Journal of Economic Entomology (2013) 106, 1260-1273

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Peter Asiimwe, Steven E. Naranjo and Peter C. Ellsworth (2013)
Relative influence of plant quality and natural enemies on the seasonal dynamics of Bemisia tabaci (Hemiptera: Aleyrodidae) in cotton
Journal of Economic Entomology 106 (3), 1260-1273
Abstract: The abundance and distribution of insect herbivores is determined by, among other things, plant quality and natural enemies. These two factors vary temporally and spatially, subsequently affecting seasonal population dynamics. The relative influence of plant quality and natural enemies on the seasonal dynamics of Bemisia tabaci (Gennadius) was investigated in a 3-yr field study in cotton. Plant quality was manipulated through varying irrigation regimes: irrigations done at 20, 40, and 60% soil water depletions; and natural enemy densities were manipulated using broad spectrum insecticide applications that reduced their densities compared with unsprayed controls. In each year, densities of B. tabaci eggs, large nymphs and adults were consistently higher when natural enemy densities were reduced compared with when they were left unaltered, regardless of irrigation regime. In contrast, effects of plant quality on densities of all whitefly stages were weak and inconsistent. In addition, natural enemy densities and predator:prey ratios also were not generally affected by plant quality. Interactions between natural enemies and plant quality on whitefly dynamics were rare. In general, whitefly densities were elevated two-thirds of the time and increased two- to sixfold when natural enemy densities were reduced compared with plant quality effects which influenced whitefly densities about one-third of the time and were expressed inconsistently over the years. This indicates that natural enemies exert a comparatively greater influence on seasonal dynamics of B. tabaci in cotton than plant quality, as manipulated by differential irrigation.
(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): Peter C. Ellsworth, Steven E. Naranjo

Research topic(s) for pests/diseases/weeds:
population dynamics/ epidemiology
environment - cropping system/rotation
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 Cotton (Gossypium) U.S.A. (SW)
Geocoris punctipes (predator) Bemisia tabaci Cotton (Gossypium) U.S.A. (SW)
Orius tristicolor (predator) Bemisia tabaci Cotton (Gossypium) U.S.A. (SW)
Geocoris pallens (predator) Bemisia tabaci Cotton (Gossypium) U.S.A. (SW)
Zelus renardii (predator) Bemisia tabaci Cotton (Gossypium) U.S.A. (SW)
Mecaphesa celer (predator) Bemisia tabaci Cotton (Gossypium) U.S.A. (SW)