PLoS ONE (2012) 7 (9 - e44867)

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Carla C. Dutra, Robert L. Koch, Eric C. Burkness, Michael Meissle, Joerg Romeis, William D. Hutchison and Marcos G. Fernandes (2012)
Harmonia axyridis (Coleoptera: Coccinellidae) exhibits no preference between Bt and non-Bt maize fed Spodoptera frugiperda (Lepidoptera: Noctuidae)
PLoS ONE 7 (9 - e44867)
Abstract: A recent shift in managing insect resistance to genetically engineered (GE) maize consists of mixing non-GE seed with GE seed known as "refuge in a bag", which increases the likelihood of predators encountering both prey fed Bt and prey fed non-Bt maize. We therefore conducted laboratory choice-test feeding studies to determine if a predator, Harmonia axyridis, shows any preference between prey fed Bt and non-Bt maize leaves. The prey species was Spodoptera frugiperda, which were fed Bt maize (MON-810), expressing the single Cry1Ab protein, or non-Bt maize. The predators were third instar larvae and female adults of H. axyridis. Individual predators were offered Bt and non-Bt fed prey larvae that had fed for 24, 48 or 72 h. Ten and 15 larvae of each prey type were offered to third instar and adult predators, respectively. Observations of arenas were conducted at 1, 2, 3, 6, 15 and 24 h after the start of the experiment to determine the number and type of prey eaten by each individual predator. Prey larvae that fed on non-Bt leaves were significantly larger than larvae fed Bt leaves. Both predator stages had eaten nearly all the prey by the end of the experiment. However, in all combinations of predator stage and prey age, the number of each prey type consumed did not differ significantly. ELISA measurements confirmed the presence of Cry1Ab in leaf tissue (23–33 µg/g dry weight) and S. frugiperda (2.1–2.2 µg/g), while mean concentrations in H. axyridis were very low (0.01–0.2 µg/g). These results confirm the predatory status of H. axyridis on S. frugiperda and that both H. axyridis adults and larvae show no preference between prey types. The lack of preference between Bt-fed and non-Bt-fed prey should act in favor of insect resistance management strategies using mixtures of GE and non-GE maize seed.
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Full text of article
Database assignments for author(s): Robert L. Koch, Eric C. Burkness, William (Bill) D. Hutchison, Jörg Romeis, Michael Meissle

Research topic(s) for pests/diseases/weeds:
biocontrol - natural enemies
Research topic(s) for beneficials or antagonists:
environment/habitat manipulation

Pest and/or beneficial records:

Beneficial Pest/Disease/Weed Crop/Product Country Quarant.

Spodoptera frugiperda Maize/corn (Zea mays)
Harmonia axyridis (predator) Spodoptera frugiperda Maize/corn (Zea mays)
Bacillus thuringiensis genes in crops (entomopathogen) Spodoptera frugiperda Maize/corn (Zea mays)
Bacillus thuringiensis Cry1A-toxin (entomopathogen) Spodoptera frugiperda Maize/corn (Zea mays)