Successful pest management in multi-crop systems should be based on sound ecological knowledge about the pest and the plant system. Such knowledge is critical to achieve sustainable pest management against cosmopolitan pests such as the sweetpotato whitefly, Bemisia tabaci. From 2000 to 2003 we conducted an experiment aimed at determining the factors that govern and limit the year-round development of unmanaged (unsprayed) B. tabaci populations in Arizona. Population dynamic data showed that B. tabaci survives the winter in broccoli and various weeds, colonizing cantaloupe, lantana, and some weeds during the spring and mid-summer, finally reaching outbreak levels during late summer and fall. Cohort-based life tables were used to identify causes and estimate rates of immature whitefly mortality in six host plants. Survival in most crops ranged between 0 and 30% with the exception of spring cantaloupe where survival ranged between 12 and 56%. Predation by sucking predators and dislodgment (missing) were major sources of egg and nymphal mortality. Parasitism by aphelinid wasps was generally low all years, but contributed to natural enemy induced mortality in cotton, lantana, and alfalfa. Most mortality occurred during the egg stage and fourth nymphal stadium. Key-factor analyses identified predation, dislodgement and various forces affecting fourth instar nymphs as the best predictors of total generational mortality. In summary, the combination of all these factors contribute to high levels of mortality in unmanaged populations of B. tabaci. This understanding is aiding on-going efforts to develop ecologically based management strategies in all affected cropping systems.
Species 1: Homoptera Aleyrodidae Bemisia tabaci (silverleaf whitefly, sweetpotato whitefly)
Species 2: Homoptera Aleyrodidae Bemisia argentifolii (silverleaf whitefly, sweetpotato whitefly)
Keywords: life table, mortality
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