Annals of Applied Biology (2014) 165, 108-116

S.M. Prager, X. Martini, H. Guvvala, C. Nansen and J. Lundgren (2014)
Spider mite infestations reduce Bacillus thuringiensis toxin concentration in corn leaves and predators avoid spider mites that have fed on Bacillus thuringiensis corn
Annals of Applied Biology 165 (1), 108-116
Abstract: Perceived benefits of insecticidal transgenic crops include reduced usage of broad-based insecticides, and therefore lower risk to non-target organisms. Numerous studies have documented low or no direct toxicity of Bacillus thuringiensis (Bt)-derived toxins against non-target organisms, but there has been less research on (a) effects of secondary pest infestations on Bt expressing in crops and (b) behavioural responses by predators feeding on host arthropods from Bt crops - both topics are investigated in this study. We quantified predation by the obligate spider mite predator Phytoseiulus persimilis of carmine spider mites (Tetranychus cinnabarinus), reared on Bt or non-Bt corn (Zea mays). Both no-choice and two-choice studies were conducted. In addition, we quantified toxin levels in corn leaves with/without spider mite infestation. Under no-choice conditions, P. persimilis consumed non-Bt spider mites at a faster rate than Bt spider mites. Under two-choice conditions, P. persimilis spent more time in the vicinity of non-Bt spider mites than near Bt spider mites. Corn infested with spider mites exhibited lower toxin levels than non-infested plants. These results suggest potentially complex interactions among non-target herbivores, their natural enemies and Bt crops.
(The abstract is excluded from the Creative Commons licence and has been copied with permission by the publisher.)
Link to article at publishers website
Database assignments for author(s): Xavier Martini, Sean M. Prager, Jonathan G. Lundgren, Christian Nansen

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

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Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Tetranychus cinnabarinus	Maize/corn (Zea mays)
Phytoseiulus persimilis (predator)	Tetranychus cinnabarinus	Maize/corn (Zea mays)
Bacillus thuringiensis genes in crops (entomopathogen)