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Title: LIFE TABLE ANALYSIS OF BEMISIA TABACI IN COTTON

Author
item Naranjo, Steven
item ELLSWORTH, PETER - U OF AZ, MARICOPA, AZ

Submitted to: Sweetpotato Whitefly Progress Review Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: 5/1/2000
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: Many mortality factors impact the population dynamics of Bemisia tabaci in agricultural ecosystems, yet we have a poor understanding of the rates of these mortality factors and how they may be involved in overall population regulation. To begin to unravel this complex problem we used a direct observation technique to construct cohort-based life tables of B. tabaci on ncotton in central Arizona. These studies have identified, quantified, and compared in situ sources and rates of mortality of immature whitefly stages in unsprayed cotton fields and fields subject to different insecticide- based management regimes. A total 14 life tables have been completed in unmanaged cotton from 1997-1999. Survival from egg to adulthood ranged from 0-27% and was lt 10% in the majority of generations. Predation and dislodgment were major sources of egg and nymphal mortality in most generations. Egg inviability was high during a few generations and an unexplained factor caused high rates of nymphal mortality during 2 generations in 1998 and 1999. Parasitism was consistently low all years. Key-factor analyses identified egg inviability and various forces affecting 4th instar nymphs as the best predictors of total generational mortality. Preliminary analyses suggest that most mortality forces act in a density- independent manner. Further analyses showed that various mortality factors interact and readily replace one another during the 5 developmental stages.