). Tritrophic experiments were conducted with caterpillars of S. littoralis as prey and larvae of ladybird beetles (Harmonia axyridis, Adalia bipunctata) and lacewings (Chrysoperla carnea) as predators. Immunological measurements (ELISA) indicated that herbivores feeding on Bt cotton contained 5%–50% of the Bt protein concentrations in leaves except whiteflies and aphids, which contained no or only traces of Bt protein, and spider mites, which contained 7 times more Cry1Ac than leaves. Similarly, predators contained 1%–30% of the Cry protein concentration in prey. For the nontarget risk assessment, this indicates that Bt protein concentrations decrease considerably from one trophic level to the next in the food web, except for spider mites that contain Bt protein concentrations higher than those measured in the leaves. Exposure of phloem sucking hemipterans is negligible.

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“…() and Knight et al . () provide ELISA data for field‐grown Bollgard II cotton. Concentrations of Cry1Ac and Cry2Ab were 3–4 times higher than the values measured in our study.…”

Section: Discussionmentioning

confidence: 99%

Section: Bt Protein In Plant Tissuementioning

confidence: 99%

Transfer of Cry1Ac and Cry2Ab proteins from genetically engineered Bt cotton to herbivores and predators

Meissle

Romeis

2017

Insect Science

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“…Four cotton cultivars were planted in the field on April 17, 2014, at Luhe in the Jiangsu province of China. Cultivars were GK19 producing the fusion protein Cry1Ac/Cry1Ab, its non‐Bt cotton parent cultivar Simian3 (Wan, Zhang, Wu, & Huang, ), 33B producing Cry1Ac toxin (Bollgard), and a dual Bt cotton variety (Bollgard 2) producing Cry1Ac toxin and Cry2Ab protoxin (Knight, Head, & Rogers, ). No insecticides were used to protect cotton plants.…”

Section: Methodsmentioning

confidence: 99%

Resistance to Bacillus thuringiensis toxin Cry2Ab and survival on single‐toxin and pyramided cotton in cotton bollworm from China

Liu

Gao

Song

et al. 2016

Evolutionary Applications

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Evolution of Helicoverpa armigera resistance to Bacillus thuringiensis (Bt) cotton producing Cry1Ac is progressing in northern China, and replacement of Cry1Ac cotton by pyramided Bt cotton has been considered to counter such resistance. Here, we investigated four of the eight conditions underlying success of the refuge strategy for delaying resistance to Cry1Ac+Cry2Ab cotton, a pyramid that has been used extensively against H. armigera outside China. Laboratory bioassays of a Cry2Ab-selected strain (An2Ab) and a related unselected strain (An) reveal that resistance to Cry2Ab (130-fold) was nearly dominant, autosomally inherited, and controlled by more than one locus. Strong cross-resistance occurred between Cry2Ab and Cry2Aa (81-fold).Weaker cross-resistance (18-to 22-fold) between Cry2Ab and Cry1A toxins was also present and significantly increased survival of An2Ab relative to An on cotton cultivars producing the fusion protein Cry1Ac/Cry1Ab or Cry1Ac. Survival on Cry1Ac+Cry2Ab cotton was also significantly higher in An2Ab than in An, showing that redundant killing on this pyramid was incomplete. Survival on non-Bt cotton did not differ significantly between An2Ab and An, indicating an absence of fitness costs affecting this trait. These results indicate that a switch to three-toxin pyramided cotton could be valuable for increasing durability of Bt cotton in China. K E Y W O R D S

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“…). In several other studies, H. armigera larvae from Australia appeared to avoid toxins by selecting a plant part low in Bt or a diet not treated with Cry1Ac and Cry2Ab endotoxins (Lu et al ; Knight et al ). On conventional cotton plants, although H. armigera first‐instar larvae trended to feed on young leaves and small squares if available, they were less likely to be found on young Bt leaves (the more toxic plant parts in terms of Bt toxin; Yang et al ).…”

Section: Introductionmentioning

confidence: 99%

“…Knight et al . () indicated that more movement by larvae on Bt cotton plants could provide a greater chance for Helicoverpa spp. to encounter better food resources such as flowers.…”

Section: Introductionmentioning

confidence: 99%

Feeding behaviour and survival of Bacillus thuringiensis‐resistant and Bacillus thuringiensis‐susceptible larvae of Helicoverpa armigera (Lepidoptera: Noctuidae) exposed to a diet with Bacillus thuringiensis toxin

et al. 2017

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Although higher than expected numbers of surviving larvae of Helicoverpa spp. are reported in some Bollgard II cotton fields from time to time, there is no convincing evidence that field resistance has developed. A behavioural component, specifically the avoidance of the toxin, was considered to contribute to larvae surviving on Bacillus thuringiensis (Bt) toxin-expressing plants. Experiments were conducted with Bt-susceptible and Bt-resistant larvae of Helicoverpa armigera to investigate (1) how larval responses to food deprivation might lead to differences in survival and therefore how far neonates could move to find a suitable feeding site and (2) whether larvae that are physiologically susceptible vs. resistant behave differently when feeding on diet with Bt and without Bt toxins. Bt-susceptible neonates of H. armigera, which were significantly heavier, could survive without food for longer and recover better than Bt-resistant neonates. Although H. armigera neonates did not shift their behaviour with respect to Bt toxin on artificial diet before their first feeding event, the tendency of Bt-susceptible larvae to remain on non-Bt diet and move off Bt diet may allow them to survive in a Bt environment. This behaviour resulted in a higher percentage of survival in situations where a diet choice was offered.

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Season-long expression of Cry1Ac and Cry2Ab proteins in Bollgard II cotton in Australia

Cited by 27 publications

References 19 publications

Transfer of Cry1Ac and Cry2Ab proteins from genetically engineered Bt cotton to herbivores and predators

Transfer of Cry1Ac and Cry2Ab proteins from genetically engineered Bt cotton to herbivores and predators

Resistance to Bacillus thuringiensis toxin Cry2Ab and survival on single‐toxin and pyramided cotton in cotton bollworm from China

Feeding behaviour and survival of Bacillus thuringiensis‐resistant and Bacillus thuringiensis‐susceptible larvae of Helicoverpa armigera (Lepidoptera: Noctuidae) exposed to a diet with Bacillus thuringiensis toxin

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