Journal of Entomological Science (1997) 32, 445-459

B.C. Legaspi, J.C. Legaspi, R.I. Carruthers, J. Goolsby, J. Hadman, W. Jones, D. Murden and L. Wendel (1997)
Areawide population dynamics of silverleaf whitefly (Homoptera, Aleyrodidae) and its parasitoids in the lower Rio Grande valley of Texas
Journal of Entomological Science 32 (4), 445-459
Abstract: The population dynamics of the silverleaf whitefly (SLWF), Bemisia argentifolii Bellows and Perring (=sweetpotato whitefly, B. tabaci Biotype "B", [Gennadius]), and its endemic parasitoids (mostly Encarsia spp. [Aphelinidae]) were monitored in a heterogeneous cropping area, consisting of cotton, cantaloupe and kenaf (tall fiber crop). To assess the suitability of the whitefly for areawide pest management, we compared estimates of population densities using different sampling methods and determined the effects of agronomic practices on the whitefly and parasitoid populations. There was no correlation between adult SLWF estimates using sticky traps and those counted directly on the leaves. However, counts of immatures using disk subsamples were found to be good predictors of whole leaf counts. SLWF counts were low in cotton, until the harvest period of cantaloupes, which may have triggered migration from cantaloupe to cotton. The determinants of emigration from cotton were less clear. High numbers of adults were migrating well before harvest or the application of a defoliant. One likely contributing factor in triggering whitefly migration was leaf senescence. Despite rather high adult densities sampled in kenaf, populations of immature SLWF were low, suggesting that it is not a preferred host. Parasitoid populations were high in the kenaf fields, causing 20 to 80% parasitism and suggesting that kenaf could serve as a reservoir of natural enemies within a larger cropping system. Parasitism in cotton was less than that in kenaf, usually at ~10 to 15%. Encarsia spp. sampled on sticky traps indicated significant activity of the adults in the cotton and kenaf fields, and much lower numbers in the cantaloupe. Because it is a dispersive and polyphagous pest, areawide suppression of SLWF must include the consequences of farming practices and cropping patterns in heterogeneous fields, especially when they are under different management.
(The abstract is excluded from the Creative Commons licence and has been copied with permission by the publisher.)
Database assignments for author(s): Jesusa Crisostomo Legaspi

Research topic(s) for pests/diseases/weeds:
population dynamics/ epidemiology
biocontrol - natural enemies
Research topic(s) for beneficials or antagonists:
population dynamics/epizootiology

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Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Bemisia tabaci biotype MEAM1		U.S.A. (mid S)