Ecological Entomology (2016) 41, 642-652

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Peter Asiimwe, Peter C. Ellsworth and Steven E. Naranjo (2016)
Natural enemy impacts on Bemisia tabaci (MEAM1) dominate plant quality effects in the cotton system
Ecological Entomology 41 (5), 642-652
Abstract: 1. Plant quality (bottom-up effects) and natural enemies (top-down effects) affect herbivore performance. Furthermore, plant quality can also influence the impact of natural enemies.
2. Lower plant quality through reduced irrigation increased the abundance of the cryptic species from the Bemisia tabaci complex [hereafter B. tabaci Middle East Asia Minor 1 (MEAM1)], but not its natural enemies on cotton. It was therefore predicted that lower plant quality would diminish the impact of natural enemies in regulating this herbivore.
3. Over three cotton seasons, plant quality was manipulated via differential irrigation and natural enemy abundance with insecticides. Life tables were used to evaluate the impact of these factors on mortality of immature B. tabaci (MEAM1) over nine generations.
4. Mortality of B. tabaci (MEAM1) was consistently affected by natural enemies but not by plant quality. This pattern was driven by high levels of sucking predation, which was the primary (key) factor associated with changes in immature mortality across all irrigation and natural enemy treatments. Dislodgement (chewing predation and weather) and parasitism contributed as key factors in some cases. Analyses also showed that elimination of sucking predation and dislodgement would have the greatest effect on overall mortality.
5. The top-down effects of natural enemies had dominant effects on populations of B. tabaci (MEAM1) relative to the bottom-up effects of plant quality. Effects were primarily due to native generalist arthropod predators and not more host-specific aphelinid parasitoids. The findings of this study demonstrate the important role of arthropod predators in population suppression and validate the importance of conservation biological control in this system for effective pest control.
(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): Steven E. Naranjo, Peter C. Ellsworth

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.

Bemisia tabaci biotype MEAM1 Cotton (Gossypium)